Merge pull request #972 from tendermint/feature/enhance-endblock

Update EndBlock parameters
2026-06-03 12:56:22 +00:00 · 2017-12-22 01:30:58 -05:00
parent a3c7525249 38608b1b0f
commit c2436c46e6
33 changed files with 750 additions and 302 deletions
--- a/blockchain/reactor.go
+++ b/blockchain/reactor.go
@@ -183,7 +183,7 @@ func (bcR *BlockchainReactor) Receive(chID byte, src p2p.Peer, msgBytes []byte)
 // maxMsgSize returns the maximum allowable size of a
 // message on the blockchain reactor.
 func (bcR *BlockchainReactor) maxMsgSize() int {
-	return bcR.state.Params.BlockSizeParams.MaxBytes + 2
+	return bcR.state.ConsensusParams.BlockSize.MaxBytes + 2
 }

 // Handle messages from the poolReactor telling the reactor what to do.
@@ -251,7 +251,7 @@ FOR_LOOP:
 					// We need both to sync the first block.
 					break SYNC_LOOP
 				}
-				firstParts := first.MakePartSet(bcR.state.Params.BlockPartSizeBytes)
+				firstParts := first.MakePartSet(bcR.state.ConsensusParams.BlockPartSizeBytes)
 				firstPartsHeader := firstParts.Header()
 				// Finally, verify the first block using the second's commit
 				// NOTE: we can probably make this more efficient, but note that calling
--- a/blockchain/reactor_test.go
+++ b/blockchain/reactor_test.go
@@ -41,7 +41,7 @@ func newBlockchainReactor(logger log.Logger, maxBlockHeight int64) *BlockchainRe
 	for blockHeight := int64(1); blockHeight <= maxBlockHeight; blockHeight++ {
 		firstBlock := makeBlock(blockHeight, state)
 		secondBlock := makeBlock(blockHeight+1, state)
-		firstParts := firstBlock.MakePartSet(state.Params.BlockGossipParams.BlockPartSizeBytes)
+		firstParts := firstBlock.MakePartSet(state.ConsensusParams.BlockGossip.BlockPartSizeBytes)
 		blockStore.SaveBlock(firstBlock, firstParts, secondBlock.LastCommit)
 	}

@@ -105,14 +105,7 @@ func makeTxs(height int64) (txs []types.Tx) {
 }

 func makeBlock(height int64, state *sm.State) *types.Block {
-	prevHash := state.LastBlockID.Hash
-	prevParts := types.PartSetHeader{}
-	valHash := state.Validators.Hash()
-	prevBlockID := types.BlockID{prevHash, prevParts}
-	block, _ := types.MakeBlock(height, "test_chain", makeTxs(height),
-		state.LastBlockTotalTx, new(types.Commit),
-		prevBlockID, valHash, state.AppHash,
-		state.Params.BlockGossipParams.BlockPartSizeBytes)
+	block, _ := state.MakeBlock(height, makeTxs(height), new(types.Commit))
 	return block
 }

--- a/circle.yml
+++ b/circle.yml
@@ -25,7 +25,6 @@ dependencies:

 test:
  override:
-    - cd "$PROJECT_PATH" && make tools && make get_vendor_deps && make metalinter_test
    - cd "$PROJECT_PATH" && set -o pipefail && make test_integrations 2>&1 | tee test_integrations.log:
        timeout: 1800
  post:
--- a/consensus/replay_test.go
+++ b/consensus/replay_test.go
@@ -107,9 +107,9 @@ func TestWALCrash(t *testing.T) {
 		{"block with a smaller part size",
 			func(cs *ConsensusState, ctx context.Context) {
 				// XXX: is there a better way to change BlockPartSizeBytes?
-				params := cs.state.Params
+				params := cs.state.ConsensusParams
 				params.BlockPartSizeBytes = 512
-				cs.state.Params = params
+				cs.state.ConsensusParams = params
 				sendTxs(cs, ctx)
 			},
 			1},
@@ -392,7 +392,7 @@ func testHandshakeReplay(t *testing.T, nBlocks int, mode uint) {
 }

 func applyBlock(st *sm.State, blk *types.Block, proxyApp proxy.AppConns) {
-	testPartSize := st.Params.BlockPartSizeBytes
+	testPartSize := st.ConsensusParams.BlockPartSizeBytes
 	err := st.ApplyBlock(types.NopEventBus{}, proxyApp.Consensus(), blk, blk.MakePartSet(testPartSize).Header(), mempool)
 	if err != nil {
 		panic(err)
@@ -590,7 +590,7 @@ func stateAndStore(config *cfg.Config, pubKey crypto.PubKey) (*sm.State, *mockBl
 	state, _ := sm.MakeGenesisStateFromFile(stateDB, config.GenesisFile())
 	state.SetLogger(log.TestingLogger().With("module", "state"))

-	store := NewMockBlockStore(config, state.Params)
+	store := NewMockBlockStore(config, state.ConsensusParams)
 	return state, store
 }

--- a/consensus/state.go
+++ b/consensus/state.go
@@ -863,10 +863,7 @@ func (cs *ConsensusState) createProposalBlock() (block *types.Block, blockParts

 	// Mempool validated transactions
 	txs := cs.mempool.Reap(cs.config.MaxBlockSizeTxs)
-	return types.MakeBlock(cs.Height, cs.state.ChainID, txs,
-		cs.state.LastBlockTotalTx, commit,
-		cs.state.LastBlockID, cs.state.Validators.Hash(),
-		cs.state.AppHash, cs.state.Params.BlockPartSizeBytes)
+	return cs.state.MakeBlock(cs.Height, txs, commit)
 }

 // Enter: `timeoutPropose` after entering Propose.
@@ -1306,7 +1303,7 @@ func (cs *ConsensusState) addProposalBlockPart(height int64, part *types.Part, v
 		var n int
 		var err error
 		cs.ProposalBlock = wire.ReadBinary(&types.Block{}, cs.ProposalBlockParts.GetReader(),
-			cs.state.Params.BlockSizeParams.MaxBytes, &n, &err).(*types.Block)
+			cs.state.ConsensusParams.BlockSize.MaxBytes, &n, &err).(*types.Block)
 		// NOTE: it's possible to receive complete proposal blocks for future rounds without having the proposal
 		cs.Logger.Info("Received complete proposal block", "height", cs.ProposalBlock.Height, "hash", cs.ProposalBlock.Hash())
 		if cs.Step == cstypes.RoundStepPropose && cs.isProposalComplete() {
@@ -1341,7 +1338,8 @@ func (cs *ConsensusState) tryAddVote(vote *types.Vote, peerKey string) error {

 			return err
 		} else {
-			// Probably an invalid signature. Bad peer.
+			// Probably an invalid signature / Bad peer.
+			// Seems this can also err sometimes with "Unexpected step" - perhaps not from a bad peer ?
 			cs.Logger.Error("Error attempting to add vote", "err", err)
 			return ErrAddingVote
 		}
--- a/consensus/state_test.go
+++ b/consensus/state_test.go
@@ -184,7 +184,7 @@ func TestBadProposal(t *testing.T) {
 	height, round := cs1.Height, cs1.Round
 	vs2 := vss[1]

-	partSize := cs1.state.Params.BlockPartSizeBytes
+	partSize := cs1.state.ConsensusParams.BlockPartSizeBytes

 	proposalCh := subscribe(cs1.eventBus, types.EventQueryCompleteProposal)
 	voteCh := subscribe(cs1.eventBus, types.EventQueryVote)
@@ -339,7 +339,7 @@ func TestLockNoPOL(t *testing.T) {
 	vs2 := vss[1]
 	height := cs1.Height

-	partSize := cs1.state.Params.BlockPartSizeBytes
+	partSize := cs1.state.ConsensusParams.BlockPartSizeBytes

 	timeoutProposeCh := subscribe(cs1.eventBus, types.EventQueryTimeoutPropose)
 	timeoutWaitCh := subscribe(cs1.eventBus, types.EventQueryTimeoutWait)
@@ -507,7 +507,7 @@ func TestLockPOLRelock(t *testing.T) {
 	cs1, vss := randConsensusState(4)
 	vs2, vs3, vs4 := vss[1], vss[2], vss[3]

-	partSize := cs1.state.Params.BlockPartSizeBytes
+	partSize := cs1.state.ConsensusParams.BlockPartSizeBytes

 	timeoutProposeCh := subscribe(cs1.eventBus, types.EventQueryTimeoutPropose)
 	timeoutWaitCh := subscribe(cs1.eventBus, types.EventQueryTimeoutWait)
@@ -622,7 +622,7 @@ func TestLockPOLUnlock(t *testing.T) {
 	cs1, vss := randConsensusState(4)
 	vs2, vs3, vs4 := vss[1], vss[2], vss[3]

-	partSize := cs1.state.Params.BlockPartSizeBytes
+	partSize := cs1.state.ConsensusParams.BlockPartSizeBytes

 	proposalCh := subscribe(cs1.eventBus, types.EventQueryCompleteProposal)
 	timeoutProposeCh := subscribe(cs1.eventBus, types.EventQueryTimeoutPropose)
@@ -719,7 +719,7 @@ func TestLockPOLSafety1(t *testing.T) {
 	cs1, vss := randConsensusState(4)
 	vs2, vs3, vs4 := vss[1], vss[2], vss[3]

-	partSize := cs1.state.Params.BlockPartSizeBytes
+	partSize := cs1.state.ConsensusParams.BlockPartSizeBytes

 	proposalCh := subscribe(cs1.eventBus, types.EventQueryCompleteProposal)
 	timeoutProposeCh := subscribe(cs1.eventBus, types.EventQueryTimeoutPropose)
@@ -842,7 +842,7 @@ func TestLockPOLSafety2(t *testing.T) {
 	cs1, vss := randConsensusState(4)
 	vs2, vs3, vs4 := vss[1], vss[2], vss[3]

-	partSize := cs1.state.Params.BlockPartSizeBytes
+	partSize := cs1.state.ConsensusParams.BlockPartSizeBytes

 	proposalCh := subscribe(cs1.eventBus, types.EventQueryCompleteProposal)
 	timeoutProposeCh := subscribe(cs1.eventBus, types.EventQueryTimeoutPropose)
@@ -1021,7 +1021,7 @@ func TestHalt1(t *testing.T) {
 	cs1, vss := randConsensusState(4)
 	vs2, vs3, vs4 := vss[1], vss[2], vss[3]

-	partSize := cs1.state.Params.BlockPartSizeBytes
+	partSize := cs1.state.ConsensusParams.BlockPartSizeBytes

 	proposalCh := subscribe(cs1.eventBus, types.EventQueryCompleteProposal)
 	timeoutWaitCh := subscribe(cs1.eventBus, types.EventQueryTimeoutWait)
--- a/consensus/wal.go
+++ b/consensus/wal.go
@@ -18,7 +18,7 @@ import (
 )

 const (
-	// must be greater than params.BlockGossipParams.BlockPartSizeBytes + a few bytes
+	// must be greater than params.BlockGossip.BlockPartSizeBytes + a few bytes
 	maxMsgSizeBytes = 1024 * 1024 // 1MB
 )

--- a/consensus/wal_generator.go
+++ b/consensus/wal_generator.go
@@ -35,7 +35,6 @@ func WALWithNBlocks(numBlocks int) (data []byte, err error) {
 	logger := log.TestingLogger().With("wal_generator", "wal_generator")
 	logger.Info("generating WAL (last height msg excluded)", "numBlocks", numBlocks)

-
 	/////////////////////////////////////////////////////////////////////////////
 	// COPY PASTE FROM node.go WITH A FEW MODIFICATIONS
 	// NOTE: we can't import node package because of circular dependency
@@ -95,7 +94,7 @@ func WALWithNBlocks(numBlocks int) (data []byte, err error) {
 		wr.Flush()
 		return b.Bytes(), nil
 	case <-time.After(1 * time.Minute):
-    wr.Flush()
+		wr.Flush()
 		return b.Bytes(), fmt.Errorf("waited too long for tendermint to produce %d blocks (grep logs for `wal_generator`)", numBlocks)
 	}
 }
@@ -147,7 +146,7 @@ type byteBufferWAL struct {
 	heightToStop      int64
 	signalWhenStopsTo chan<- struct{}

-	logger            log.Logger
+	logger log.Logger
 }

 // needed for determinism
--- a/docs/architecture/adr-005-consensus-params.md
+++ b/docs/architecture/adr-005-consensus-params.md
@@ -22,30 +22,30 @@ The parameters are used to determine the validity of a block (and tx) via the un

 ```
 type ConsensusParams struct {
-    BlockSizeParams
-    TxSizeParams
-    BlockGossipParams
+    BlockSize
+    TxSize
+    BlockGossip
 }

-type BlockSizeParams struct {
+type BlockSize struct {
    MaxBytes int
    MaxTxs int
    MaxGas int
 }

-type TxSizeParams struct {
+type TxSize struct {
    MaxBytes int
    MaxGas int
 }

-type BlockGossipParams struct {
+type BlockGossip struct {
    BlockPartSizeBytes int
 }
 ```

 The `ConsensusParams` can evolve over time by adding new structs that cover different aspects of the consensus rules.

-The `BlockPartSizeBytes` and the `BlockSizeParams.MaxBytes` are enforced to be greater than 0. 
+The `BlockPartSizeBytes` and the `BlockSize.MaxBytes` are enforced to be greater than 0. 
 The former because we need a part size, the latter so that we always have at least some sanity check over the size of blocks.

 ### ABCI
@@ -58,7 +58,7 @@ like the BlockPartSize, that the app shouldn't really know about.

 #### EndBlock

-The EndBlock response includes a `ConsensusParams`, which includes BlockSizeParams and TxSizeParams, but not BlockGossipParams.
+The EndBlock response includes a `ConsensusParams`, which includes BlockSize and TxSize, but not BlockGossip.
 Other param struct can be added to `ConsensusParams` in the future.
 The `0` value is used to denote no change. 
 Any other value will update that parameter in the `State.ConsensusParams`, to be applied for the next block.
@@ -82,4 +82,5 @@ Proposed.

 ### Neutral

- The TxSizeParams, which checks validity, may be in conflict with the config's `max_block_size_tx`, which determines proposal sizes
+- The TxSize, which checks validity, may be in conflict with the config's `max_block_size_tx`, which determines proposal sizes
+
--- a/glide.lock
+++ b/glide.lock
@@ -1,5 +1,5 @@
-hash: f420f1f858100218dad50997d939eaaf129ff654a0648a47ddc60d626ab0b8e9
-updated: 2017-12-10T05:37:46.41123196Z
+hash: bd982742a0aee39426f3866914a59f7c47e68dc8dedb87219e2099c0d9c19f7e
+updated: 2017-12-21T17:45:25.372327218Z
 imports:
 - name: github.com/btcsuite/btcd
  version: 2e60448ffcc6bf78332d1fe590260095f554dd78
@@ -10,7 +10,7 @@ imports:
 - name: github.com/fsnotify/fsnotify
  version: 4da3e2cfbabc9f751898f250b49f2439785783a1
 - name: github.com/go-kit/kit
-  version: e3b2152e0063c5f05efea89ecbe297852af2a92d
+  version: 953e747656a7bbb5e1f998608b460458958b70cc
  subpackages:
  - log
  - log/level
@@ -64,17 +64,19 @@ imports:
 - name: github.com/kr/logfmt
  version: b84e30acd515aadc4b783ad4ff83aff3299bdfe0
 - name: github.com/magiconair/properties
-  version: 49d762b9817ba1c2e9d0c69183c2b4a8b8f1d934
+  version: 8d7837e64d3c1ee4e54a880c5a920ab4316fc90a
 - name: github.com/mitchellh/mapstructure
  version: 06020f85339e21b2478f756a78e295255ffa4d6a
+- name: github.com/pelletier/go-buffruneio
+  version: c37440a7cf42ac63b919c752ca73a85067e05992
 - name: github.com/pelletier/go-toml
-  version: 4e9e0ee19b60b13eb79915933f44d8ed5f268bdd
+  version: b8b5e7696574464b2f9bf303a7b37781bb52889f
 - name: github.com/pkg/errors
  version: 645ef00459ed84a119197bfb8d8205042c6df63d
 - name: github.com/rcrowley/go-metrics
-  version: e181e095bae94582363434144c61a9653aff6e50
+  version: 1f30fe9094a513ce4c700b9a54458bbb0c96996c
 - name: github.com/spf13/afero
-  version: 8d919cbe7e2627e417f3e45c3c0e489a5b7e2536
+  version: 5660eeed305fe5f69c8fc6cf899132a459a97064
  subpackages:
  - mem
 - name: github.com/spf13/cast
@@ -88,7 +90,7 @@ imports:
 - name: github.com/spf13/viper
  version: 25b30aa063fc18e48662b86996252eabdcf2f0c7
 - name: github.com/syndtr/goleveldb
-  version: adf24ef3f94bd13ec4163060b21a5678f22b429b
+  version: 34011bf325bce385408353a30b101fe5e923eb6e
  subpackages:
  - leveldb
  - leveldb/cache
@@ -103,7 +105,7 @@ imports:
  - leveldb/table
  - leveldb/util
 - name: github.com/tendermint/abci
-  version: fca2b508c185b855af1446ec4afc19bdfc7b315d
+  version: e4b9f1abe794a2117a59738a1294e09b46d0fa00
  subpackages:
  - client
  - example/code
@@ -129,7 +131,7 @@ imports:
  subpackages:
  - iavl
 - name: github.com/tendermint/tmlibs
-  version: a483e1ff486b577ba94e6a20f08bf52fbb7bff14
+  version: e236218516289f91bde3273e99fe5c1fc20eb304
  subpackages:
  - autofile
  - cli
@@ -144,7 +146,7 @@ imports:
  - pubsub/query
  - test
 - name: golang.org/x/crypto
-  version: 94eea52f7b742c7cbe0b03b22f0c4c8631ece122
+  version: d585fd2cc9195196078f516b69daff6744ef5e84
  subpackages:
  - curve25519
  - nacl/box
@@ -155,7 +157,7 @@ imports:
  - ripemd160
  - salsa20/salsa
 - name: golang.org/x/net
-  version: a8b9294777976932365dabb6640cf1468d95c70f
+  version: d866cfc389cec985d6fda2859936a575a55a3ab6
  subpackages:
  - context
  - http2
@@ -165,18 +167,18 @@ imports:
  - lex/httplex
  - trace
 - name: golang.org/x/sys
-  version: 8b4580aae2a0dd0c231a45d3ccb8434ff533b840
+  version: d818ba11af4465e00c1998bd3f8a55603b422290
  subpackages:
  - unix
 - name: golang.org/x/text
-  version: 75cc3cad82b5f47d3fb229ddda8c5167da14f294
+  version: eb22672bea55af56d225d4e35405f4d2e9f062a0
  subpackages:
  - secure/bidirule
  - transform
  - unicode/bidi
  - unicode/norm
 - name: google.golang.org/genproto
-  version: 7f0da29060c682909f650ad8ed4e515bd74fa12a
+  version: a8101f21cf983e773d0c1133ebc5424792003214
  subpackages:
  - googleapis/rpc/status
 - name: google.golang.org/grpc
@@ -199,9 +201,9 @@ imports:
  - tap
  - transport
 - name: gopkg.in/go-playground/validator.v9
-  version: 61caf9d3038e1af346dbf5c2e16f6678e1548364
+  version: b1f51f36f1c98cc97f777d6fc9d4b05eaa0cabb5
 - name: gopkg.in/yaml.v2
-  version: 287cf08546ab5e7e37d55a84f7ed3fd1db036de5
+  version: eb3733d160e74a9c7e442f435eb3bea458e1d19f
 testImports:
 - name: github.com/davecgh/go-spew
  version: 04cdfd42973bb9c8589fd6a731800cf222fde1a9
--- a/glide.yaml
+++ b/glide.yaml
@@ -18,7 +18,7 @@ import:
 - package: github.com/spf13/viper
  version: v1.0.0
 - package: github.com/tendermint/abci
-  version: ~v0.8.0
+  version: develop
  subpackages:
  - client
  - example/dummy
@@ -34,7 +34,7 @@ import:
  subpackages:
  - iavl
 - package: github.com/tendermint/tmlibs
-  version: e4ef2835f0081c2ece83b9c1f777cf071f956e81
+  version: develop
  subpackages:
  - autofile
  - cli
--- a/lite/dynamic_test.go
+++ b/lite/dynamic_test.go
@@ -46,7 +46,7 @@ func TestDynamicCert(t *testing.T) {

 	for _, tc := range cases {
 		check := tc.keys.GenCommit(chainID, tc.height, nil, tc.vals,
-			[]byte("bar"), tc.first, tc.last)
+			[]byte("bar"), []byte("params"), tc.first, tc.last)
 		err := cert.Certify(check)
 		if tc.proper {
 			assert.Nil(err, "%+v", err)
@@ -71,7 +71,7 @@ func TestDynamicUpdate(t *testing.T) {

 	// one valid block to give us a sense of time
 	h := int64(100)
-	good := keys.GenCommit(chainID, h, nil, vals, []byte("foo"), 0, len(keys))
+	good := keys.GenCommit(chainID, h, nil, vals, []byte("foo"), []byte("params"), 0, len(keys))
 	err := cert.Certify(good)
 	require.Nil(err, "%+v", err)

@@ -109,7 +109,7 @@ func TestDynamicUpdate(t *testing.T) {

 	for _, tc := range cases {
 		fc := tc.keys.GenFullCommit(chainID, tc.height, nil, tc.vals,
-			[]byte("bar"), tc.first, tc.last)
+			[]byte("bar"), []byte("params"), tc.first, tc.last)
 		err := cert.Update(fc)
 		if tc.proper {
 			assert.Nil(err, "%d: %+v", tc.height, err)
--- a/lite/files/commit_test.go
+++ b/lite/files/commit_test.go
@@ -29,7 +29,7 @@ func TestSerializeFullCommits(t *testing.T) {
 	// build a fc
 	keys := lite.GenValKeys(5)
 	vals := keys.ToValidators(10, 0)
-	fc := keys.GenFullCommit(chainID, h, nil, vals, appHash, 0, 5)
+	fc := keys.GenFullCommit(chainID, h, nil, vals, appHash, []byte("params"), 0, 5)

 	require.Equal(h, fc.Height())
 	require.Equal(vals.Hash(), fc.ValidatorsHash())
--- a/lite/files/provider_test.go
+++ b/lite/files/provider_test.go
@@ -46,7 +46,7 @@ func TestFileProvider(t *testing.T) {
 		// (10, 0), (10, 1), (10, 1), (10, 2), (10, 2), ...
 		vals := keys.ToValidators(10, int64(count/2))
 		h := int64(20 + 10*i)
-		check := keys.GenCommit(chainID, h, nil, vals, appHash, 0, 5)
+		check := keys.GenCommit(chainID, h, nil, vals, appHash, []byte("params"), 0, 5)
 		seeds[i] = lite.NewFullCommit(check, vals)
 	}

--- a/lite/helpers.go
+++ b/lite/helpers.go
@@ -110,7 +110,7 @@ func makeVote(header *types.Header, vals *types.ValidatorSet, key crypto.PrivKey
 // Silences warning that vals can also be merkle.Hashable
 // nolint: interfacer
 func genHeader(chainID string, height int64, txs types.Txs,
-	vals *types.ValidatorSet, appHash []byte) *types.Header {
+	vals *types.ValidatorSet, appHash, consHash []byte) *types.Header {

 	return &types.Header{
 		ChainID:  chainID,
@@ -123,14 +123,15 @@ func genHeader(chainID string, height int64, txs types.Txs,
 		ValidatorsHash: vals.Hash(),
 		DataHash:       txs.Hash(),
 		AppHash:        appHash,
+		ConsensusHash:  consHash,
 	}
 }

 // GenCommit calls genHeader and signHeader and combines them into a Commit.
 func (v ValKeys) GenCommit(chainID string, height int64, txs types.Txs,
-	vals *types.ValidatorSet, appHash []byte, first, last int) Commit {
+	vals *types.ValidatorSet, appHash, consHash []byte, first, last int) Commit {

-	header := genHeader(chainID, height, txs, vals, appHash)
+	header := genHeader(chainID, height, txs, vals, appHash, consHash)
 	check := Commit{
 		Header: header,
 		Commit: v.signHeader(header, first, last),
@@ -140,9 +141,9 @@ func (v ValKeys) GenCommit(chainID string, height int64, txs types.Txs,

 // GenFullCommit calls genHeader and signHeader and combines them into a Commit.
 func (v ValKeys) GenFullCommit(chainID string, height int64, txs types.Txs,
-	vals *types.ValidatorSet, appHash []byte, first, last int) FullCommit {
+	vals *types.ValidatorSet, appHash, consHash []byte, first, last int) FullCommit {

-	header := genHeader(chainID, height, txs, vals, appHash)
+	header := genHeader(chainID, height, txs, vals, appHash, consHash)
 	commit := Commit{
 		Header: header,
 		Commit: v.signHeader(header, first, last),
--- a/lite/inquirer_test.go
+++ b/lite/inquirer_test.go
@@ -22,6 +22,7 @@ func TestInquirerValidPath(t *testing.T) {

 	// construct a bunch of commits, each with one more height than the last
 	chainID := "inquiry-test"
+	consHash := []byte("params")
 	count := 50
 	commits := make([]lite.FullCommit, count)
 	for i := 0; i < count; i++ {
@@ -30,7 +31,7 @@ func TestInquirerValidPath(t *testing.T) {
 		vals := keys.ToValidators(vote, 0)
 		h := int64(20 + 10*i)
 		appHash := []byte(fmt.Sprintf("h=%d", h))
-		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, 0, len(keys))
+		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, consHash, 0, len(keys))
 	}

 	// initialize a certifier with the initial state
@@ -69,6 +70,7 @@ func TestInquirerMinimalPath(t *testing.T) {

 	// construct a bunch of commits, each with one more height than the last
 	chainID := "minimal-path"
+	consHash := []byte("other-params")
 	count := 12
 	commits := make([]lite.FullCommit, count)
 	for i := 0; i < count; i++ {
@@ -77,7 +79,7 @@ func TestInquirerMinimalPath(t *testing.T) {
 		vals := keys.ToValidators(vote, 0)
 		h := int64(5 + 10*i)
 		appHash := []byte(fmt.Sprintf("h=%d", h))
-		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, 0, len(keys))
+		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, consHash, 0, len(keys))
 	}

 	// initialize a certifier with the initial state
@@ -117,6 +119,7 @@ func TestInquirerVerifyHistorical(t *testing.T) {
 	// construct a bunch of commits, each with one more height than the last
 	chainID := "inquiry-test"
 	count := 10
+	consHash := []byte("special-params")
 	commits := make([]lite.FullCommit, count)
 	for i := 0; i < count; i++ {
 		// extend the keys by 1 each time
@@ -124,7 +127,7 @@ func TestInquirerVerifyHistorical(t *testing.T) {
 		vals := keys.ToValidators(vote, 0)
 		h := int64(20 + 10*i)
 		appHash := []byte(fmt.Sprintf("h=%d", h))
-		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, 0, len(keys))
+		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, consHash, 0, len(keys))
 	}

 	// initialize a certifier with the initial state
--- a/lite/performance_test.go
+++ b/lite/performance_test.go
@@ -33,7 +33,7 @@ func benchmarkGenCommit(b *testing.B, keys lite.ValKeys) {
 	for i := 0; i < b.N; i++ {
 		h := int64(1 + i)
 		appHash := []byte(fmt.Sprintf("h=%d", h))
-		keys.GenCommit(chainID, h, nil, vals, appHash, 0, len(keys))
+		keys.GenCommit(chainID, h, nil, vals, appHash, []byte("params"), 0, len(keys))
 	}
 }

@@ -105,7 +105,7 @@ func benchmarkCertifyCommit(b *testing.B, keys lite.ValKeys) {
 	chainID := "bench-certify"
 	vals := keys.ToValidators(20, 10)
 	cert := lite.NewStatic(chainID, vals)
-	check := keys.GenCommit(chainID, 123, nil, vals, []byte("foo"), 0, len(keys))
+	check := keys.GenCommit(chainID, 123, nil, vals, []byte("foo"), []byte("params"), 0, len(keys))
 	for i := 0; i < b.N; i++ {
 		err := cert.Certify(check)
 		if err != nil {
--- a/lite/provider_test.go
+++ b/lite/provider_test.go
@@ -58,7 +58,7 @@ func checkProvider(t *testing.T, p lite.Provider, chainID, app string) {
 		// (10, 0), (10, 1), (10, 1), (10, 2), (10, 2), ...
 		vals := keys.ToValidators(10, int64(count/2))
 		h := int64(20 + 10*i)
-		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, 0, 5)
+		commits[i] = keys.GenFullCommit(chainID, h, nil, vals, appHash, []byte("params"), 0, 5)
 	}

 	// check provider is empty
@@ -129,7 +129,7 @@ func TestCacheGetsBestHeight(t *testing.T) {
 	for i := 0; i < count; i++ {
 		vals := keys.ToValidators(10, int64(count/2))
 		h := int64(10 * (i + 1))
-		fc := keys.GenFullCommit(chainID, h, nil, vals, appHash, 0, 5)
+		fc := keys.GenFullCommit(chainID, h, nil, vals, appHash, []byte("params"), 0, 5)
 		err := p2.StoreCommit(fc)
 		require.NoError(err)
 	}
--- a/lite/static_test.go
+++ b/lite/static_test.go
@@ -44,7 +44,7 @@ func TestStaticCert(t *testing.T) {

 	for _, tc := range cases {
 		check := tc.keys.GenCommit(chainID, tc.height, nil, tc.vals,
-			[]byte("foo"), tc.first, tc.last)
+			[]byte("foo"), []byte("params"), tc.first, tc.last)
 		err := cert.Certify(check)
 		if tc.proper {
 			assert.Nil(err, "%+v", err)
--- a/rpc/test/helpers.go
+++ b/rpc/test/helpers.go
@@ -3,7 +3,6 @@ package rpctest
 import (
 	"context"
 	"fmt"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"strings"
@@ -11,6 +10,8 @@ import (
 	"github.com/tendermint/tmlibs/log"

 	abci "github.com/tendermint/abci/types"
+	cmn "github.com/tendermint/tmlibs/common"
+
 	cfg "github.com/tendermint/tendermint/config"
 	nm "github.com/tendermint/tendermint/node"
 	"github.com/tendermint/tendermint/proxy"
@@ -57,9 +58,7 @@ func makePathname() string {
 }

 func randPort() int {
-	// returns between base and base + spread
-	base, spread := 20000, 20000
-	return base + rand.Intn(spread)
+	return int(cmn.RandUint16()/2 + 10000)
 }

 func makeAddrs() (string, string, string) {
--- a/state/errors.go
+++ b/state/errors.go
@@ -37,6 +37,10 @@ type (
 	ErrNoValSetForHeight struct {
 		Height int64
 	}
+
+	ErrNoConsensusParamsForHeight struct {
+		Height int64
+	}
 )

 func (e ErrUnknownBlock) Error() string {
@@ -61,3 +65,7 @@ func (e ErrStateMismatch) Error() string {
 func (e ErrNoValSetForHeight) Error() string {
 	return cmn.Fmt("Could not find validator set for height #%d", e.Height)
 }
+
+func (e ErrNoConsensusParamsForHeight) Error() string {
+	return cmn.Fmt("Could not find consensus params for height #%d", e.Height)
+}
--- a/state/execution.go
+++ b/state/execution.go
@@ -1,6 +1,7 @@
 package state

 import (
+	"bytes"
 	"errors"
 	"fmt"

@@ -111,11 +112,11 @@ func execBlockOnProxyApp(txEventPublisher types.TxEventPublisher, proxyAppConn p
 		return nil, err
 	}

-	valDiff := abciResponses.EndBlock.Diffs
+	valUpdates := abciResponses.EndBlock.ValidatorUpdates

 	logger.Info("Executed block", "height", block.Height, "validTxs", validTxs, "invalidTxs", invalidTxs)
-	if len(valDiff) > 0 {
-		logger.Info("Update to validator set", "updates", abci.ValidatorsString(valDiff))
+	if len(valUpdates) > 0 {
+		logger.Info("Updates to validators", "updates", abci.ValidatorsString(valUpdates))
 	}

 	return abciResponses, nil
@@ -184,26 +185,69 @@ func (s *State) ValidateBlock(block *types.Block) error {
 	return s.validateBlock(block)
 }

-func (s *State) validateBlock(block *types.Block) error {
+// MakeBlock builds a block with the given txs and commit from the current state.
+func (s *State) MakeBlock(height int64, txs []types.Tx, commit *types.Commit) (*types.Block, *types.PartSet) {
+	// build base block
+	block := types.MakeBlock(height, txs, commit)
+
+	// fill header with state data
+	block.ChainID = s.ChainID
+	block.TotalTxs = s.LastBlockTotalTx + block.NumTxs
+	block.LastBlockID = s.LastBlockID
+	block.ValidatorsHash = s.Validators.Hash()
+	block.AppHash = s.AppHash
+	block.ConsensusHash = s.LastConsensusParams.Hash()
+
+	return block, block.MakePartSet(s.ConsensusParams.BlockGossip.BlockPartSizeBytes)
+}
+
+func (s *State) validateBlock(b *types.Block) error {
 	// Basic block validation.
-	err := block.ValidateBasic(s.ChainID, s.LastBlockHeight,
-		s.LastBlockTotalTx, s.LastBlockID, s.LastBlockTime, s.AppHash)
-	if err != nil {
+	if err := b.ValidateBasic(); err != nil {
 		return err
 	}

+	if b.ChainID != s.ChainID {
+		return fmt.Errorf("Wrong Block.Header.ChainID. Expected %v, got %v", s.ChainID, b.ChainID)
+	}
+	if b.Height != s.LastBlockHeight+1 {
+		return fmt.Errorf("Wrong Block.Header.Height. Expected %v, got %v", s.LastBlockHeight+1, b.Height)
+	}
+	/*	TODO: Determine bounds for Time
+		See blockchain/reactor "stopSyncingDurationMinutes"
+
+		if !b.Time.After(lastBlockTime) {
+			return errors.New("Invalid Block.Header.Time")
+		}
+	*/
+
+	newTxs := int64(len(b.Data.Txs))
+	if b.TotalTxs != s.LastBlockTotalTx+newTxs {
+		return fmt.Errorf("Wrong Block.Header.TotalTxs. Expected %v, got %v", s.LastBlockTotalTx+newTxs, b.TotalTxs)
+	}
+	if !b.LastBlockID.Equals(s.LastBlockID) {
+		return fmt.Errorf("Wrong Block.Header.LastBlockID.  Expected %v, got %v", s.LastBlockID, b.LastBlockID)
+	}
+
+	if !bytes.Equal(b.AppHash, s.AppHash) {
+		return fmt.Errorf("Wrong Block.Header.AppHash.  Expected %X, got %v", s.AppHash, b.AppHash)
+	}
+	if !bytes.Equal(b.ConsensusHash, s.LastConsensusParams.Hash()) {
+		return fmt.Errorf("Wrong Block.Header.ConsensusHash.  Expected %X, got %v", s.LastConsensusParams.Hash(), b.ConsensusHash)
+	}
+
 	// Validate block LastCommit.
-	if block.Height == 1 {
-		if len(block.LastCommit.Precommits) != 0 {
+	if b.Height == 1 {
+		if len(b.LastCommit.Precommits) != 0 {
 			return errors.New("Block at height 1 (first block) should have no LastCommit precommits")
 		}
 	} else {
-		if len(block.LastCommit.Precommits) != s.LastValidators.Size() {
+		if len(b.LastCommit.Precommits) != s.LastValidators.Size() {
 			return errors.New(cmn.Fmt("Invalid block commit size. Expected %v, got %v",
-				s.LastValidators.Size(), len(block.LastCommit.Precommits)))
+				s.LastValidators.Size(), len(b.LastCommit.Precommits)))
 		}
 		err := s.LastValidators.VerifyCommit(
-			s.ChainID, s.LastBlockID, block.Height-1, block.LastCommit)
+			s.ChainID, s.LastBlockID, b.Height-1, b.LastCommit)
 		if err != nil {
 			return err
 		}
@@ -235,7 +279,10 @@ func (s *State) ApplyBlock(txEventPublisher types.TxEventPublisher, proxyAppConn
 	fail.Fail() // XXX

 	// now update the block and validators
-	s.SetBlockAndValidators(block.Header, partsHeader, abciResponses)
+	err = s.SetBlockAndValidators(block.Header, partsHeader, abciResponses)
+	if err != nil {
+		return fmt.Errorf("Commit failed for application: %v", err)
+	}

 	// lock mempool, commit state, update mempoool
 	err = s.CommitStateUpdateMempool(proxyAppConn, block, mempool)
--- a/state/execution_test.go
+++ b/state/execution_test.go
@@ -23,6 +23,52 @@ var (
 	nTxsPerBlock = 10
 )

+func TestValidateBlock(t *testing.T) {
+	state := state()
+	state.SetLogger(log.TestingLogger())
+
+	// proper block must pass
+	block := makeBlock(state, 1)
+	err := state.ValidateBlock(block)
+	require.NoError(t, err)
+
+	// wrong chain fails
+	block = makeBlock(state, 1)
+	block.ChainID = "not-the-real-one"
+	err = state.ValidateBlock(block)
+	require.Error(t, err)
+
+	// wrong height fails
+	block = makeBlock(state, 1)
+	block.Height += 10
+	err = state.ValidateBlock(block)
+	require.Error(t, err)
+
+	// wrong total tx fails
+	block = makeBlock(state, 1)
+	block.TotalTxs += 10
+	err = state.ValidateBlock(block)
+	require.Error(t, err)
+
+	// wrong blockid fails
+	block = makeBlock(state, 1)
+	block.LastBlockID.PartsHeader.Total += 10
+	err = state.ValidateBlock(block)
+	require.Error(t, err)
+
+	// wrong app hash fails
+	block = makeBlock(state, 1)
+	block.AppHash = []byte("wrong app hash")
+	err = state.ValidateBlock(block)
+	require.Error(t, err)
+
+	// wrong consensus hash fails
+	block = makeBlock(state, 1)
+	block.ConsensusHash = []byte("wrong consensus hash")
+	err = state.ValidateBlock(block)
+	require.Error(t, err)
+}
+
 func TestApplyBlock(t *testing.T) {
 	cc := proxy.NewLocalClientCreator(dummy.NewDummyApplication())
 	proxyApp := proxy.NewAppConns(cc, nil)
@@ -33,7 +79,7 @@ func TestApplyBlock(t *testing.T) {
 	state := state()
 	state.SetLogger(log.TestingLogger())

-	block := makeBlock(1, state)
+	block := makeBlock(state, 1)

 	err = state.ApplyBlock(types.NopEventBus{}, proxyApp.Consensus(), block, block.MakePartSet(testPartSize).Header(), types.MockMempool{})
 	require.Nil(t, err)
@@ -79,10 +125,7 @@ func TestBeginBlockAbsentValidators(t *testing.T) {
 	for _, tc := range testCases {
 		lastCommit := &types.Commit{BlockID: prevBlockID, Precommits: tc.lastCommitPrecommits}

-		valHash := state.Validators.Hash()
-		block, _ := types.MakeBlock(2, chainID, makeTxs(2), state.LastBlockTotalTx, lastCommit,
-			prevBlockID, valHash, state.AppHash, testPartSize)
-
+		block, _ := state.MakeBlock(2, makeTxs(2), lastCommit)
 		_, err = ExecCommitBlock(proxyApp.Consensus(), block, log.TestingLogger(), lastValidators)
 		require.Nil(t, err, tc.desc)

@@ -112,15 +155,8 @@ func state() *State {
 	return s
 }

-func makeBlock(height int64, state *State) *types.Block {
-	prevHash := state.LastBlockID.Hash
-	prevParts := types.PartSetHeader{}
-	valHash := state.Validators.Hash()
-	prevBlockID := types.BlockID{prevHash, prevParts}
-	block, _ := types.MakeBlock(height, chainID,
-		makeTxs(height), state.LastBlockTotalTx,
-		new(types.Commit), prevBlockID, valHash,
-		state.AppHash, testPartSize)
+func makeBlock(state *State, height int64) *types.Block {
+	block, _ := state.MakeBlock(height, makeTxs(state.LastBlockHeight), new(types.Commit))
 	return block
 }

--- a/state/state.go
+++ b/state/state.go
@@ -18,6 +18,7 @@ import (
 	"github.com/tendermint/tendermint/types"
 )

+// database keys
 var (
 	stateKey         = []byte("stateKey")
 	abciResponsesKey = []byte("abciResponsesKey")
@@ -27,37 +28,50 @@ func calcValidatorsKey(height int64) []byte {
 	return []byte(cmn.Fmt("validatorsKey:%v", height))
 }

+func calcConsensusParamsKey(height int64) []byte {
+	return []byte(cmn.Fmt("consensusParamsKey:%v", height))
+}
+
 //-----------------------------------------------------------------------------

-// State represents the latest committed state of the Tendermint consensus,
-// including the last committed block and validator set.
-// Newly committed blocks are validated and executed against the State.
+// State is a short description of the latest committed block of the Tendermint consensus.
+// It keeps all information necessary to validate new blocks,
+// including the last validator set and the consensus params.
+// All fields are exposed so the struct can be easily serialized,
+// but the fields should only be changed by calling state.SetBlockAndValidators.
 // NOTE: not goroutine-safe.
 type State struct {
 	// mtx for writing to db
 	mtx sync.Mutex
 	db  dbm.DB

+	// Immutable
 	ChainID string
-	// Consensus parameters used for validating blocks
-	Params types.ConsensusParams

-	// These fields are updated by SetBlockAndValidators.
+	// Exposed fields are updated by SetBlockAndValidators.
+
 	// LastBlockHeight=0 at genesis (ie. block(H=0) does not exist)
-	// LastValidators is used to validate block.LastCommit.
 	LastBlockHeight  int64
 	LastBlockTotalTx int64
 	LastBlockID      types.BlockID
 	LastBlockTime    time.Time
-	Validators       *types.ValidatorSet
-	LastValidators   *types.ValidatorSet
-	// When a block returns a validator set change via EndBlock,
-	// the change only applies to the next block.
-	// So, if s.LastBlockHeight causes a valset change,
+
+	// LastValidators is used to validate block.LastCommit.
+	// Validators are persisted to the database separately every time they change,
+	// so we can query for historical validator sets.
+	// Note that if s.LastBlockHeight causes a valset change,
 	// we set s.LastHeightValidatorsChanged = s.LastBlockHeight + 1
+	Validators                  *types.ValidatorSet
+	LastValidators              *types.ValidatorSet
 	LastHeightValidatorsChanged int64

-	// AppHash is updated after Commit
+	// Consensus parameters used for validating blocks.
+	// Changes returned by EndBlock and updated after Commit.
+	ConsensusParams                  types.ConsensusParams
+	LastConsensusParams              types.ConsensusParams
+	LastHeightConsensusParamsChanged int64
+
+	// The latest AppHash we've received from calling abci.Commit()
 	AppHash []byte

 	logger log.Logger
@@ -112,18 +126,26 @@ func (s *State) SetLogger(l log.Logger) {
 // Copy makes a copy of the State for mutating.
 func (s *State) Copy() *State {
 	return &State{
-		db:                          s.db,
-		LastBlockHeight:             s.LastBlockHeight,
-		LastBlockTotalTx:            s.LastBlockTotalTx,
-		LastBlockID:                 s.LastBlockID,
-		LastBlockTime:               s.LastBlockTime,
+		db: s.db,
+
+		ChainID: s.ChainID,
+
+		LastBlockHeight:  s.LastBlockHeight,
+		LastBlockTotalTx: s.LastBlockTotalTx,
+		LastBlockID:      s.LastBlockID,
+		LastBlockTime:    s.LastBlockTime,
+
 		Validators:                  s.Validators.Copy(),
 		LastValidators:              s.LastValidators.Copy(),
-		AppHash:                     s.AppHash,
 		LastHeightValidatorsChanged: s.LastHeightValidatorsChanged,
-		logger:  s.logger,
-		ChainID: s.ChainID,
-		Params:  s.Params,
+
+		ConsensusParams:                  s.ConsensusParams,
+		LastConsensusParams:              s.LastConsensusParams,
+		LastHeightConsensusParamsChanged: s.LastHeightConsensusParamsChanged,
+
+		AppHash: s.AppHash,
+
+		logger: s.logger,
 	}
 }

@@ -133,6 +155,7 @@ func (s *State) Save() {
 	defer s.mtx.Unlock()

 	s.saveValidatorsInfo()
+	s.saveConsensusParamsInfo()
 	s.db.SetSync(stateKey, s.Bytes())
 }

@@ -166,13 +189,13 @@ func (s *State) LoadABCIResponses() *ABCIResponses {

 // LoadValidators loads the ValidatorSet for a given height.
 func (s *State) LoadValidators(height int64) (*types.ValidatorSet, error) {
-	valInfo := s.loadValidators(height)
+	valInfo := s.loadValidatorsInfo(height)
 	if valInfo == nil {
 		return nil, ErrNoValSetForHeight{height}
 	}

 	if valInfo.ValidatorSet == nil {
-		valInfo = s.loadValidators(valInfo.LastHeightChanged)
+		valInfo = s.loadValidatorsInfo(valInfo.LastHeightChanged)
 		if valInfo == nil {
 			cmn.PanicSanity(fmt.Sprintf(`Couldn't find validators at height %d as
                        last changed from height %d`, valInfo.LastHeightChanged, height))
@@ -182,7 +205,7 @@ func (s *State) LoadValidators(height int64) (*types.ValidatorSet, error) {
 	return valInfo.ValidatorSet, nil
 }

-func (s *State) loadValidators(height int64) *ValidatorsInfo {
+func (s *State) loadValidatorsInfo(height int64) *ValidatorsInfo {
 	buf := s.db.Get(calcValidatorsKey(height))
 	if len(buf) == 0 {
 		return nil
@@ -217,6 +240,61 @@ func (s *State) saveValidatorsInfo() {
 	s.db.SetSync(calcValidatorsKey(nextHeight), valInfo.Bytes())
 }

+// LoadConsensusParams loads the ConsensusParams for a given height.
+func (s *State) LoadConsensusParams(height int64) (types.ConsensusParams, error) {
+	empty := types.ConsensusParams{}
+
+	paramsInfo := s.loadConsensusParamsInfo(height)
+	if paramsInfo == nil {
+		return empty, ErrNoConsensusParamsForHeight{height}
+	}
+
+	if paramsInfo.ConsensusParams == empty {
+		paramsInfo = s.loadConsensusParamsInfo(paramsInfo.LastHeightChanged)
+		if paramsInfo == nil {
+			cmn.PanicSanity(fmt.Sprintf(`Couldn't find consensus params at height %d as
+                        last changed from height %d`, paramsInfo.LastHeightChanged, height))
+		}
+	}
+
+	return paramsInfo.ConsensusParams, nil
+}
+
+func (s *State) loadConsensusParamsInfo(height int64) *ConsensusParamsInfo {
+	buf := s.db.Get(calcConsensusParamsKey(height))
+	if len(buf) == 0 {
+		return nil
+	}
+
+	paramsInfo := new(ConsensusParamsInfo)
+	r, n, err := bytes.NewReader(buf), new(int), new(error)
+	wire.ReadBinaryPtr(paramsInfo, r, 0, n, err)
+	if *err != nil {
+		// DATA HAS BEEN CORRUPTED OR THE SPEC HAS CHANGED
+		cmn.Exit(cmn.Fmt(`LoadConsensusParams: Data has been corrupted or its spec has changed:
+                %v\n`, *err))
+	}
+	// TODO: ensure that buf is completely read.
+
+	return paramsInfo
+}
+
+// saveConsensusParamsInfo persists the consensus params for the next block to disk.
+// It should be called from s.Save(), right before the state itself is persisted.
+// If the consensus params did not change after processing the latest block,
+// only the last height for which they changed is persisted.
+func (s *State) saveConsensusParamsInfo() {
+	changeHeight := s.LastHeightConsensusParamsChanged
+	nextHeight := s.LastBlockHeight + 1
+	paramsInfo := &ConsensusParamsInfo{
+		LastHeightChanged: changeHeight,
+	}
+	if changeHeight == nextHeight {
+		paramsInfo.ConsensusParams = s.ConsensusParams
+	}
+	s.db.SetSync(calcConsensusParamsKey(nextHeight), paramsInfo.Bytes())
+}
+
 // Equals returns true if the States are identical.
 func (s *State) Equals(s2 *State) bool {
 	return bytes.Equal(s.Bytes(), s2.Bytes())
@@ -230,7 +308,7 @@ func (s *State) Bytes() []byte {
 // SetBlockAndValidators mutates State variables
 // to update block and validators after running EndBlock.
 func (s *State) SetBlockAndValidators(header *types.Header, blockPartsHeader types.PartSetHeader,
-	abciResponses *ABCIResponses) {
+	abciResponses *ABCIResponses) error {

 	// copy the valset so we can apply changes from EndBlock
 	// and update s.LastValidators and s.Validators
@@ -238,11 +316,10 @@ func (s *State) SetBlockAndValidators(header *types.Header, blockPartsHeader typ
 	nextValSet := prevValSet.Copy()

 	// update the validator set with the latest abciResponses
-	if len(abciResponses.EndBlock.Diffs) > 0 {
-		err := updateValidators(nextValSet, abciResponses.EndBlock.Diffs)
+	if len(abciResponses.EndBlock.ValidatorUpdates) > 0 {
+		err := updateValidators(nextValSet, abciResponses.EndBlock.ValidatorUpdates)
 		if err != nil {
-			s.logger.Error("Error changing validator set", "err", err)
-			// TODO: err or carry on?
+			return fmt.Errorf("Error changing validator set: %v", err)
 		}
 		// change results from this height but only applies to the next height
 		s.LastHeightValidatorsChanged = header.Height + 1
@@ -251,24 +328,43 @@ func (s *State) SetBlockAndValidators(header *types.Header, blockPartsHeader typ
 	// Update validator accums and set state variables
 	nextValSet.IncrementAccum(1)

+	// update the params with the latest abciResponses
+	nextParams := s.ConsensusParams
+	if abciResponses.EndBlock.ConsensusParamUpdates != nil {
+		// NOTE: must not mutate s.ConsensusParams
+		nextParams = s.ConsensusParams.Update(abciResponses.EndBlock.ConsensusParamUpdates)
+		err := nextParams.Validate()
+		if err != nil {
+			return fmt.Errorf("Error updating consensus params: %v", err)
+		}
+		// change results from this height but only applies to the next height
+		s.LastHeightConsensusParamsChanged = header.Height + 1
+	}
+
 	s.setBlockAndValidators(header.Height,
 		header.NumTxs,
 		types.BlockID{header.Hash(), blockPartsHeader},
 		header.Time,
-		prevValSet, nextValSet)
-
+		nextValSet,
+		nextParams)
+	return nil
 }

 func (s *State) setBlockAndValidators(height int64,
 	newTxs int64, blockID types.BlockID, blockTime time.Time,
-	prevValSet, nextValSet *types.ValidatorSet) {
+	valSet *types.ValidatorSet,
+	params types.ConsensusParams) {

 	s.LastBlockHeight = height
 	s.LastBlockTotalTx += newTxs
 	s.LastBlockID = blockID
 	s.LastBlockTime = blockTime
-	s.Validators = nextValSet
-	s.LastValidators = prevValSet
+
+	s.LastValidators = s.Validators.Copy()
+	s.Validators = valSet
+
+	s.LastConsensusParams = s.ConsensusParams
+	s.ConsensusParams = params
 }

 // GetValidators returns the last and current validator sets.
@@ -316,6 +412,19 @@ func (valInfo *ValidatorsInfo) Bytes() []byte {
 	return wire.BinaryBytes(*valInfo)
 }

+//-----------------------------------------------------------------------------
+
+// ConsensusParamsInfo represents the latest consensus params, or the last height it changed
+type ConsensusParamsInfo struct {
+	ConsensusParams   types.ConsensusParams
+	LastHeightChanged int64
+}
+
+// Bytes serializes the ConsensusParamsInfo using go-wire
+func (params ConsensusParamsInfo) Bytes() []byte {
+	return wire.BinaryBytes(params)
+}
+
 //------------------------------------------------------------------------
 // Genesis

@@ -369,14 +478,19 @@ func MakeGenesisState(db dbm.DB, genDoc *types.GenesisDoc) (*State, error) {
 		db: db,

 		ChainID: genDoc.ChainID,
-		Params:  *genDoc.ConsensusParams,

-		LastBlockHeight:             0,
-		LastBlockID:                 types.BlockID{},
-		LastBlockTime:               genDoc.GenesisTime,
+		LastBlockHeight: 0,
+		LastBlockID:     types.BlockID{},
+		LastBlockTime:   genDoc.GenesisTime,
+
 		Validators:                  types.NewValidatorSet(validators),
 		LastValidators:              types.NewValidatorSet(nil),
-		AppHash:                     genDoc.AppHash,
 		LastHeightValidatorsChanged: 1,
+
+		ConsensusParams:                  *genDoc.ConsensusParams,
+		LastConsensusParams:              types.ConsensusParams{},
+		LastHeightConsensusParamsChanged: 1,
+
+		AppHash: genDoc.AppHash,
 	}, nil
 }
--- a/state/state_test.go
+++ b/state/state_test.go
@@ -76,11 +76,11 @@ func TestABCIResponsesSaveLoad(t *testing.T) {
 	state.LastBlockHeight++

 	// build mock responses
-	block := makeBlock(2, state)
+	block := makeBlock(state, 2)
 	abciResponses := NewABCIResponses(block)
 	abciResponses.DeliverTx[0] = &abci.ResponseDeliverTx{Data: []byte("foo"), Tags: []*abci.KVPair{}}
 	abciResponses.DeliverTx[1] = &abci.ResponseDeliverTx{Data: []byte("bar"), Log: "ok", Tags: []*abci.KVPair{}}
-	abciResponses.EndBlock = &abci.ResponseEndBlock{Diffs: []*abci.Validator{
+	abciResponses.EndBlock = &abci.ResponseEndBlock{ValidatorUpdates: []*abci.Validator{
 		{
 			PubKey: crypto.GenPrivKeyEd25519().PubKey().Bytes(),
 			Power:  10,
@@ -192,20 +192,144 @@ func TestValidatorChangesSaveLoad(t *testing.T) {
 	}
 }

+// TestConsensusParamsChangesSaveLoad tests saving and loading consensus params with changes.
+func TestConsensusParamsChangesSaveLoad(t *testing.T) {
+	tearDown, _, state := setupTestCase(t)
+	defer tearDown(t)
+	// nolint: vetshadow
+	assert := assert.New(t)
+
+	// change vals at these heights
+	changeHeights := []int64{1, 2, 4, 5, 10, 15, 16, 17, 20}
+	N := len(changeHeights)
+
+	// each valset is just one validator.
+	// create list of them
+	params := make([]types.ConsensusParams, N+1)
+	params[0] = state.ConsensusParams
+	for i := 1; i < N+1; i++ {
+		params[i] = *types.DefaultConsensusParams()
+		params[i].BlockSize.MaxBytes += i
+	}
+
+	// build the params history by running SetBlockAndValidators
+	// with the right params set for each height
+	highestHeight := changeHeights[N-1] + 5
+	changeIndex := 0
+	cp := params[changeIndex]
+	for i := int64(1); i < highestHeight; i++ {
+		// when we get to a change height,
+		// use the next params
+		if changeIndex < len(changeHeights) && i == changeHeights[changeIndex] {
+			changeIndex++
+			cp = params[changeIndex]
+		}
+		header, parts, responses := makeHeaderPartsResponsesParams(state, i, cp)
+		state.SetBlockAndValidators(header, parts, responses)
+		state.saveConsensusParamsInfo()
+	}
+
+	// make all the test cases by using the same params until after the change
+	testCases := make([]paramsChangeTestCase, highestHeight)
+	changeIndex = 0
+	cp = params[changeIndex]
+	for i := int64(1); i < highestHeight+1; i++ {
+		// we we get to the height after a change height
+		// use the next pubkey (note our counter starts at 0 this time)
+		if changeIndex < len(changeHeights) && i == changeHeights[changeIndex]+1 {
+			changeIndex++
+			cp = params[changeIndex]
+		}
+		testCases[i-1] = paramsChangeTestCase{i, cp}
+	}
+
+	for _, testCase := range testCases {
+		p, err := state.LoadConsensusParams(testCase.height)
+		assert.Nil(err, fmt.Sprintf("expected no err at height %d", testCase.height))
+		assert.Equal(testCase.params, p, fmt.Sprintf(`unexpected consensus params at
+                height %d`, testCase.height))
+	}
+}
+
+func makeParams(blockBytes, blockTx, blockGas, txBytes,
+	txGas, partSize int) types.ConsensusParams {
+
+	return types.ConsensusParams{
+		BlockSize: types.BlockSize{
+			MaxBytes: blockBytes,
+			MaxTxs:   blockTx,
+			MaxGas:   int64(blockGas),
+		},
+		TxSize: types.TxSize{
+			MaxBytes: txBytes,
+			MaxGas:   int64(txGas),
+		},
+		BlockGossip: types.BlockGossip{
+			BlockPartSizeBytes: partSize,
+		},
+	}
+}
+
+func TestApplyUpdates(t *testing.T) {
+	initParams := makeParams(1, 2, 3, 4, 5, 6)
+
+	cases := [...]struct {
+		init     types.ConsensusParams
+		updates  *abci.ConsensusParams
+		expected types.ConsensusParams
+	}{
+		0: {initParams, nil, initParams},
+		1: {initParams, &abci.ConsensusParams{}, initParams},
+		2: {initParams,
+			&abci.ConsensusParams{
+				TxSize: &abci.TxSize{
+					MaxBytes: 123,
+				},
+			},
+			makeParams(1, 2, 3, 123, 5, 6)},
+		3: {initParams,
+			&abci.ConsensusParams{
+				BlockSize: &abci.BlockSize{
+					MaxTxs: 44,
+					MaxGas: 55,
+				},
+			},
+			makeParams(1, 44, 55, 4, 5, 6)},
+		4: {initParams,
+			&abci.ConsensusParams{
+				BlockSize: &abci.BlockSize{
+					MaxTxs: 789,
+				},
+				TxSize: &abci.TxSize{
+					MaxGas: 888,
+				},
+				BlockGossip: &abci.BlockGossip{
+					BlockPartSizeBytes: 2002,
+				},
+			},
+			makeParams(1, 789, 3, 4, 888, 2002)},
+	}
+
+	for i, tc := range cases {
+		res := tc.init.Update(tc.updates)
+		assert.Equal(t, tc.expected, res, "case %d", i)
+	}
+}
+
 func makeHeaderPartsResponses(state *State, height int64,
 	pubkey crypto.PubKey) (*types.Header, types.PartSetHeader, *ABCIResponses) {

-	block := makeBlock(height, state)
+	block := makeBlock(state, height)
 	_, val := state.Validators.GetByIndex(0)
 	abciResponses := &ABCIResponses{
 		Height:   height,
-		EndBlock: &abci.ResponseEndBlock{Diffs: []*abci.Validator{}},
+		EndBlock: &abci.ResponseEndBlock{ValidatorUpdates: []*abci.Validator{}},
 	}

 	// if the pubkey is new, remove the old and add the new
 	if !bytes.Equal(pubkey.Bytes(), val.PubKey.Bytes()) {
 		abciResponses.EndBlock = &abci.ResponseEndBlock{
-			Diffs: []*abci.Validator{
+			ValidatorUpdates: []*abci.Validator{
 				{val.PubKey.Bytes(), 0},
 				{pubkey.Bytes(), 10},
 			},
@@ -219,3 +343,19 @@ type valChangeTestCase struct {
 	height int64
 	vals   crypto.PubKey
 }
+
+func makeHeaderPartsResponsesParams(state *State, height int64,
+	params types.ConsensusParams) (*types.Header, types.PartSetHeader, *ABCIResponses) {
+
+	block := makeBlock(state, height)
+	abciResponses := &ABCIResponses{
+		Height:   height,
+		EndBlock: &abci.ResponseEndBlock{ConsensusParamUpdates: types.TM2PB.ConsensusParams(&params)},
+	}
+	return block.Header, types.PartSetHeader{}, abciResponses
+}
+
+type paramsChangeTestCase struct {
+	height int64
+	params types.ConsensusParams
+}
--- a/types/block.go
+++ b/types/block.go
@@ -15,30 +15,21 @@ import (
 )

 // Block defines the atomic unit of a Tendermint blockchain.
+// TODO: add Version byte
 type Block struct {
 	*Header    `json:"header"`
 	*Data      `json:"data"`
 	LastCommit *Commit `json:"last_commit"`
 }

-// MakeBlock returns a new block and corresponding partset from the given information.
-// TODO: Add version information to the Block struct.
-func MakeBlock(height int64, chainID string, txs []Tx,
-	totalTxs int64, commit *Commit,
-	prevBlockID BlockID, valHash, appHash []byte,
-	partSize int) (*Block, *PartSet) {
-
-	newTxs := int64(len(txs))
+// MakeBlock returns a new block with an empty header, except what can be computed from itself.
+// It populates the same set of fields validated by ValidateBasic
+func MakeBlock(height int64, txs []Tx, commit *Commit) *Block {
 	block := &Block{
 		Header: &Header{
-			ChainID:        chainID,
-			Height:         height,
-			Time:           time.Now(),
-			NumTxs:         newTxs,
-			TotalTxs:       totalTxs + newTxs,
-			LastBlockID:    prevBlockID,
-			ValidatorsHash: valHash,
-			AppHash:        appHash, // state merkle root of txs from the previous block.
+			Height: height,
+			Time:   time.Now(),
+			NumTxs: int64(len(txs)),
 		},
 		LastCommit: commit,
 		Data: &Data{
@@ -46,39 +37,18 @@ func MakeBlock(height int64, chainID string, txs []Tx,
 		},
 	}
 	block.FillHeader()
-	return block, block.MakePartSet(partSize)
+	return block
 }

 // ValidateBasic performs basic validation that doesn't involve state data.
-func (b *Block) ValidateBasic(chainID string, lastBlockHeight int64,
-	lastBlockTotalTx int64, lastBlockID BlockID,
-	lastBlockTime time.Time, appHash []byte) error {
-
-	if b.ChainID != chainID {
-		return errors.New(cmn.Fmt("Wrong Block.Header.ChainID. Expected %v, got %v", chainID, b.ChainID))
-	}
-	if b.Height != lastBlockHeight+1 {
-		return errors.New(cmn.Fmt("Wrong Block.Header.Height. Expected %v, got %v", lastBlockHeight+1, b.Height))
-	}
-	/*	TODO: Determine bounds for Time
-		See blockchain/reactor "stopSyncingDurationMinutes"
-
-		if !b.Time.After(lastBlockTime) {
-			return errors.New("Invalid Block.Header.Time")
-		}
-	*/
+// It checks the internal consistency of the block.
+func (b *Block) ValidateBasic() error {
 	newTxs := int64(len(b.Data.Txs))
 	if b.NumTxs != newTxs {
-		return errors.New(cmn.Fmt("Wrong Block.Header.NumTxs. Expected %v, got %v", newTxs, b.NumTxs))
-	}
-	if b.TotalTxs != lastBlockTotalTx+newTxs {
-		return errors.New(cmn.Fmt("Wrong Block.Header.TotalTxs. Expected %v, got %v", lastBlockTotalTx+newTxs, b.TotalTxs))
-	}
-	if !b.LastBlockID.Equals(lastBlockID) {
-		return errors.New(cmn.Fmt("Wrong Block.Header.LastBlockID.  Expected %v, got %v", lastBlockID, b.LastBlockID))
+		return fmt.Errorf("Wrong Block.Header.NumTxs. Expected %v, got %v", newTxs, b.NumTxs)
 	}
 	if !bytes.Equal(b.LastCommitHash, b.LastCommit.Hash()) {
-		return errors.New(cmn.Fmt("Wrong Block.Header.LastCommitHash.  Expected %v, got %v", b.LastCommitHash, b.LastCommit.Hash()))
+		return fmt.Errorf("Wrong Block.Header.LastCommitHash.  Expected %v, got %v", b.LastCommitHash, b.LastCommit.Hash())
 	}
 	if b.Header.Height != 1 {
 		if err := b.LastCommit.ValidateBasic(); err != nil {
@@ -86,12 +56,8 @@ func (b *Block) ValidateBasic(chainID string, lastBlockHeight int64,
 		}
 	}
 	if !bytes.Equal(b.DataHash, b.Data.Hash()) {
-		return errors.New(cmn.Fmt("Wrong Block.Header.DataHash.  Expected %v, got %v", b.DataHash, b.Data.Hash()))
+		return fmt.Errorf("Wrong Block.Header.DataHash.  Expected %v, got %v", b.DataHash, b.Data.Hash())
 	}
-	if !bytes.Equal(b.AppHash, appHash) {
-		return errors.New(cmn.Fmt("Wrong Block.Header.AppHash.  Expected %X, got %v", appHash, b.AppHash))
-	}
-	// NOTE: the AppHash and ValidatorsHash are validated later.
 	return nil
 }

@@ -167,17 +133,26 @@ func (b *Block) StringShort() string {
 //-----------------------------------------------------------------------------

 // Header defines the structure of a Tendermint block header
+// TODO: limit header size
 type Header struct {
-	ChainID        string     `json:"chain_id"`
-	Height         int64      `json:"height"`
-	Time           time.Time  `json:"time"`
-	NumTxs         int64      `json:"num_txs"` // XXX: Can we get rid of this?
-	TotalTxs       int64      `json:"total_txs"`
-	LastBlockID    BlockID    `json:"last_block_id"`
+	// basic block info
+	ChainID string    `json:"chain_id"`
+	Height  int64     `json:"height"`
+	Time    time.Time `json:"time"`
+	NumTxs  int64     `json:"num_txs"`
+
+	// prev block info
+	LastBlockID BlockID `json:"last_block_id"`
+	TotalTxs    int64   `json:"total_txs"`
+
+	// hashes of block data
 	LastCommitHash data.Bytes `json:"last_commit_hash"` // commit from validators from the last block
 	DataHash       data.Bytes `json:"data_hash"`        // transactions
-	ValidatorsHash data.Bytes `json:"validators_hash"`  // validators for the current block
-	AppHash        data.Bytes `json:"app_hash"`         // state after txs from the previous block
+
+	// hashes from the app
+	ValidatorsHash data.Bytes `json:"validators_hash"` // validators for the current block
+	ConsensusHash  data.Bytes `json:"consensus_hash"`  // consensus params for current block
+	AppHash        data.Bytes `json:"app_hash"`        // state after txs from the previous block
 }

 // Hash returns the hash of the header.
@@ -197,6 +172,7 @@ func (h *Header) Hash() data.Bytes {
 		"Data":        h.DataHash,
 		"Validators":  h.ValidatorsHash,
 		"App":         h.AppHash,
+		"Consensus":   h.ConsensusHash,
 	})
 }

@@ -216,6 +192,7 @@ func (h *Header) StringIndented(indent string) string {
 %s  Data:           %v
 %s  Validators:     %v
 %s  App:            %v
+%s  Conensus:            %v
 %s}#%v`,
 		indent, h.ChainID,
 		indent, h.Height,
@@ -227,6 +204,7 @@ func (h *Header) StringIndented(indent string) string {
 		indent, h.DataHash,
 		indent, h.ValidatorsHash,
 		indent, h.AppHash,
+		indent, h.ConsensusHash,
 		indent, h.Hash())
 }

--- a/types/block_test.go
+++ b/types/block_test.go
@@ -2,81 +2,63 @@ package types

 import (
 	"testing"
-	"time"

 	"github.com/stretchr/testify/require"
 	crypto "github.com/tendermint/go-crypto"
+	cmn "github.com/tendermint/tmlibs/common"
 )

 func TestValidateBlock(t *testing.T) {
 	txs := []Tx{Tx("foo"), Tx("bar")}
 	lastID := makeBlockID()
-	valHash := []byte("val")
-	appHash := []byte("app")
 	h := int64(3)

 	voteSet, _, vals := randVoteSet(h-1, 1, VoteTypePrecommit,
 		10, 1)
-	commit, err := makeCommit(lastID, h-1, 1, voteSet, vals)
+	commit, err := MakeCommit(lastID, h-1, 1, voteSet, vals)
 	require.NoError(t, err)

-	block, _ := MakeBlock(h, "hello", txs, 10, commit,
-		lastID, valHash, appHash, 2)
+	block := MakeBlock(h, txs, commit)
 	require.NotNil(t, block)

 	// proper block must pass
-	err = block.ValidateBasic("hello", h-1, 10, lastID, block.Time, appHash)
+	err = block.ValidateBasic()
 	require.NoError(t, err)

-	// wrong chain fails
-	err = block.ValidateBasic("other", h-1, 10, lastID, block.Time, appHash)
+	// tamper with NumTxs
+	block = MakeBlock(h, txs, commit)
+	block.NumTxs += 1
+	err = block.ValidateBasic()
 	require.Error(t, err)

-	// wrong height fails
-	err = block.ValidateBasic("hello", h+4, 10, lastID, block.Time, appHash)
+	// remove 1/2 the commits
+	block = MakeBlock(h, txs, commit)
+	block.LastCommit.Precommits = commit.Precommits[:commit.Size()/2]
+	block.LastCommit.hash = nil // clear hash or change wont be noticed
+	err = block.ValidateBasic()
 	require.Error(t, err)

-	// wrong total tx fails
-	err = block.ValidateBasic("hello", h-1, 15, lastID, block.Time, appHash)
+	// tamper with LastCommitHash
+	block = MakeBlock(h, txs, commit)
+	block.LastCommitHash = []byte("something else")
+	err = block.ValidateBasic()
 	require.Error(t, err)

-	// wrong blockid fails
-	err = block.ValidateBasic("hello", h-1, 10, makeBlockID(), block.Time, appHash)
+	// tamper with data
+	block = MakeBlock(h, txs, commit)
+	block.Data.Txs[0] = Tx("something else")
+	block.Data.hash = nil // clear hash or change wont be noticed
+	err = block.ValidateBasic()
 	require.Error(t, err)

-	// wrong app hash fails
-	err = block.ValidateBasic("hello", h-1, 10, lastID, block.Time, []byte("bad-hash"))
+	// tamper with DataHash
+	block = MakeBlock(h, txs, commit)
+	block.DataHash = cmn.RandBytes(len(block.DataHash))
+	err = block.ValidateBasic()
 	require.Error(t, err)
-
 }

 func makeBlockID() BlockID {
 	blockHash, blockPartsHeader := crypto.CRandBytes(32), PartSetHeader{123, crypto.CRandBytes(32)}
 	return BlockID{blockHash, blockPartsHeader}
 }
-
-func makeCommit(blockID BlockID, height int64, round int,
-	voteSet *VoteSet,
-	validators []*PrivValidatorFS) (*Commit, error) {
-
-	voteProto := &Vote{
-		ValidatorAddress: nil,
-		ValidatorIndex:   -1,
-		Height:           height,
-		Round:            round,
-		Type:             VoteTypePrecommit,
-		BlockID:          blockID,
-		Timestamp:        time.Now().UTC(),
-	}
-
-	// all sign
-	for i := 0; i < len(validators); i++ {
-		vote := withValidator(voteProto, validators[i].GetAddress(), i)
-		_, err := signAddVote(validators[i], vote, voteSet)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return voteSet.MakeCommit(), nil
-}
--- a/types/genesis_test.go
+++ b/types/genesis_test.go
@@ -54,7 +54,7 @@ func TestGenesis(t *testing.T) {
 	assert.NoError(t, err, "expected no error for valid genDoc json")

 	// test with invalid consensus params
-	genDoc.ConsensusParams.BlockSizeParams.MaxBytes = 0
+	genDoc.ConsensusParams.BlockSize.MaxBytes = 0
 	genDocBytes, err = json.Marshal(genDoc)
 	assert.NoError(t, err, "error marshalling genDoc")
 	genDoc, err = GenesisDocFromJSON(genDocBytes)
--- a/types/params.go
+++ b/types/params.go
@@ -2,6 +2,9 @@ package types

 import (
 	"github.com/pkg/errors"
+
+	abci "github.com/tendermint/abci/types"
+	"github.com/tendermint/tmlibs/merkle"
 )

 const (
@@ -11,58 +14,58 @@ const (
 // ConsensusParams contains consensus critical parameters
 // that determine the validity of blocks.
 type ConsensusParams struct {
-	BlockSizeParams   `json:"block_size_params"`
-	TxSizeParams      `json:"tx_size_params"`
-	BlockGossipParams `json:"block_gossip_params"`
+	BlockSize   `json:"block_size_params"`
+	TxSize      `json:"tx_size_params"`
+	BlockGossip `json:"block_gossip_params"`
 }

-// BlockSizeParams contain limits on the block size.
-type BlockSizeParams struct {
-	MaxBytes int `json:"max_bytes"` // NOTE: must not be 0 nor greater than 100MB
-	MaxTxs   int `json:"max_txs"`
-	MaxGas   int `json:"max_gas"`
+// BlockSize contain limits on the block size.
+type BlockSize struct {
+	MaxBytes int   `json:"max_bytes"` // NOTE: must not be 0 nor greater than 100MB
+	MaxTxs   int   `json:"max_txs"`
+	MaxGas   int64 `json:"max_gas"`
 }

-// TxSizeParams contain limits on the tx size.
-type TxSizeParams struct {
-	MaxBytes int `json:"max_bytes"`
-	MaxGas   int `json:"max_gas"`
+// TxSize contain limits on the tx size.
+type TxSize struct {
+	MaxBytes int   `json:"max_bytes"`
+	MaxGas   int64 `json:"max_gas"`
 }

-// BlockGossipParams determine consensus critical elements of how blocks are gossiped
-type BlockGossipParams struct {
+// BlockGossip determine consensus critical elements of how blocks are gossiped
+type BlockGossip struct {
 	BlockPartSizeBytes int `json:"block_part_size_bytes"` // NOTE: must not be 0
 }

 // DefaultConsensusParams returns a default ConsensusParams.
 func DefaultConsensusParams() *ConsensusParams {
 	return &ConsensusParams{
-		DefaultBlockSizeParams(),
-		DefaultTxSizeParams(),
-		DefaultBlockGossipParams(),
+		DefaultBlockSize(),
+		DefaultTxSize(),
+		DefaultBlockGossip(),
 	}
 }

-// DefaultBlockSizeParams returns a default BlockSizeParams.
-func DefaultBlockSizeParams() BlockSizeParams {
-	return BlockSizeParams{
+// DefaultBlockSize returns a default BlockSize.
+func DefaultBlockSize() BlockSize {
+	return BlockSize{
 		MaxBytes: 22020096, // 21MB
 		MaxTxs:   100000,
 		MaxGas:   -1,
 	}
 }

-// DefaultTxSizeParams returns a default TxSizeParams.
-func DefaultTxSizeParams() TxSizeParams {
-	return TxSizeParams{
+// DefaultTxSize returns a default TxSize.
+func DefaultTxSize() TxSize {
+	return TxSize{
 		MaxBytes: 10240, // 10kB
 		MaxGas:   -1,
 	}
 }

-// DefaultBlockGossipParams returns a default BlockGossipParams.
-func DefaultBlockGossipParams() BlockGossipParams {
-	return BlockGossipParams{
+// DefaultBlockGossip returns a default BlockGossip.
+func DefaultBlockGossip() BlockGossip {
+	return BlockGossip{
 		BlockPartSizeBytes: 65536, // 64kB,
 	}
 }
@@ -71,17 +74,69 @@ func DefaultBlockGossipParams() BlockGossipParams {
 // are within their allowed limits, and returns an error if they are not.
 func (params *ConsensusParams) Validate() error {
 	// ensure some values are greater than 0
-	if params.BlockSizeParams.MaxBytes <= 0 {
-		return errors.Errorf("BlockSizeParams.MaxBytes must be greater than 0. Got %d", params.BlockSizeParams.MaxBytes)
+	if params.BlockSize.MaxBytes <= 0 {
+		return errors.Errorf("BlockSize.MaxBytes must be greater than 0. Got %d", params.BlockSize.MaxBytes)
 	}
-	if params.BlockGossipParams.BlockPartSizeBytes <= 0 {
-		return errors.Errorf("BlockGossipParams.BlockPartSizeBytes must be greater than 0. Got %d", params.BlockGossipParams.BlockPartSizeBytes)
+	if params.BlockGossip.BlockPartSizeBytes <= 0 {
+		return errors.Errorf("BlockGossip.BlockPartSizeBytes must be greater than 0. Got %d", params.BlockGossip.BlockPartSizeBytes)
 	}

 	// ensure blocks aren't too big
-	if params.BlockSizeParams.MaxBytes > maxBlockSizeBytes {
-		return errors.Errorf("BlockSizeParams.MaxBytes is too big. %d > %d",
-			params.BlockSizeParams.MaxBytes, maxBlockSizeBytes)
+	if params.BlockSize.MaxBytes > maxBlockSizeBytes {
+		return errors.Errorf("BlockSize.MaxBytes is too big. %d > %d",
+			params.BlockSize.MaxBytes, maxBlockSizeBytes)
 	}
 	return nil
 }
+
+// Hash returns a merkle hash of the parameters to store
+// in the block header
+func (params *ConsensusParams) Hash() []byte {
+	return merkle.SimpleHashFromMap(map[string]interface{}{
+		"block_gossip_part_size_bytes": params.BlockGossip.BlockPartSizeBytes,
+		"block_size_max_bytes":         params.BlockSize.MaxBytes,
+		"block_size_max_gas":           params.BlockSize.MaxGas,
+		"block_size_max_txs":           params.BlockSize.MaxTxs,
+		"tx_size_max_bytes":            params.TxSize.MaxBytes,
+		"tx_size_max_gas":              params.TxSize.MaxGas,
+	})
+}
+
+// Update returns a copy of the params with updates from the non-zero fields of p2.
+// NOTE: note: must not modify the original
+func (params ConsensusParams) Update(params2 *abci.ConsensusParams) ConsensusParams {
+	res := params // explicit copy
+
+	if params2 == nil {
+		return res
+	}
+
+	// we must defensively consider any structs may be nil
+	// XXX: it's cast city over here. It's ok because we only do int32->int
+	// but still, watch it champ.
+	if params2.BlockSize != nil {
+		if params2.BlockSize.MaxBytes > 0 {
+			res.BlockSize.MaxBytes = int(params2.BlockSize.MaxBytes)
+		}
+		if params2.BlockSize.MaxTxs > 0 {
+			res.BlockSize.MaxTxs = int(params2.BlockSize.MaxTxs)
+		}
+		if params2.BlockSize.MaxGas > 0 {
+			res.BlockSize.MaxGas = params2.BlockSize.MaxGas
+		}
+	}
+	if params2.TxSize != nil {
+		if params2.TxSize.MaxBytes > 0 {
+			res.TxSize.MaxBytes = int(params2.TxSize.MaxBytes)
+		}
+		if params2.TxSize.MaxGas > 0 {
+			res.TxSize.MaxGas = params2.TxSize.MaxGas
+		}
+	}
+	if params2.BlockGossip != nil {
+		if params2.BlockGossip.BlockPartSizeBytes > 0 {
+			res.BlockGossip.BlockPartSizeBytes = int(params2.BlockGossip.BlockPartSizeBytes)
+		}
+	}
+	return res
+}
--- a/types/params_test.go
+++ b/types/params_test.go
@@ -1,6 +1,8 @@
 package types

 import (
+	"bytes"
+	"sort"
 	"testing"

 	"github.com/stretchr/testify/assert"
@@ -8,8 +10,8 @@ import (

 func newConsensusParams(blockSize, partSize int) ConsensusParams {
 	return ConsensusParams{
-		BlockSizeParams:   BlockSizeParams{MaxBytes: blockSize},
-		BlockGossipParams: BlockGossipParams{BlockPartSizeBytes: partSize},
+		BlockSize:   BlockSize{MaxBytes: blockSize},
+		BlockGossip: BlockGossip{BlockPartSizeBytes: partSize},
 	}
 }

@@ -38,3 +40,49 @@ func TestConsensusParamsValidation(t *testing.T) {
 		}
 	}
 }
+
+func makeParams(blockBytes, blockTx, blockGas, txBytes,
+	txGas, partSize int) ConsensusParams {
+
+	return ConsensusParams{
+		BlockSize: BlockSize{
+			MaxBytes: blockBytes,
+			MaxTxs:   blockTx,
+			MaxGas:   int64(blockGas),
+		},
+		TxSize: TxSize{
+			MaxBytes: txBytes,
+			MaxGas:   int64(txGas),
+		},
+		BlockGossip: BlockGossip{
+			BlockPartSizeBytes: partSize,
+		},
+	}
+}
+
+func TestConsensusParamsHash(t *testing.T) {
+	params := []ConsensusParams{
+		makeParams(1, 2, 3, 4, 5, 6),
+		makeParams(7, 2, 3, 4, 5, 6),
+		makeParams(1, 7, 3, 4, 5, 6),
+		makeParams(1, 2, 7, 4, 5, 6),
+		makeParams(1, 2, 3, 7, 5, 6),
+		makeParams(1, 2, 3, 4, 7, 6),
+		makeParams(1, 2, 3, 4, 5, 7),
+		makeParams(6, 5, 4, 3, 2, 1),
+	}
+
+	hashes := make([][]byte, len(params))
+	for i := range params {
+		hashes[i] = params[i].Hash()
+	}
+
+	// make sure there are no duplicates...
+	// sort, then check in order for matches
+	sort.Slice(hashes, func(i, j int) bool {
+		return bytes.Compare(hashes[i], hashes[j]) < 0
+	})
+	for i := 0; i < len(hashes)-1; i++ {
+		assert.NotEqual(t, hashes[i], hashes[i+1])
+	}
+}
--- a/types/protobuf.go
+++ b/types/protobuf.go
@@ -12,11 +12,11 @@ type tm2pb struct{}

 func (tm2pb) Header(header *Header) *types.Header {
 	return &types.Header{
-		ChainId:        header.ChainID,
+		ChainID:        header.ChainID,
 		Height:         header.Height,
 		Time:           header.Time.Unix(),
 		NumTxs:         int32(header.NumTxs), // XXX: overflow
-		LastBlockId:    TM2PB.BlockID(header.LastBlockID),
+		LastBlockID:    TM2PB.BlockID(header.LastBlockID),
 		LastCommitHash: header.LastCommitHash,
 		DataHash:       header.DataHash,
 		AppHash:        header.AppHash,
@@ -51,3 +51,21 @@ func (tm2pb) Validators(vals *ValidatorSet) []*types.Validator {
 	}
 	return validators
 }
+
+func (tm2pb) ConsensusParams(params *ConsensusParams) *types.ConsensusParams {
+	return &types.ConsensusParams{
+		BlockSize: &types.BlockSize{
+
+			MaxBytes: int32(params.BlockSize.MaxBytes),
+			MaxTxs:   int32(params.BlockSize.MaxTxs),
+			MaxGas:   params.BlockSize.MaxGas,
+		},
+		TxSize: &types.TxSize{
+			MaxBytes: int32(params.TxSize.MaxBytes),
+			MaxGas:   params.TxSize.MaxGas,
+		},
+		BlockGossip: &types.BlockGossip{
+			BlockPartSizeBytes: int32(params.BlockGossip.BlockPartSizeBytes),
+		},
+	}
+}
--- a/types/test_util.go
+++ b/types/test_util.go
@@ -0,0 +1,37 @@
+package types
+
+import "time"
+
+func MakeCommit(blockID BlockID, height int64, round int,
+	voteSet *VoteSet,
+	validators []*PrivValidatorFS) (*Commit, error) {
+
+	// all sign
+	for i := 0; i < len(validators); i++ {
+
+		vote := &Vote{
+			ValidatorAddress: validators[i].GetAddress(),
+			ValidatorIndex:   i,
+			Height:           height,
+			Round:            round,
+			Type:             VoteTypePrecommit,
+			BlockID:          blockID,
+			Timestamp:        time.Now().UTC(),
+		}
+
+		_, err := signAddVote(validators[i], vote, voteSet)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return voteSet.MakeCommit(), nil
+}
+
+func signAddVote(privVal *PrivValidatorFS, vote *Vote, voteSet *VoteSet) (signed bool, err error) {
+	vote.Signature, err = privVal.Signer.Sign(SignBytes(voteSet.ChainID(), vote))
+	if err != nil {
+		return false, err
+	}
+	return voteSet.AddVote(vote)
+}
--- a/types/vote_set_test.go
+++ b/types/vote_set_test.go
@@ -59,16 +59,6 @@ func withBlockPartsHeader(vote *Vote, blockPartsHeader PartSetHeader) *Vote {
 	return vote
 }

-func signAddVote(privVal *PrivValidatorFS, vote *Vote, voteSet *VoteSet) (bool, error) {
-	var err error
-	vote.Signature, err = privVal.Signer.Sign(SignBytes(voteSet.ChainID(), vote))
-	if err != nil {
-		return false, err
-	}
-	added, err := voteSet.AddVote(vote)
-	return added, err
-}
-
 func TestAddVote(t *testing.T) {
 	height, round := int64(1), 0
 	voteSet, _, privValidators := randVoteSet(height, round, VoteTypePrevote, 10, 1)