crypto: revert to mainline Go crypto lib (#3027)

* crypto: revert to mainline Go crypto lib

We used to use a fork for a modified bcrypt so we could pass our own
randomness but this was largely unecessary, unused, and a burden.
So now we just use the mainline Go crypto lib.

* changelog

* fix tests

* version and changelog

crypto/armor/armor.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"io/ioutil"
 
-	"golang.org/x/crypto/openpgp/armor" // forked to github.com/tendermint/crypto
+	"golang.org/x/crypto/openpgp/armor"
 )
 
 func EncodeArmor(blockType string, headers map[string]string, data []byte) string {

crypto/ed25519/ed25519.go

@@ -7,7 +7,7 @@ import (
 	"io"
 
 	amino "github.com/tendermint/go-amino"
-	"golang.org/x/crypto/ed25519" // forked to github.com/tendermint/crypto
+	"golang.org/x/crypto/ed25519"
 
 	"github.com/tendermint/tendermint/crypto"
 	"github.com/tendermint/tendermint/crypto/tmhash"

crypto/hash.go

@@ -3,7 +3,7 @@ package crypto
 import (
 	"crypto/sha256"
 
-	"golang.org/x/crypto/ripemd160" // forked to github.com/tendermint/crypto
+	"golang.org/x/crypto/ripemd160"
 )
 
 func Sha256(bytes []byte) []byte {

crypto/secp256k1/secp256k1.go

@@ -9,7 +9,7 @@ import (
 
 	secp256k1 "github.com/tendermint/btcd/btcec"
 	amino "github.com/tendermint/go-amino"
-	"golang.org/x/crypto/ripemd160" // forked to github.com/tendermint/crypto
+	"golang.org/x/crypto/ripemd160"
 
 	"github.com/tendermint/tendermint/crypto"
 )

crypto/xchacha20poly1305/xchachapoly.go

@@ -8,7 +8,7 @@ import (
 	"errors"
 	"fmt"
 
-	"golang.org/x/crypto/chacha20poly1305" // forked to github.com/tendermint/crypto
+	"golang.org/x/crypto/chacha20poly1305"
 )
 
 // Implements crypto.AEAD

crypto/xsalsa20symmetric/symmetric.go

@@ -4,7 +4,7 @@ import (
 	"errors"
 	"fmt"
 
-	"golang.org/x/crypto/nacl/secretbox" // forked to github.com/tendermint/crypto
+	"golang.org/x/crypto/nacl/secretbox"
 
 	"github.com/tendermint/tendermint/crypto"
 	cmn "github.com/tendermint/tendermint/libs/common"

crypto/xsalsa20symmetric/symmetric_test.go

@@ -6,7 +6,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"golang.org/x/crypto/bcrypt" // forked to github.com/tendermint/crypto
+	"golang.org/x/crypto/bcrypt"
 
 	"github.com/tendermint/tendermint/crypto"
 )
@@ -30,9 +30,7 @@ func TestSimpleWithKDF(t *testing.T) {
 
 	plaintext := []byte("sometext")
 	secretPass := []byte("somesecret")
-	salt := []byte("somesaltsomesalt") // len 16
-	// NOTE: we use a fork of x/crypto so we can inject our own randomness for salt
-	secret, err := bcrypt.GenerateFromPassword(salt, secretPass, 12)
+	secret, err := bcrypt.GenerateFromPassword(secretPass, 12)
 	if err != nil {
 		t.Error(err)
 	}