mirror of
https://github.com/FiloSottile/age.git
synced 2026-01-06 12:06:20 +00:00
120 lines
2.9 KiB
Go
120 lines
2.9 KiB
Go
// Copyright 2019 Google LLC
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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package age
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import (
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"crypto/hmac"
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"crypto/rand"
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"errors"
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"fmt"
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"io"
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"github.com/FiloSottile/age/internal/format"
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"github.com/FiloSottile/age/internal/stream"
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)
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type Identity interface {
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Type() string
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Unwrap(block *format.Recipient) (fileKey []byte, err error)
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}
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type Recipient interface {
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Type() string
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Wrap(fileKey []byte) (*format.Recipient, error)
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}
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func Encrypt(dst io.Writer, recipients ...Recipient) (io.WriteCloser, error) {
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if len(recipients) == 0 {
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return nil, errors.New("no recipients specified")
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}
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fileKey := make([]byte, 16)
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if _, err := rand.Read(fileKey); err != nil {
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return nil, err
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}
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hdr := &format.Header{}
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for i, r := range recipients {
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if r.Type() == "scrypt" && len(recipients) != 1 {
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return nil, errors.New("an scrypt recipient must be the only one")
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}
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block, err := r.Wrap(fileKey)
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if err != nil {
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return nil, fmt.Errorf("failed to wrap key for recipient #%d: %v", i, err)
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}
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hdr.Recipients = append(hdr.Recipients, block)
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}
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if mac, err := headerMAC(fileKey, hdr); err != nil {
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return nil, fmt.Errorf("failed to compute header MAC: %v", err)
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} else {
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hdr.MAC = mac
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}
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if err := hdr.Marshal(dst); err != nil {
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return nil, fmt.Errorf("failed to write header: %v", err)
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}
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nonce := make([]byte, 16)
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if _, err := rand.Read(nonce); err != nil {
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return nil, err
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}
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if _, err := dst.Write(nonce); err != nil {
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return nil, fmt.Errorf("failed to write nonce: %v", err)
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}
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return stream.NewWriter(streamKey(fileKey, nonce), dst)
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}
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func Decrypt(src io.Reader, identities ...Identity) (io.Reader, error) {
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if len(identities) == 0 {
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return nil, errors.New("no identities specified")
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}
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hdr, payload, err := format.Parse(src)
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if err != nil {
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return nil, fmt.Errorf("failed to read header: %v", err)
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}
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if len(hdr.Recipients) > 20 {
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return nil, errors.New("too many recipients")
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}
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var fileKey []byte
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RecipientsLoop:
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for _, r := range hdr.Recipients {
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if r.Type == "scrypt" && len(hdr.Recipients) != 1 {
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return nil, errors.New("an scrypt recipient must be the only one")
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}
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for _, i := range identities {
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if i.Type() != r.Type {
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continue
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}
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fileKey, err = i.Unwrap(r)
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if err == nil {
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break RecipientsLoop
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}
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}
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}
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if fileKey == nil {
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return nil, errors.New("no identity matched a recipient")
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}
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if mac, err := headerMAC(fileKey, hdr); err != nil {
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return nil, fmt.Errorf("failed to compute header MAC: %v", err)
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} else if !hmac.Equal(mac, hdr.MAC) {
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return nil, errors.New("bad header MAC")
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}
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nonce := make([]byte, 16)
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if _, err := io.ReadFull(payload, nonce); err != nil {
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return nil, fmt.Errorf("failed to read nonce: %v", err)
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}
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return stream.NewReader(streamKey(fileKey, nonce), payload)
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}
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