func benchmarkAEAD(b *testing.B, c cipher.AEAD) {
b.SetBytes(benchSize)
input := make([]byte, benchSize)
output := make([]byte, benchSize)
nonce := make([]byte, c.NonceSize())
counter := 0
t := time.Now()
b.ResetTimer()
for i := 0; i < b.N; i++ {
c.Seal(output[:0], nonce, input, nil)
counter += len(output)
}
ts := time.Since(t)
b.Logf("aes-gcm speed: %.2f Mbit/s", float64(counter)*8/ts.Seconds()/1024/1024)
}
func (c AesContentCipher) encrypt(cek, plaintext, aad []byte) (iv, ciphertext, tag []byte, err error) {
var aead cipher.AEAD
aead, err = c.AeadFetch(cek)
if err != nil {
if debug.Enabled {
debug.Printf("AeadFetch failed: %s", err)
}
err = fmt.Errorf("failed to fetch AEAD: %s", err)
return
}
// Seal may panic (argh!), so protect ourselves from that
defer func() {
if e := recover(); e != nil {
switch e.(type) {
case error:
err = e.(error)
case string:
err = errors.New(e.(string))
default:
err = fmt.Errorf("%s", e)
}
return
}
}()
var bs ByteSource
if c.NonceGenerator == nil {
bs, err = NewRandomKeyGenerate(aead.NonceSize()).KeyGenerate()
} else {
bs, err = c.NonceGenerator.KeyGenerate()
}
if err != nil {
return
}
iv = bs.Bytes()
combined := aead.Seal(nil, iv, plaintext, aad)
tagoffset := len(combined) - c.TagSize()
if debug.Enabled {
debug.Printf("tagsize = %d", c.TagSize())
}
tag = combined[tagoffset:]
ciphertext = make([]byte, tagoffset)
copy(ciphertext, combined[:tagoffset])
if debug.Enabled {
debug.Printf("encrypt: combined = %x (%d)\n", combined, len(combined))
debug.Printf("encrypt: ciphertext = %x (%d)\n", ciphertext, len(ciphertext))
debug.Printf("encrypt: tag = %x (%d)\n", tag, len(tag))
debug.Printf("finally ciphertext = %x\n", ciphertext)
}
return
}
// Encrypt a proto using an AEAD.
func EncryptProto(aead cipher.AEAD, msg proto.Message, additionalData []byte) string {
plaintext := MarshalProtoOrPanic(msg)
nonce := getNonce(aead.NonceSize())
// Encrypt in-place.
ciphertext := plaintext
ciphertext = aead.Seal(ciphertext[:0], nonce, plaintext, additionalData)
outBytes := MarshalProtoOrPanic(&pb.EncryptedMessage{
Nonce: nonce,
Ciphertext: ciphertext,
})
// Return base64'd, so that the output is ASCII-safe.
return base64.RawURLEncoding.EncodeToString(outBytes)
}
// encrypt is used to encrypt a value
func (b *AESGCMBarrier) encrypt(path string, term uint32, gcm cipher.AEAD, plain []byte) []byte {
// Allocate the output buffer with room for tern, version byte,
// nonce, GCM tag and the plaintext
capacity := termSize + 1 + gcm.NonceSize() + gcm.Overhead() + len(plain)
size := termSize + 1 + gcm.NonceSize()
out := make([]byte, size, capacity)
// Set the key term
binary.BigEndian.PutUint32(out[:4], term)
// Set the version byte
out[4] = b.currentAESGCMVersionByte
// Generate a random nonce
nonce := out[5 : 5+gcm.NonceSize()]
rand.Read(nonce)
// Seal the output
switch b.currentAESGCMVersionByte {
case AESGCMVersion1:
out = gcm.Seal(out, nonce, plain, nil)
case AESGCMVersion2:
out = gcm.Seal(out, nonce, plain, []byte(path))
default:
panic("Unknown AESGCM version")
}
return out
}
/*
Encrypt generates a literal of the form <b64URLmetadata>.<b64URLciphertext>.<b64URLnonce> given an AEAD cipher, a metadata string and a data
string. Only the data is encrypted - the metadata must be appropriate to expose in the clear. Each call generates a random
nonce of the length required by the cipher.
*/
func Encrypt(aeadCipher cipher.AEAD, metadata, data string) (string, error) {
var (
nonce = make([]byte, aeadCipher.NonceSize())
ciphertext []byte
b64metadata []byte
b64ciphertext []byte
b64nonce []byte
buf bytes.Buffer
err error
)
//A nonce of the length required by the AEAD is generated
_, err = rand.Read(nonce)
if err != nil {
return "", err
}
//Seal encrypts the data using the aeadCipher's key and the nonce and appends an authentication code for the metadata
ciphertext = aeadCipher.Seal(ciphertext, nonce, []byte(data), []byte(metadata))
//Base64 Encode metadata, ciphertext and nonce
b64metadata = make([]byte, base64.URLEncoding.EncodedLen(len([]byte(metadata))))
base64.URLEncoding.Encode(b64metadata, []byte(metadata))
b64ciphertext = make([]byte, base64.URLEncoding.EncodedLen(len(ciphertext)))
base64.URLEncoding.Encode(b64ciphertext, ciphertext)
b64nonce = make([]byte, base64.URLEncoding.EncodedLen(len(nonce)))
base64.URLEncoding.Encode(b64nonce, nonce)
//Compose a <b64URLmetadata>.<b64URLciphertext>.<b64URLnonce> literal
buf.Write(b64metadata)
buf.Write([]byte("."))
buf.Write(b64ciphertext)
buf.Write([]byte("."))
buf.Write(b64nonce)
//Return the AEAD literal
return string(buf.Bytes()), nil
}
// decrypt is used to decrypt a value
func (b *AESGCMBarrier) decrypt(gcm cipher.AEAD, cipher []byte) ([]byte, error) {
// Verify the epoch
if cipher[0] != 0 || cipher[1] != 0 || cipher[2] != 0 || cipher[3] != keyEpoch {
return nil, fmt.Errorf("epoch mis-match")
}
// Verify the version byte
if cipher[4] != aesgcmVersionByte {
return nil, fmt.Errorf("version bytes mis-match")
}
// Capture the parts
nonce := cipher[5 : 5+gcm.NonceSize()]
raw := cipher[5+gcm.NonceSize():]
out := make([]byte, 0, len(raw)-gcm.NonceSize())
// Attempt to open
return gcm.Open(out, nonce, raw, nil)
}
// decrypt is used to decrypt a value
func (b *AESGCMBarrier) decrypt(gcm cipher.AEAD, cipher []byte) ([]byte, error) {
// Verify the term is always just one
term := binary.BigEndian.Uint32(cipher[:4])
if term != initialKeyTerm {
return nil, fmt.Errorf("term mis-match")
}
// Verify the version byte
if cipher[4] != aesgcmVersionByte {
return nil, fmt.Errorf("version bytes mis-match")
}
// Capture the parts
nonce := cipher[5 : 5+gcm.NonceSize()]
raw := cipher[5+gcm.NonceSize():]
out := make([]byte, 0, len(raw)-gcm.NonceSize())
// Attempt to open
return gcm.Open(out, nonce, raw, nil)
}
// encrypt is used to encrypt a value
func (b *AESGCMBarrier) encrypt(term uint32, gcm cipher.AEAD, plain []byte) []byte {
// Allocate the output buffer with room for tern, version byte,
// nonce, GCM tag and the plaintext
capacity := termSize + 1 + gcm.NonceSize() + gcm.Overhead() + len(plain)
size := termSize + 1 + gcm.NonceSize()
out := make([]byte, size, capacity)
// Set the key term
binary.BigEndian.PutUint32(out[:4], term)
// Set the version byte
out[4] = aesgcmVersionByte
// Generate a random nonce
nonce := out[5 : 5+gcm.NonceSize()]
rand.Read(nonce)
// Seal the output
out = gcm.Seal(out, nonce, plain, nil)
return out
}
// encrypt is used to encrypt a value
func (b *AESGCMBarrier) encrypt(gcm cipher.AEAD, plain []byte) []byte {
// Allocate the output buffer with room for epoch, version byte,
// nonce, GCM tag and the plaintext
capacity := epochSize + 1 + gcm.NonceSize() + gcm.Overhead() + len(plain)
size := epochSize + 1 + gcm.NonceSize()
out := make([]byte, size, capacity)
// Set the epoch to 1
out[3] = keyEpoch
// Set the version byte
out[4] = aesgcmVersionByte
// Generate a random nonce
nonce := out[5 : 5+gcm.NonceSize()]
rand.Read(nonce)
// Seal the output
out = gcm.Seal(out, nonce, plain, nil)
return out
}
// decrypt is used to decrypt a value
func (b *AESGCMBarrier) decrypt(path string, gcm cipher.AEAD, cipher []byte) ([]byte, error) {
// Verify the term is always just one
term := binary.BigEndian.Uint32(cipher[:4])
if term != initialKeyTerm {
return nil, fmt.Errorf("term mis-match")
}
// Capture the parts
nonce := cipher[5 : 5+gcm.NonceSize()]
raw := cipher[5+gcm.NonceSize():]
out := make([]byte, 0, len(raw)-gcm.NonceSize())
// Verify the cipher byte and attempt to open
switch cipher[4] {
case AESGCMVersion1:
return gcm.Open(out, nonce, raw, nil)
case AESGCMVersion2:
return gcm.Open(out, nonce, raw, []byte(path))
default:
return nil, fmt.Errorf("version bytes mis-match")
}
}
func fixNonce(gcm cipher.AEAD, nonce []byte) []byte {
realNonce := make([]byte, gcm.NonceSize())
copy(realNonce, nonce)
return realNonce
}
