/
encoders.go
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/
encoders.go
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package merkletree2
import (
"crypto/hmac"
cryptorand "crypto/rand"
"crypto/sha512"
"hash"
"github.com/keybase/go-codec/codec"
)
type EncodingType uint8
const (
// For KeyValuePairs, the hash of the pair (k, v) is p(p(k, s), v )) where p
// = HMAC-SHA512-256 and s is a secret unique per Merkle seqno. Note that
// users learn k, v and p(k,s) but not s itself, so the hash is a commitment
// to the value only and not the key. However, the key is written and hashed
// as part of the merkle tree leaf node, so keybase cannot equivocate that.
// For generic data structures, this encoder uses SHA512-256 to hash the
// msgpack canonical encoding.
EncodingTypeBlindedSHA512_256v1 EncodingType = 1
// Generic testing encoding.
EncodingTypeForTesting EncodingType = 127
)
func (e EncodingType) GetEncoder() Encoder {
switch e {
case EncodingTypeBlindedSHA512_256v1:
return NewBlindedSHA512_256v1Encoder()
default:
panic("Invalid EncodingType")
}
}
// This function returns an encoder which is potentially unsafe for concurrent
// use.
func (e EncodingType) GetUnsafeEncoder() Encoder {
switch e {
case EncodingTypeBlindedSHA512_256v1:
return NewUnsafeBlindedSHA512_256v1Encoder()
default:
panic("Invalid EncodingType")
}
}
// UnsafeBlindedSHA512_256v1Encoder is analogous to BlindedSHA512_256v1Encoder,
// but sometimes faster and not safe for concurrent use.
type UnsafeBlindedSHA512_256v1Encoder struct {
BlindedSHA512_256v1Inner
enc *codec.Encoder
dec *codec.Decoder
sha hash.Hash
encBuf []byte
}
var _ Encoder = (*UnsafeBlindedSHA512_256v1Encoder)(nil)
func NewUnsafeBlindedSHA512_256v1Encoder() *UnsafeBlindedSHA512_256v1Encoder {
var mh codec.MsgpackHandle
mh.WriteExt = true
mh.Canonical = true
return &UnsafeBlindedSHA512_256v1Encoder{enc: codec.NewEncoderBytes(nil, &mh), dec: codec.NewDecoderBytes(nil, &mh), sha: sha512.New512_256()}
}
func (e *UnsafeBlindedSHA512_256v1Encoder) EncodeTo(o interface{}, out *[]byte) (err error) {
e.enc.ResetBytes(out)
return e.enc.Encode(o)
}
func (e *UnsafeBlindedSHA512_256v1Encoder) Encode(o interface{}) (out []byte, err error) {
return out, e.EncodeTo(o, &out)
}
func (e *UnsafeBlindedSHA512_256v1Encoder) Decode(dest interface{}, src []byte) error {
e.dec.ResetBytes(src)
return e.dec.Decode(dest)
}
func (e *UnsafeBlindedSHA512_256v1Encoder) HashGeneric(o interface{}, ret *Hash) error {
err := e.EncodeTo(o, &e.encBuf)
if err != nil {
return err
}
e.sha.Reset()
_, _ = e.sha.Write(e.encBuf)
*ret = e.sha.Sum((*ret)[:0])
return nil
}
func (e *UnsafeBlindedSHA512_256v1Encoder) EncodeAndHashGeneric(o interface{}) ([]byte, Hash, error) {
enc, err := e.Encode(o)
if err != nil {
return nil, nil, err
}
e.sha.Reset()
// sha.Write never errors.
_, _ = e.sha.Write(enc)
return enc, e.sha.Sum(nil), nil
}
func (e *UnsafeBlindedSHA512_256v1Encoder) HashKeyValuePairWithKeySpecificSecret(kvp KeyValuePair, kss KeySpecificSecret) (Hash, error) {
err := e.EncodeTo(kvp.Value, &e.encBuf)
if err != nil {
return nil, err
}
return e.HashKeyEncodedValuePairWithKeySpecificSecret(KeyEncodedValuePair{Key: kvp.Key, Value: e.encBuf}, kss)
}
type BlindedSHA512_256v1Encoder struct {
BlindedSHA512_256v1Inner
mh codec.MsgpackHandle
}
var _ Encoder = &BlindedSHA512_256v1Encoder{}
func NewBlindedSHA512_256v1Encoder() *BlindedSHA512_256v1Encoder {
var mh codec.MsgpackHandle
mh.WriteExt = true
mh.Canonical = true
return &BlindedSHA512_256v1Encoder{mh: mh}
}
func (e *BlindedSHA512_256v1Encoder) EncodeTo(o interface{}, out *[]byte) (err error) {
return codec.NewEncoderBytes(out, &e.mh).Encode(o)
}
func (e *BlindedSHA512_256v1Encoder) Encode(o interface{}) (out []byte, err error) {
return out, e.EncodeTo(o, &out)
}
func (e *BlindedSHA512_256v1Encoder) Decode(dest interface{}, src []byte) error {
return codec.NewDecoderBytes(src, &e.mh).Decode(dest)
}
func (e *BlindedSHA512_256v1Encoder) EncodeAndHashGeneric(o interface{}) ([]byte, Hash, error) {
enc, err := e.Encode(o)
if err != nil {
return nil, nil, err
}
hasher := sha512.New512_256()
// hasher.Write never errors.
_, _ = hasher.Write(enc)
return enc, hasher.Sum(nil), nil
}
func (e *BlindedSHA512_256v1Encoder) HashGeneric(o interface{}, ret *Hash) error {
enc, err := e.Encode(o)
if err != nil {
return err
}
hasher := sha512.New512_256()
// hasher.Write never errors.
_, _ = hasher.Write(enc)
*ret = hasher.Sum((*ret)[:0])
return nil
}
func (e *BlindedSHA512_256v1Encoder) HashKeyValuePairWithKeySpecificSecret(kvp KeyValuePair, kss KeySpecificSecret) (Hash, error) {
encVal, err := e.Encode(kvp.Value)
if err != nil {
return nil, err
}
return e.HashKeyEncodedValuePairWithKeySpecificSecret(KeyEncodedValuePair{Key: kvp.Key, Value: encVal}, kss)
}
type BlindedSHA512_256v1Inner struct{}
func (e BlindedSHA512_256v1Inner) HashKeyEncodedValuePairWithKeySpecificSecret(kevp KeyEncodedValuePair, kss KeySpecificSecret) (h Hash, err error) {
return h, e.HashKeyEncodedValuePairWithKeySpecificSecretTo(kevp, kss, &h)
}
func (e BlindedSHA512_256v1Inner) HashKeyEncodedValuePairWithKeySpecificSecretTo(kevp KeyEncodedValuePair, kss KeySpecificSecret, ret *Hash) error {
hasher := hmac.New(sha512.New512_256, kss)
// hasher.Write never errors.
_, _ = hasher.Write(kevp.Value)
*ret = hasher.Sum((*ret)[:0])
return nil
}
func (e BlindedSHA512_256v1Inner) GenerateMasterSecret(Seqno) (MasterSecret, error) {
secret := make([]byte, 32)
_, err := cryptorand.Read(secret)
return MasterSecret(secret), err
}
func (e BlindedSHA512_256v1Inner) ComputeKeySpecificSecret(ms MasterSecret, k Key) (kss KeySpecificSecret) {
e.ComputeKeySpecificSecretTo(ms, k, &kss)
return kss
}
func (e BlindedSHA512_256v1Inner) ComputeKeySpecificSecretTo(ms MasterSecret, k Key, ret *KeySpecificSecret) {
hasher := hmac.New(sha512.New512_256, ms)
// hasher.Write never errors.
_, _ = hasher.Write(k)
*ret = hasher.Sum((*ret)[:0])
}
func (e BlindedSHA512_256v1Inner) GetEncodingType() EncodingType {
return EncodingTypeBlindedSHA512_256v1
}