VKO 34.10-2012 support. DigestSizeX incompatible changes

[gogost.git] / src / cypherpunks.ru / gogost / gost3410 / private.go

diff --git a/src/cypherpunks.ru/gogost/gost3410/private.go b/src/cypherpunks.ru/gogost/gost3410/private.go
index 709e61bb93d0efa713b92586e87e5636d1f7049c..d4c5c1e9e7d8015bf67c38c39d50373063ab6596 100644 (file)
--- a/src/cypherpunks.ru/gogost/gost3410/private.go
+++ b/src/cypherpunks.ru/gogost/gost3410/private.go
@@ -20,60 +20,57 @@ import (
        "errors"
        "io"
        "math/big"
-
-       "cypherpunks.ru/gogost/gost28147"
-       "cypherpunks.ru/gogost/gost341194"
 )
 
 type PrivateKey struct {
-       c   *Curve
-       ds  int
-       key *big.Int
+       c    *Curve
+       mode Mode
+       key  *big.Int
 }
 
-func NewPrivateKey(curve *Curve, ds DigestSize, raw []byte) (*PrivateKey, error) {
-       key := make([]byte, len(raw))
+func NewPrivateKey(curve *Curve, mode Mode, raw []byte) (*PrivateKey, error) {
+       if len(raw) != int(mode) {
+               errors.New("Invalid private key length")
+       }
+       key := make([]byte, int(mode))
        copy(key, raw)
        reverse(key)
        k := bytes2big(key)
        if k.Cmp(zero) == 0 {
-               return nil, errors.New("zero private key")
+               return nil, errors.New("Zero private key")
        }
-       return &PrivateKey{curve, int(ds), k}, nil
+       return &PrivateKey{curve, mode, k}, nil
 }
 
-func GenPrivateKey(curve *Curve, ds DigestSize, rand io.Reader) (*PrivateKey, error) {
-       raw := make([]byte, int(ds))
+func GenPrivateKey(curve *Curve, mode Mode, rand io.Reader) (*PrivateKey, error) {
+       raw := make([]byte, int(mode))
        if _, err := io.ReadFull(rand, raw); err != nil {
                return nil, err
        }
-       return NewPrivateKey(curve, ds, raw)
+       return NewPrivateKey(curve, mode, raw)
 }
 
-func (pk *PrivateKey) Raw() []byte {
-       raw := pad(pk.key.Bytes(), pk.ds)
+func (prv *PrivateKey) Raw() []byte {
+       raw := pad(prv.key.Bytes(), int(prv.mode))
        reverse(raw)
        return raw
 }
 
-func (pk *PrivateKey) PublicKey() (*PublicKey, error) {
-       x, y, err := pk.c.Exp(pk.key, pk.c.Bx, pk.c.By)
+func (prv *PrivateKey) PublicKey() (*PublicKey, error) {
+       x, y, err := prv.c.Exp(prv.key, prv.c.Bx, prv.c.By)
        if err != nil {
                return nil, err
        }
-       return &PublicKey{pk.c, pk.ds, x, y}, nil
+       return &PublicKey{prv.c, prv.mode, x, y}, nil
 }
 
-func (pk *PrivateKey) SignDigest(digest []byte, rand io.Reader) ([]byte, error) {
-       if len(digest) != pk.ds {
-               return nil, errors.New("Invalid input digest length")
-       }
+func (prv *PrivateKey) SignDigest(digest []byte, rand io.Reader) ([]byte, error) {
        e := bytes2big(digest)
-       e.Mod(e, pk.c.Q)
+       e.Mod(e, prv.c.Q)
        if e.Cmp(zero) == 0 {
                e = big.NewInt(1)
        }
-       kRaw := make([]byte, pk.ds)
+       kRaw := make([]byte, int(prv.mode))
        var err error
        var k *big.Int
        var r *big.Int
@@ -84,53 +81,27 @@ Retry:
                return nil, err
        }
        k = bytes2big(kRaw)
-       k.Mod(k, pk.c.Q)
+       k.Mod(k, prv.c.Q)
        if k.Cmp(zero) == 0 {
                goto Retry
        }
-       r, _, err = pk.c.Exp(k, pk.c.Bx, pk.c.By)
+       r, _, err = prv.c.Exp(k, prv.c.Bx, prv.c.By)
        if err != nil {
                return nil, err
        }
-       r.Mod(r, pk.c.Q)
+       r.Mod(r, prv.c.Q)
        if r.Cmp(zero) == 0 {
                goto Retry
        }
-       d.Mul(pk.key, r)
+       d.Mul(prv.key, r)
        k.Mul(k, e)
        s.Add(d, k)
-       s.Mod(s, pk.c.Q)
+       s.Mod(s, prv.c.Q)
        if s.Cmp(zero) == 0 {
                goto Retry
        }
-       return append(pad(s.Bytes(), pk.ds), pad(r.Bytes(), pk.ds)...), nil
-}
-
-// Make Diffie-Hellman computation. Key Encryption Key calculation.
-// UKM is user keying material, also called VKO-factor, 8-bytes long.
-// It is based on RFC 4357 VKO GOST R 34.10-2001 with little-endian hash
-// output.
-func (pk *PrivateKey) KEK(pub *PublicKey, ukm []byte) ([]byte, error) {
-       if len(ukm) != 8 {
-               return nil, errors.New("UKM must be 8 bytes long")
-       }
-       keyX, keyY, err := pk.c.Exp(pk.key, pub.x, pub.y)
-       if err != nil {
-               return nil, err
-       }
-       t := make([]byte, DigestSize2001)
-       copy(t[int(DigestSize2001)-len(ukm):], ukm)
-       keyX, keyY, err = pk.c.Exp(bytes2big(t), keyX, keyY)
-       if err != nil {
-               return nil, err
-       }
-       h := gost341194.New(&gost28147.GostR3411_94_CryptoProParamSet)
-       copy(t, pad(keyX.Bytes(), int(DigestSize2001)))
-       reverse(t)
-       h.Write(t)
-       copy(t, pad(keyY.Bytes(), int(DigestSize2001)))
-       reverse(t)
-       h.Write(t)
-       t = h.Sum(t[:0])
-       return t, nil
+       return append(
+               pad(s.Bytes(), int(prv.mode)),
+               pad(r.Bytes(), int(prv.mode))...,
+       ), nil
 }