frostfs-sdk-go/crypto/ecdsa/public.go

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package frostfsecdsa
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/sha256"
"crypto/sha512"
"fmt"
"math/big"
"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
)
// PublicKey is a wrapper over ecdsa.PublicKey used for FrostFS needs.
// Provides frostfscrypto.PublicKey interface.
//
// Instances MUST be initialized from ecdsa.PublicKey using type conversion.
type PublicKey ecdsa.PublicKey
// MaxEncodedSize returns size of the compressed ECDSA public key.
func (x PublicKey) MaxEncodedSize() int {
return 33
}
// Encode encodes ECDSA public key in compressed form into buf.
// Uses exactly MaxEncodedSize bytes of the buf.
//
// Encode panics if buf length is less than MaxEncodedSize.
//
// See also Decode.
func (x PublicKey) Encode(buf []byte) int {
if len(buf) < 33 {
panic(fmt.Sprintf("too short buffer %d", len(buf)))
}
return copy(buf, (*keys.PublicKey)(&x).Bytes())
}
// Decode decodes compressed binary representation of the PublicKey.
//
// See also Encode.
func (x *PublicKey) Decode(data []byte) error {
pub, err := keys.NewPublicKeyFromBytes(data, elliptic.P256())
if err != nil {
return err
}
*x = (PublicKey)(*pub)
return nil
}
// similar to elliptic.Unmarshal but without IsOnCurve check.
func unmarshalXY(data []byte) (x *big.Int, y *big.Int) {
if len(data) != 65 {
return
} else if data[0] != 4 { // uncompressed form
return
}
p := elliptic.P256().Params().P
x = new(big.Int).SetBytes(data[1:33])
y = new(big.Int).SetBytes(data[33:])
if x.Cmp(p) >= 0 || y.Cmp(p) >= 0 {
x, y = nil, nil
}
return
}
// Verify verifies data signature calculated by ECDSA algorithm with SHA-512 hashing.
func (x PublicKey) Verify(data, signature []byte) bool {
h := sha512.Sum512(data)
r, s := unmarshalXY(signature)
return r != nil && s != nil && ecdsa.Verify((*ecdsa.PublicKey)(&x), h[:], r, s)
}
// PublicKeyRFC6979 is a wrapper over ecdsa.PublicKey used for FrostFS needs.
// Provides frostfscrypto.PublicKey interface.
//
// Instances MUST be initialized from ecdsa.PublicKey using type conversion.
type PublicKeyRFC6979 ecdsa.PublicKey
// MaxEncodedSize returns size of the compressed ECDSA public key.
func (x PublicKeyRFC6979) MaxEncodedSize() int {
return 33
}
// Encode encodes ECDSA public key in compressed form into buf.
// Uses exactly MaxEncodedSize bytes of the buf.
//
// Encode panics if buf length is less than MaxEncodedSize.
//
// See also Decode.
func (x PublicKeyRFC6979) Encode(buf []byte) int {
if len(buf) < 33 {
panic(fmt.Sprintf("too short buffer %d", len(buf)))
}
return copy(buf, (*keys.PublicKey)(&x).Bytes())
}
// Decode decodes binary representation of the ECDSA public key.
//
// See also Encode.
func (x *PublicKeyRFC6979) Decode(data []byte) error {
pub, err := keys.NewPublicKeyFromBytes(data, elliptic.P256())
if err != nil {
return err
}
*x = (PublicKeyRFC6979)(*pub)
return nil
}
// Verify verifies data signature calculated by deterministic ECDSA algorithm
// with SHA-256 hashing.
//
// See also RFC 6979.
func (x PublicKeyRFC6979) Verify(data, signature []byte) bool {
h := sha256.Sum256(data)
return (*keys.PublicKey)(&x).Verify(signature, h[:])
}