well-goknown/vendor/github.com/btcsuite/btcd/btcec/v2/pubkey.go

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// Copyright (c) 2013-2014 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package btcec
import (
secp "github.com/decred/dcrd/dcrec/secp256k1/v4"
)
// These constants define the lengths of serialized public keys.
const (
// PubKeyBytesLenCompressed is the bytes length of a serialized compressed
// public key.
PubKeyBytesLenCompressed = 33
)
const (
pubkeyCompressed byte = 0x2 // y_bit + x coord
pubkeyUncompressed byte = 0x4 // x coord + y coord
pubkeyHybrid byte = 0x6 // y_bit + x coord + y coord
)
// IsCompressedPubKey returns true the passed serialized public key has
// been encoded in compressed format, and false otherwise.
func IsCompressedPubKey(pubKey []byte) bool {
// The public key is only compressed if it is the correct length and
// the format (first byte) is one of the compressed pubkey values.
return len(pubKey) == PubKeyBytesLenCompressed &&
(pubKey[0]&^byte(0x1) == pubkeyCompressed)
}
// ParsePubKey parses a public key for a koblitz curve from a bytestring into a
// ecdsa.Publickey, verifying that it is valid. It supports compressed,
// uncompressed and hybrid signature formats.
func ParsePubKey(pubKeyStr []byte) (*PublicKey, error) {
return secp.ParsePubKey(pubKeyStr)
}
// PublicKey is an ecdsa.PublicKey with additional functions to
// serialize in uncompressed, compressed, and hybrid formats.
type PublicKey = secp.PublicKey
// NewPublicKey instantiates a new public key with the given x and y
// coordinates.
//
// It should be noted that, unlike ParsePubKey, since this accepts arbitrary x
// and y coordinates, it allows creation of public keys that are not valid
// points on the secp256k1 curve. The IsOnCurve method of the returned instance
// can be used to determine validity.
func NewPublicKey(x, y *FieldVal) *PublicKey {
return secp.NewPublicKey(x, y)
}
// SerializedKey is a type for representing a public key in its compressed
// serialized form.
//
// NOTE: This type is useful when using public keys as keys in maps.
type SerializedKey [PubKeyBytesLenCompressed]byte
// ToPubKey returns the public key parsed from the serialized key.
func (s SerializedKey) ToPubKey() (*PublicKey, error) {
return ParsePubKey(s[:])
}
// SchnorrSerialized returns the Schnorr serialized, x-only 32-byte
// representation of the serialized key.
func (s SerializedKey) SchnorrSerialized() [32]byte {
var serializedSchnorr [32]byte
copy(serializedSchnorr[:], s[1:])
return serializedSchnorr
}
// CopyBytes returns a copy of the underlying array as a byte slice.
func (s SerializedKey) CopyBytes() []byte {
c := make([]byte, PubKeyBytesLenCompressed)
copy(c, s[:])
return c
}
// ToSerialized serializes a public key into its compressed form.
func ToSerialized(pubKey *PublicKey) SerializedKey {
var serialized SerializedKey
copy(serialized[:], pubKey.SerializeCompressed())
return serialized
}