70 lines
1.7 KiB
Go
70 lines
1.7 KiB
Go
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package ecdsa
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import (
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rand"
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"crypto/sha256"
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"fmt"
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"math/big"
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)
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// GenPrivKey generates a new secp256r1 private key. It uses operating system randomness.
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func GenPrivKey(curve elliptic.Curve) (PrivKey, error) {
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key, err := ecdsa.GenerateKey(curve, rand.Reader)
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if err != nil {
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return PrivKey{}, err
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}
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return PrivKey{*key}, nil
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}
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type PrivKey struct {
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ecdsa.PrivateKey
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}
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// PubKey returns ECDSA public key associated with this private key.
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func (sk *PrivKey) PubKey() PubKey {
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return PubKey{sk.PublicKey, nil}
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}
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// Bytes serialize the private key using big-endian.
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func (sk *PrivKey) Bytes() []byte {
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if sk == nil {
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return nil
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}
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fieldSize := (sk.Curve.Params().BitSize + 7) / 8
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bz := make([]byte, fieldSize)
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sk.D.FillBytes(bz)
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return bz
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}
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// Sign hashes and signs the message usign ECDSA. Implements SDK PrivKey interface.
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func (sk *PrivKey) Sign(msg []byte) ([]byte, error) {
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digest := sha256.Sum256(msg)
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return sk.PrivateKey.Sign(rand.Reader, digest[:], nil)
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}
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// String returns a string representation of the public key based on the curveName.
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func (sk *PrivKey) String(name string) string {
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return name + "{-}"
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}
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// MarshalTo implements proto.Marshaler interface.
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func (sk *PrivKey) MarshalTo(dAtA []byte) (int, error) {
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bz := sk.Bytes()
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copy(dAtA, bz)
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return len(bz), nil
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}
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// Unmarshal implements proto.Marshaler interface.
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func (sk *PrivKey) Unmarshal(bz []byte, curve elliptic.Curve, expectedSize int) error {
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if len(bz) != expectedSize {
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return fmt.Errorf("wrong ECDSA SK bytes, expecting %d bytes", expectedSize)
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}
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sk.Curve = curve
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sk.D = new(big.Int).SetBytes(bz)
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sk.X, sk.Y = curve.ScalarBaseMult(bz)
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return nil
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}
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