114 lines
2.8 KiB
Go
114 lines
2.8 KiB
Go
package signature
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import (
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"crypto/ecdsa"
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"crypto/elliptic"
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"errors"
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)
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type DataSource interface {
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ReadSignedData([]byte) ([]byte, error)
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SignedDataSize() int
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}
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type DataWithSignature interface {
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DataSource
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GetSignatureWithKey() (key, sig []byte)
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SetSignatureWithKey(key, sig []byte)
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}
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type SignOption func(*cfg)
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type KeySignatureHandler func(key []byte, sig []byte)
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type KeySignatureSource func() (key, sig []byte)
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const (
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// PrivateKeyCompressedSize is constant with compressed size of private key (SK).
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// D coordinate stored, recover PK by formula x, y = curve.ScalarBaseMul(d,bytes).
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PrivateKeyCompressedSize = 32
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// PublicKeyCompressedSize is constant with compressed size of public key (PK).
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PublicKeyCompressedSize = 33
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// PublicKeyUncompressedSize is constant with uncompressed size of public key (PK).
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// First byte always should be 0x4 other 64 bytes is X and Y (32 bytes per coordinate).
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// 2 * 32 + 1.
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PublicKeyUncompressedSize = 65
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)
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var (
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// ErrEmptyPrivateKey is returned when used private key is empty.
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ErrEmptyPrivateKey = errors.New("empty private key")
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// ErrInvalidPublicKey is returned when public key cannot be unmarshalled.
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ErrInvalidPublicKey = errors.New("invalid public key")
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// ErrInvalidSignature is returned if signature cannot be verified.
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ErrInvalidSignature = errors.New("invalid signature")
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)
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func DataSignature(key *ecdsa.PrivateKey, src DataSource, opts ...SignOption) ([]byte, error) {
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if key == nil {
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return nil, ErrEmptyPrivateKey
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}
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data, err := dataForSignature(src)
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if err != nil {
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return nil, err
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}
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defer bytesPool.Put(&data)
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cfg := defaultCfg()
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for i := range opts {
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opts[i](cfg)
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}
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return cfg.signFunc(key, data)
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}
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func SignDataWithHandler(key *ecdsa.PrivateKey, src DataSource, handler KeySignatureHandler, opts ...SignOption) error {
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sig, err := DataSignature(key, src, opts...)
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if err != nil {
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return err
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}
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b := elliptic.MarshalCompressed(key.Curve, key.X, key.Y)
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handler(b, sig)
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return nil
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}
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func VerifyDataWithSource(dataSrc DataSource, sigSrc KeySignatureSource, opts ...SignOption) error {
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data, err := dataForSignature(dataSrc)
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if err != nil {
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return err
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}
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defer bytesPool.Put(&data)
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cfg := defaultCfg()
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for i := range opts {
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opts[i](cfg)
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}
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key, sig := sigSrc()
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var pub *ecdsa.PublicKey
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if len(key) != 0 {
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x, y := elliptic.UnmarshalCompressed(elliptic.P256(), key)
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if x == nil || y == nil {
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return ErrInvalidPublicKey
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}
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pub = &ecdsa.PublicKey{Curve: elliptic.P256(), X: x, Y: y}
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}
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return cfg.verifyFunc(pub, data, sig)
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}
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func SignData(key *ecdsa.PrivateKey, v DataWithSignature, opts ...SignOption) error {
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return SignDataWithHandler(key, v, v.SetSignatureWithKey, opts...)
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}
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func VerifyData(src DataWithSignature, opts ...SignOption) error {
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return VerifyDataWithSource(src, src.GetSignatureWithKey, opts...)
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}
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