/
sign.go
47 lines (39 loc) · 1.17 KB
/
sign.go
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package sign
import (
"crypto/ecdsa"
"crypto/rand"
"fmt"
)
type ecdsaSigner struct {
privateKey *ecdsa.PrivateKey
hasher Hasher
encoder Encoder
}
// NewECDSA is a constructor function for the ecdsaSigner type
func NewECDSA(privKey *ecdsa.PrivateKey, hasher Hasher, encoder Encoder) *ecdsaSigner {
return &ecdsaSigner{
privateKey: privKey,
hasher: hasher,
encoder: encoder,
}
}
// Sign generates a digital signature based on the provided message
func (ec *ecdsaSigner) Sign(message string) (string, error) {
hash := ec.hasher.Hash([]byte(message))
signatureBytes, err := ecdsa.SignASN1(rand.Reader, ec.privateKey, hash)
if err != nil {
return "", fmt.Errorf("ecdsa sign: %w", err)
}
signature := ec.encoder.Encode(signatureBytes)
return signature, nil
}
// Verify checks the validity of the given signature
func (ec *ecdsaSigner) Verify(signature, message string) (bool, error) {
signatureBytes, err := ec.encoder.Decode(signature)
if err != nil {
return false, fmt.Errorf("signature string decode: %w", err)
}
hash := ec.hasher.Hash([]byte(message))
valid := ecdsa.VerifyASN1(&ec.privateKey.PublicKey, hash, signatureBytes)
return valid, nil
}