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package pki
import (
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/x509"
"encoding/asn1"
"encoding/pem"
"errors"
"math/big"
)
const (
PemLabelEcdsa = "EC PRIVATE KEY"
)
type (
// This type handles the function calls to the ecdsa private key by
// implementing the interface.
EcdsaPrivateKey struct {
private_key *ecdsa.PrivateKey
}
EcdsaPublicKey struct {
public_key *ecdsa.PublicKey
}
signatureEcdsa struct {
R, S *big.Int
}
)
// generate a new ecdsa private key
func NewPrivateKeyEcdsa(curve elliptic.Curve) (*EcdsaPrivateKey, error) {
key, err := ecdsa.GenerateKey(curve, rand.Reader)
if err != nil { return nil, err }
return &EcdsaPrivateKey{key}, nil
}
// load the private key from the raw data
func LoadPrivateKeyEcdsa(raw []byte) (*EcdsaPrivateKey, error) {
key, err := x509.ParseECPrivateKey(raw)
if err != nil { return nil, err }
return &EcdsaPrivateKey{key}, nil
}
// derive a public key from the private key
func (pr EcdsaPrivateKey) Public() PublicKey {
return &EcdsaPublicKey{pr.private_key.Public().(*ecdsa.PublicKey)}
}
// sign a message with the private key
func (pr EcdsaPrivateKey) Sign(message []byte, hash crypto.Hash) ([]byte, error) {
empty := make([]byte, 0)
if !hash.Available() {
return empty, errors.New("Hash method is not available!")
}
hashed_message := hash.New()
hashed_message.Write(message)
return pr.private_key.Sign(rand.Reader, hashed_message.Sum(nil), hash)
}
// get the private key
func (pr EcdsaPrivateKey) privateKey() crypto.PrivateKey {
return pr.private_key
}
// implement Pemmer interface
func (pr EcdsaPrivateKey) MarshalPem() (marshalledPemBlock, error) {
asn1, err := x509.MarshalECPrivateKey(pr.private_key)
if err != nil { return nil, err }
pem_block := pem.Block{Type: PemLabelEcdsa, Bytes: asn1}
return pem.EncodeToMemory(&pem_block), nil
}
// marshal the public key to a pem block
func (pu *EcdsaPublicKey) MarshalPem() (marshalledPemBlock, error) {
asn1, err := x509.MarshalPKIXPublicKey(pu.public_key)
if err != nil { return nil, err }
pem_block := pem.Block{Type: PemLabelPublic, Bytes: asn1}
return pem.EncodeToMemory(&pem_block), nil
}
// verify a message using the ecdsa public key
func (pu *EcdsaPublicKey) Verify(message []byte, signature_raw []byte, hash crypto.Hash) (bool, error) {
var sig signatureEcdsa
_, err := asn1.Unmarshal(signature_raw, &sig)
if err != nil { return false, err }
hashed_message := hash.New()
hashed_message.Write(message)
return ecdsa.Verify(pu.public_key, hashed_message.Sum(nil), sig.R, sig.S), nil
}
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