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|
package keys
import (
"bytes"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/sha256"
"crypto/x509"
"encoding/json"
"encoding/pem"
"errors"
"fmt"
"io"
"github.com/theupdateframework/go-tuf/data"
)
func init() {
// Note: we use LoadOrStore here to prevent accidentally overriding the
// an explicit deprecated ECDSA verifier.
// TODO: When deprecated ECDSA is removed, this can switch back to Store.
VerifierMap.LoadOrStore(data.KeyTypeECDSA_SHA2_P256_OLD_FMT, NewEcdsaVerifier)
VerifierMap.LoadOrStore(data.KeyTypeECDSA_SHA2_P256, NewEcdsaVerifier)
SignerMap.Store(data.KeyTypeECDSA_SHA2_P256_OLD_FMT, newEcdsaSigner)
SignerMap.Store(data.KeyTypeECDSA_SHA2_P256, newEcdsaSigner)
}
func NewEcdsaVerifier() Verifier {
return &EcdsaVerifier{}
}
func newEcdsaSigner() Signer {
return &ecdsaSigner{}
}
type EcdsaVerifier struct {
PublicKey *PKIXPublicKey `json:"public"`
ecdsaKey *ecdsa.PublicKey
key *data.PublicKey
}
func (p *EcdsaVerifier) Public() string {
// This is already verified to succeed when unmarshalling a public key.
r, err := x509.MarshalPKIXPublicKey(p.ecdsaKey)
if err != nil {
// TODO: Gracefully handle these errors.
// See https://github.com/theupdateframework/go-tuf/issues/363
panic(err)
}
return string(r)
}
func (p *EcdsaVerifier) Verify(msg, sigBytes []byte) error {
hash := sha256.Sum256(msg)
if !ecdsa.VerifyASN1(p.ecdsaKey, hash[:], sigBytes) {
return errors.New("tuf: ecdsa signature verification failed")
}
return nil
}
func (p *EcdsaVerifier) MarshalPublicKey() *data.PublicKey {
return p.key
}
func (p *EcdsaVerifier) UnmarshalPublicKey(key *data.PublicKey) error {
// Prepare decoder limited to 512Kb
dec := json.NewDecoder(io.LimitReader(bytes.NewReader(key.Value), MaxJSONKeySize))
// Unmarshal key value
if err := dec.Decode(p); err != nil {
if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
return fmt.Errorf("tuf: the public key is truncated or too large: %w", err)
}
return err
}
ecdsaKey, ok := p.PublicKey.PublicKey.(*ecdsa.PublicKey)
if !ok {
return fmt.Errorf("invalid public key")
}
if _, err := x509.MarshalPKIXPublicKey(ecdsaKey); err != nil {
return fmt.Errorf("marshalling to PKIX key: invalid public key")
}
p.ecdsaKey = ecdsaKey
p.key = key
return nil
}
type ecdsaSigner struct {
*ecdsa.PrivateKey
}
type ecdsaPrivateKeyValue struct {
Private string `json:"private"`
Public *PKIXPublicKey `json:"public"`
}
func (s *ecdsaSigner) PublicData() *data.PublicKey {
// This uses a trusted public key JSON format with a trusted Public value.
keyValBytes, _ := json.Marshal(EcdsaVerifier{PublicKey: &PKIXPublicKey{PublicKey: s.Public()}})
return &data.PublicKey{
Type: data.KeyTypeECDSA_SHA2_P256,
Scheme: data.KeySchemeECDSA_SHA2_P256,
Algorithms: data.HashAlgorithms,
Value: keyValBytes,
}
}
func (s *ecdsaSigner) SignMessage(message []byte) ([]byte, error) {
hash := sha256.Sum256(message)
return ecdsa.SignASN1(rand.Reader, s.PrivateKey, hash[:])
}
func (s *ecdsaSigner) MarshalPrivateKey() (*data.PrivateKey, error) {
priv, err := x509.MarshalECPrivateKey(s.PrivateKey)
if err != nil {
return nil, err
}
pemKey := pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: priv})
val, err := json.Marshal(ecdsaPrivateKeyValue{
Private: string(pemKey),
Public: &PKIXPublicKey{PublicKey: s.Public()},
})
if err != nil {
return nil, err
}
return &data.PrivateKey{
Type: data.KeyTypeECDSA_SHA2_P256,
Scheme: data.KeySchemeECDSA_SHA2_P256,
Algorithms: data.HashAlgorithms,
Value: val,
}, nil
}
func (s *ecdsaSigner) UnmarshalPrivateKey(key *data.PrivateKey) error {
val := ecdsaPrivateKeyValue{}
if err := json.Unmarshal(key.Value, &val); err != nil {
return err
}
block, _ := pem.Decode([]byte(val.Private))
if block == nil {
return errors.New("invalid PEM value")
}
if block.Type != "EC PRIVATE KEY" {
return fmt.Errorf("invalid block type: %s", block.Type)
}
k, err := x509.ParseECPrivateKey(block.Bytes)
if err != nil {
return err
}
if k.Curve != elliptic.P256() {
return errors.New("unsupported ecdsa curve")
}
if _, err := json.Marshal(EcdsaVerifier{
PublicKey: &PKIXPublicKey{PublicKey: k.Public()}}); err != nil {
return fmt.Errorf("invalid public key: %s", err)
}
s.PrivateKey = k
return nil
}
func GenerateEcdsaKey() (*ecdsaSigner, error) {
privkey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return nil, err
}
return &ecdsaSigner{privkey}, nil
}
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