minio/vendor/github.com/joyent/triton-go/authentication/ecdsa_signature.go

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//
// Copyright (c) 2018, Joyent, Inc. All rights reserved.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
package authentication
import (
"encoding/asn1"
"encoding/base64"
"fmt"
"math/big"
"github.com/pkg/errors"
"golang.org/x/crypto/ssh"
)
type ecdsaSignature struct {
hashAlgorithm string
R *big.Int
S *big.Int
}
func (s *ecdsaSignature) SignatureType() string {
return fmt.Sprintf("ecdsa-%s", s.hashAlgorithm)
}
func (s *ecdsaSignature) String() string {
toEncode := struct {
R *big.Int
S *big.Int
}{
R: s.R,
S: s.S,
}
signatureBytes, err := asn1.Marshal(toEncode)
if err != nil {
panic(fmt.Sprintf("Error marshaling signature: %s", err))
}
return base64.StdEncoding.EncodeToString(signatureBytes)
}
func newECDSASignature(signatureBlob []byte) (*ecdsaSignature, error) {
var ecSig struct {
R *big.Int
S *big.Int
}
if err := ssh.Unmarshal(signatureBlob, &ecSig); err != nil {
return nil, errors.Wrap(err, "unable to unmarshall signature")
}
rValue := ecSig.R.Bytes()
var hashAlgorithm string
switch len(rValue) {
case 31, 32:
hashAlgorithm = "sha256"
case 65, 66:
hashAlgorithm = "sha512"
default:
return nil, fmt.Errorf("Unsupported key length: %d", len(rValue))
}
return &ecdsaSignature{
hashAlgorithm: hashAlgorithm,
R: ecSig.R,
S: ecSig.S,
}, nil
}