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