110 行
3.6 KiB
Go
110 行
3.6 KiB
Go
// Copyright 2017 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package trs
|
|
|
|
import (
|
|
"crypto"
|
|
"crypto/ecdsa"
|
|
"crypto/rsa"
|
|
"encoding/asn1"
|
|
"errors"
|
|
"fmt"
|
|
)
|
|
|
|
// pickSignatureAlgorithm selects a signature algorithm that is compatible with
|
|
// the given public key and the list of algorithms from both sides of connection.
|
|
// The lists of signature algorithms (peerSigAlgs and ourSigAlgs) are ignored
|
|
// for tlsVersion < VersionTLS12.
|
|
//
|
|
// The returned SignatureScheme codepoint is only meaningful for TLS 1.2 and newer
|
|
// previous TLS versions have a fixed hash function.
|
|
func pickSignatureAlgorithm(pubkey crypto.PublicKey, peerSigAlgs, ourSigAlgs []SignatureScheme, tlsVersion uint16) (SignatureScheme, uint8, crypto.Hash, error) {
|
|
if tlsVersion < VersionTLS12 || len(peerSigAlgs) == 0 {
|
|
// If the client didn't specify any signature_algorithms
|
|
// extension then we can assume that it supports SHA1. See
|
|
// http://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
|
|
switch pubkey.(type) {
|
|
case *rsa.PublicKey:
|
|
if tlsVersion < VersionTLS12 {
|
|
return 0, signaturePKCS1v15, crypto.MD5SHA1, nil
|
|
} else {
|
|
return PKCS1WithSHA1, signaturePKCS1v15, crypto.SHA1, nil
|
|
}
|
|
case *ecdsa.PublicKey:
|
|
return ECDSAWithSHA1, signatureECDSA, crypto.SHA1, nil
|
|
default:
|
|
return 0, 0, 0, fmt.Errorf("tls: unsupported public key: %T", pubkey)
|
|
}
|
|
}
|
|
for _, sigAlg := range peerSigAlgs {
|
|
if !isSupportedSignatureAlgorithm(sigAlg, ourSigAlgs) {
|
|
continue
|
|
}
|
|
hashAlg, err := lookupTLSHash(sigAlg)
|
|
if err != nil {
|
|
panic("tls: supported signature algorithm has an unknown hash function")
|
|
}
|
|
sigType := signatureFromSignatureScheme(sigAlg)
|
|
if (sigType == signaturePKCS1v15 || hashAlg == crypto.SHA1) && tlsVersion >= VersionTLS13 {
|
|
// TLS 1.3 forbids RSASSA-PKCS1-v1_5 and SHA-1 for
|
|
// handshake messages.
|
|
continue
|
|
}
|
|
switch pubkey.(type) {
|
|
case *rsa.PublicKey:
|
|
if sigType == signaturePKCS1v15 || sigType == signatureRSAPSS {
|
|
return sigAlg, sigType, hashAlg, nil
|
|
}
|
|
case *ecdsa.PublicKey:
|
|
if sigType == signatureECDSA {
|
|
return sigAlg, sigType, hashAlg, nil
|
|
}
|
|
}
|
|
}
|
|
return 0, 0, 0, errors.New("tls: peer doesn't support any common signature algorithms")
|
|
}
|
|
|
|
// verifyHandshakeSignature verifies a signature against pre-hashed handshake
|
|
// contents.
|
|
func verifyHandshakeSignature(sigType uint8, pubkey crypto.PublicKey, hashFunc crypto.Hash, digest, sig []byte) error {
|
|
switch sigType {
|
|
case signatureECDSA:
|
|
pubKey, ok := pubkey.(*ecdsa.PublicKey)
|
|
if !ok {
|
|
return errors.New("tls: ECDSA signing requires a ECDSA public key")
|
|
}
|
|
ecdsaSig := new(ecdsaSignature)
|
|
if _, err := asn1.Unmarshal(sig, ecdsaSig); err != nil {
|
|
return err
|
|
}
|
|
if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
|
|
return errors.New("tls: ECDSA signature contained zero or negative values")
|
|
}
|
|
if !ecdsa.Verify(pubKey, digest, ecdsaSig.R, ecdsaSig.S) {
|
|
return errors.New("tls: ECDSA verification failure")
|
|
}
|
|
case signaturePKCS1v15:
|
|
pubKey, ok := pubkey.(*rsa.PublicKey)
|
|
if !ok {
|
|
return errors.New("tls: RSA signing requires a RSA public key")
|
|
}
|
|
if err := rsa.VerifyPKCS1v15(pubKey, hashFunc, digest, sig); err != nil {
|
|
return err
|
|
}
|
|
case signatureRSAPSS:
|
|
pubKey, ok := pubkey.(*rsa.PublicKey)
|
|
if !ok {
|
|
return errors.New("tls: RSA signing requires a RSA public key")
|
|
}
|
|
signOpts := &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash}
|
|
if err := rsa.VerifyPSS(pubKey, hashFunc, digest, sig, signOpts); err != nil {
|
|
return err
|
|
}
|
|
default:
|
|
return errors.New("tls: unknown signature algorithm")
|
|
}
|
|
return nil
|
|
}
|