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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the go/golang LICENSE file.
package pkcs7
// These are private constants and functions from the crypto/x509 package that
// are useful when dealing with signatures verified by x509 certificates
import (
"bytes"
"crypto"
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
)
var (
oidSignatureMD2WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 2}
oidSignatureMD5WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 4}
oidSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 5}
oidSignatureSHA256WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 11}
oidSignatureSHA384WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 12}
oidSignatureSHA512WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 13}
oidSignatureRSAPSS = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 10}
oidSignatureDSAWithSHA1 = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 3}
oidSignatureDSAWithSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 3, 2}
oidSignatureECDSAWithSHA1 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 1}
oidSignatureECDSAWithSHA256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 2}
oidSignatureECDSAWithSHA384 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 3}
oidSignatureECDSAWithSHA512 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 4}
oidSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 1}
oidSHA384 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 2}
oidSHA512 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 3}
oidMGF1 = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 8}
// oidISOSignatureSHA1WithRSA means the same as oidSignatureSHA1WithRSA
// but it's specified by ISO. Microsoft's makecert.exe has been known
// to produce certificates with this OID.
oidISOSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 29}
)
var signatureAlgorithmDetails = []struct {
algo x509.SignatureAlgorithm
name string
oid asn1.ObjectIdentifier
pubKeyAlgo x509.PublicKeyAlgorithm
hash crypto.Hash
}{
{x509.MD2WithRSA, "MD2-RSA", oidSignatureMD2WithRSA, x509.RSA, crypto.Hash(0) /* no value for MD2 */},
{x509.MD5WithRSA, "MD5-RSA", oidSignatureMD5WithRSA, x509.RSA, crypto.MD5},
{x509.SHA1WithRSA, "SHA1-RSA", oidSignatureSHA1WithRSA, x509.RSA, crypto.SHA1},
{x509.SHA1WithRSA, "SHA1-RSA", oidISOSignatureSHA1WithRSA, x509.RSA, crypto.SHA1},
{x509.SHA256WithRSA, "SHA256-RSA", oidSignatureSHA256WithRSA, x509.RSA, crypto.SHA256},
{x509.SHA384WithRSA, "SHA384-RSA", oidSignatureSHA384WithRSA, x509.RSA, crypto.SHA384},
{x509.SHA512WithRSA, "SHA512-RSA", oidSignatureSHA512WithRSA, x509.RSA, crypto.SHA512},
{x509.SHA256WithRSAPSS, "SHA256-RSAPSS", oidSignatureRSAPSS, x509.RSA, crypto.SHA256},
{x509.SHA384WithRSAPSS, "SHA384-RSAPSS", oidSignatureRSAPSS, x509.RSA, crypto.SHA384},
{x509.SHA512WithRSAPSS, "SHA512-RSAPSS", oidSignatureRSAPSS, x509.RSA, crypto.SHA512},
{x509.DSAWithSHA1, "DSA-SHA1", oidSignatureDSAWithSHA1, x509.DSA, crypto.SHA1},
{x509.DSAWithSHA256, "DSA-SHA256", oidSignatureDSAWithSHA256, x509.DSA, crypto.SHA256},
{x509.ECDSAWithSHA1, "ECDSA-SHA1", oidSignatureECDSAWithSHA1, x509.ECDSA, crypto.SHA1},
{x509.ECDSAWithSHA256, "ECDSA-SHA256", oidSignatureECDSAWithSHA256, x509.ECDSA, crypto.SHA256},
{x509.ECDSAWithSHA384, "ECDSA-SHA384", oidSignatureECDSAWithSHA384, x509.ECDSA, crypto.SHA384},
{x509.ECDSAWithSHA512, "ECDSA-SHA512", oidSignatureECDSAWithSHA512, x509.ECDSA, crypto.SHA512},
}
// pssParameters reflects the parameters in an AlgorithmIdentifier that
// specifies RSA PSS. See https://tools.ietf.org/html/rfc3447#appendix-A.2.3
type pssParameters struct {
// The following three fields are not marked as
// optional because the default values specify SHA-1,
// which is no longer suitable for use in signatures.
Hash pkix.AlgorithmIdentifier `asn1:"explicit,tag:0"`
MGF pkix.AlgorithmIdentifier `asn1:"explicit,tag:1"`
SaltLength int `asn1:"explicit,tag:2"`
TrailerField int `asn1:"optional,explicit,tag:3,default:1"`
}
// asn1.NullBytes is not available prior to Go 1.9
var nullBytes = []byte{5, 0}
func getSignatureAlgorithmFromAI(ai pkix.AlgorithmIdentifier) x509.SignatureAlgorithm {
if !ai.Algorithm.Equal(oidSignatureRSAPSS) {
for _, details := range signatureAlgorithmDetails {
if ai.Algorithm.Equal(details.oid) {
return details.algo
}
}
return x509.UnknownSignatureAlgorithm
}
// RSA PSS is special because it encodes important parameters
// in the Parameters.
var params pssParameters
if _, err := asn1.Unmarshal(ai.Parameters.FullBytes, ¶ms); err != nil {
return x509.UnknownSignatureAlgorithm
}
var mgf1HashFunc pkix.AlgorithmIdentifier
if _, err := asn1.Unmarshal(params.MGF.Parameters.FullBytes, &mgf1HashFunc); err != nil {
return x509.UnknownSignatureAlgorithm
}
// PSS is greatly overburdened with options. This code forces
// them into three buckets by requiring that the MGF1 hash
// function always match the message hash function (as
// recommended in
// https://tools.ietf.org/html/rfc3447#section-8.1), that the
// salt length matches the hash length, and that the trailer
// field has the default value.
if !bytes.Equal(params.Hash.Parameters.FullBytes, nullBytes) ||
!params.MGF.Algorithm.Equal(oidMGF1) ||
!mgf1HashFunc.Algorithm.Equal(params.Hash.Algorithm) ||
!bytes.Equal(mgf1HashFunc.Parameters.FullBytes, nullBytes) ||
params.TrailerField != 1 {
return x509.UnknownSignatureAlgorithm
}
switch {
case params.Hash.Algorithm.Equal(oidSHA256) && params.SaltLength == 32:
return x509.SHA256WithRSAPSS
case params.Hash.Algorithm.Equal(oidSHA384) && params.SaltLength == 48:
return x509.SHA384WithRSAPSS
case params.Hash.Algorithm.Equal(oidSHA512) && params.SaltLength == 64:
return x509.SHA512WithRSAPSS
}
return x509.UnknownSignatureAlgorithm
}
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