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/*
* ZLint Copyright 2024 Regents of the University of Michigan
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy
* of the License at http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package rfc
import (
"bytes"
"github.com/zmap/zcrypto/x509"
"github.com/zmap/zlint/v3/lint"
"github.com/zmap/zlint/v3/util"
"golang.org/x/crypto/cryptobyte"
cryptobyte_asn1 "golang.org/x/crypto/cryptobyte/asn1"
)
type mismatchingSigAlg struct{}
/*******************************************************************
RFC 5280: 4.1.1.2
[the Certificate signatureAlgorithm] field MUST contain the same
algorithm identifier as the signature field in the sequence
tbsCertificate
********************************************************************/
func init() {
lint.RegisterCertificateLint(&lint.CertificateLint{
LintMetadata: lint.LintMetadata{
Name: "e_cert_sig_alg_not_match_tbs_sig_alg",
Description: "Certificate signature field must match TBSCertificate signature field",
Citation: "RFC 5280, Section 4.1.1.2",
Source: lint.RFC5280,
EffectiveDate: util.RFC5280Date,
},
Lint: NewMismatchingSigAlg,
})
}
func NewMismatchingSigAlg() lint.LintInterface {
return &mismatchingSigAlg{}
}
func (l *mismatchingSigAlg) CheckApplies(_ *x509.Certificate) bool {
return true
}
func (l *mismatchingSigAlg) Execute(c *x509.Certificate) *lint.LintResult {
// parse out certificate signatureAlgorithm
input := cryptobyte.String(c.Raw)
var cert cryptobyte.String
if !input.ReadASN1(&cert, cryptobyte_asn1.SEQUENCE) {
return &lint.LintResult{Status: lint.Fatal, Details: "error reading certificate"}
}
var tbsCert cryptobyte.String
if !cert.ReadASN1(&tbsCert, cryptobyte_asn1.SEQUENCE) {
return &lint.LintResult{Status: lint.Fatal, Details: "error reading certificate.tbsCertificate"}
}
var certSigAlg cryptobyte.String
if !cert.ReadASN1(&certSigAlg, cryptobyte_asn1.SEQUENCE) {
return &lint.LintResult{Status: lint.Fatal, Details: "error reading certificate.signatureAlgorithm"}
}
// parse out tbsCertificate signature
if !tbsCert.SkipOptionalASN1(cryptobyte_asn1.Tag(0).Constructed().ContextSpecific()) {
return &lint.LintResult{Status: lint.Fatal, Details: "error reading tbsCertificate.version"}
}
if !tbsCert.SkipASN1(cryptobyte_asn1.INTEGER) {
return &lint.LintResult{Status: lint.Fatal, Details: "error reading tbsCertificate.serialNumber"}
}
var tbsSigAlg cryptobyte.String
if !tbsCert.ReadASN1(&tbsSigAlg, cryptobyte_asn1.SEQUENCE) {
return &lint.LintResult{Status: lint.Fatal, Details: "error reading tbsCertificate.signature"}
}
if !bytes.Equal(certSigAlg, tbsSigAlg) {
return &lint.LintResult{Status: lint.Error}
}
return &lint.LintResult{Status: lint.Pass}
}
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