diff --git a/src/crypto/x509/verify.go b/src/crypto/x509/verify.go
index 98778fe..71ab62a 100644
--- a/src/crypto/x509/verify.go
+++ b/src/crypto/x509/verify.go
@@ -736,6 +736,9 @@ func (c *Certificate) isValid(certType int, currentChain []*Certificate, opts *V
// list. (While this is not specified, it is common practice in order to limit
// the types of certificates a CA can issue.)
//
+// Certificates that use SHA1WithRSA and ECDSAWithSHA1 signatures are not supported,
+// and will not be used to build chains.
+//
// WARNING: this function doesn't do any revocation checking.
func (c *Certificate) Verify(opts VerifyOptions) (chains [][]*Certificate, err error) {
// Platform-specific verification needs the ASN.1 contents so
diff --git a/src/crypto/x509/x509.go b/src/crypto/x509/x509.go
index 47be77d..85720b3 100644
--- a/src/crypto/x509/x509.go
+++ b/src/crypto/x509/x509.go
@@ -184,13 +184,13 @@ const (
MD2WithRSA // Unsupported.
MD5WithRSA // Only supported for signing, not verification.
- SHA1WithRSA // Only supported for signing, not verification.
+ SHA1WithRSA // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
SHA256WithRSA
SHA384WithRSA
SHA512WithRSA
DSAWithSHA1 // Unsupported.
DSAWithSHA256 // Unsupported.
- ECDSAWithSHA1 // Only supported for signing, not verification.
+ ECDSAWithSHA1 // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
ECDSAWithSHA256
ECDSAWithSHA384
ECDSAWithSHA512
@@ -770,7 +770,7 @@ func (c *Certificate) hasSANExtension() bool {
}
// CheckSignatureFrom verifies that the signature on c is a valid signature
-// from parent.
+// from parent. SHA1WithRSA and ECDSAWithSHA1 signatures are not supported.
func (c *Certificate) CheckSignatureFrom(parent *Certificate) error {
// RFC 5280, 4.2.1.9:
// "If the basic constraints extension is not present in a version 3
@@ -792,13 +792,13 @@ func (c *Certificate) CheckSignatureFrom(parent *Certificate) error {
// TODO(agl): don't ignore the path length constraint.
- return parent.CheckSignature(c.SignatureAlgorithm, c.RawTBSCertificate, c.Signature)
+ return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificate, c.Signature, parent.PublicKey, debugAllowSHA1)
}
// CheckSignature verifies that signature is a valid signature over signed from
// c's public key.
func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) error {
- return checkSignature(algo, signed, signature, c.PublicKey)
+ return checkSignature(algo, signed, signature, c.PublicKey, true)
}
func (c *Certificate) hasNameConstraints() bool {
@@ -818,9 +818,9 @@ func signaturePublicKeyAlgoMismatchError(expectedPubKeyAlgo PublicKeyAlgorithm,
return fmt.Errorf("x509: signature algorithm specifies an %s public key, but have public key of type %T", expectedPubKeyAlgo.String(), pubKey)
}
-// CheckSignature verifies that signature is a valid signature over signed from
+// checkSignature verifies that signature is a valid signature over signed from
// a crypto.PublicKey.
-func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey crypto.PublicKey) (err error) {
+func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey crypto.PublicKey, allowSHA1 bool) (err error) {
var hashType crypto.Hash
var pubKeyAlgo PublicKeyAlgorithm
@@ -839,7 +839,7 @@ func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey
case crypto.MD5:
return InsecureAlgorithmError(algo)
case crypto.SHA1:
- if !debugAllowSHA1 {
+ if !allowSHA1 {
return InsecureAlgorithmError(algo)
}
fallthrough
@@ -1599,11 +1599,11 @@ func CreateCertificate(rand io.Reader, template, parent *Certificate, pub, priv
// Check the signature to ensure the crypto.Signer behaved correctly.
sigAlg := getSignatureAlgorithmFromAI(signatureAlgorithm)
switch sigAlg {
- case MD5WithRSA, SHA1WithRSA, ECDSAWithSHA1:
+ case MD5WithRSA:
// We skip the check if the signature algorithm is only supported for
// signing, not verification.
default:
- if err := checkSignature(sigAlg, c.Raw, signature, key.Public()); err != nil {
+ if err := checkSignature(sigAlg, c.Raw, signature, key.Public(), true); err != nil {
return nil, fmt.Errorf("x509: signature over certificate returned by signer is invalid: %w", err)
}
}
@@ -2082,7 +2082,7 @@ func parseCertificateRequest(in *certificateRequest) (*CertificateRequest, error
// CheckSignature reports whether the signature on c is valid.
func (c *CertificateRequest) CheckSignature() error {
- return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificateRequest, c.Signature, c.PublicKey)
+ return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificateRequest, c.Signature, c.PublicKey, true)
}
// RevocationList contains the fields used to create an X.509 v2 Certificate
diff --git a/src/crypto/x509/x509_test.go b/src/crypto/x509/x509_test.go
index f3e2a77..d31f70d 100644
--- a/src/crypto/x509/x509_test.go
+++ b/src/crypto/x509/x509_test.go
@@ -13,6 +13,7 @@ import (
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
+ "crypto/boring"
_ "crypto/sha256"
_ "crypto/sha512"
"crypto/x509/pkix"
@@ -2940,30 +2941,15 @@ func TestCreateCertificateBrokenSigner(t *testing.T) {
}
func TestCreateCertificateLegacy(t *testing.T) {
- ecdsaPriv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
- if err != nil {
- t.Fatalf("Failed to generate ECDSA key: %s", err)
+ sigAlg := MD5WithRSA
+ template := &Certificate{
+ SerialNumber: big.NewInt(10),
+ DNSNames: []string{"example.com"},
+ SignatureAlgorithm: sigAlg,
}
-
- for _, sigAlg := range []SignatureAlgorithm{
- MD5WithRSA, SHA1WithRSA, ECDSAWithSHA1,
- } {
- template := &Certificate{
- SerialNumber: big.NewInt(10),
- DNSNames: []string{"example.com"},
- SignatureAlgorithm: sigAlg,
- }
- var k crypto.Signer
- switch sigAlg {
- case MD5WithRSA, SHA1WithRSA:
- k = testPrivateKey
- case ECDSAWithSHA1:
- k = ecdsaPriv
- }
- _, err := CreateCertificate(rand.Reader, template, template, k.Public(), &brokenSigner{k.Public()})
- if err != nil {
- t.Fatalf("CreateCertificate failed when SignatureAlgorithm = %v: %s", sigAlg, err)
- }
+ _, err := CreateCertificate(rand.Reader, template, template, testPrivateKey.Public(), &brokenSigner{testPrivateKey.Public()})
+ if err != nil {
+ t.Fatalf("CreateCertificate failed when SignatureAlgorithm = %v: %s", sigAlg, err)
}
}
@@ -3364,3 +3350,69 @@ func TestLargeOID(t *testing.T) {
t.Fatalf("ParseCertificate to failed to parse certificate with large OID: %s", err)
}
}
+
+func TestDisableSHA1ForCertOnly(t *testing.T) {
+ if boring.Enabled() {
+ t.Skip("not supported in boring mode")
+ }
+ defer func(old bool) { debugAllowSHA1 = old }(debugAllowSHA1)
+ debugAllowSHA1 = false
+
+ tmpl := &Certificate{
+ SerialNumber: big.NewInt(1),
+ NotBefore: time.Now().Add(-time.Hour),
+ NotAfter: time.Now().Add(time.Hour),
+ SignatureAlgorithm: SHA1WithRSA,
+ BasicConstraintsValid: true,
+ IsCA: true,
+ KeyUsage: KeyUsageCertSign | KeyUsageCRLSign,
+ }
+ certDER, err := CreateCertificate(rand.Reader, tmpl, tmpl, rsaPrivateKey.Public(), rsaPrivateKey)
+ if err != nil {
+ t.Fatalf("failed to generate test cert: %s", err)
+ }
+ cert, err := ParseCertificate(certDER)
+ if err != nil {
+ t.Fatalf("failed to parse test cert: %s", err)
+ }
+
+ err = cert.CheckSignatureFrom(cert)
+ if err == nil {
+ t.Error("expected CheckSignatureFrom to fail")
+ } else if _, ok := err.(InsecureAlgorithmError); !ok {
+ t.Errorf("expected InsecureAlgorithmError error, got %T", err)
+ }
+
+ crlDER, err := CreateRevocationList(rand.Reader, &RevocationList{
+ SignatureAlgorithm: SHA1WithRSA,
+ Number: big.NewInt(1),
+ ThisUpdate: time.Now().Add(-time.Hour),
+ NextUpdate: time.Now().Add(time.Hour),
+ }, cert, rsaPrivateKey)
+ if err != nil {
+ t.Fatalf("failed to generate test CRL: %s", err)
+ }
+ // TODO(rolandshoemaker): this should be ParseRevocationList once it lands
+ crl, err := ParseCRL(crlDER)
+ if err != nil {
+ t.Fatalf("failed to parse test CRL: %s", err)
+ }
+
+ if err = cert.CheckCRLSignature(crl); err != nil {
+ t.Errorf("unexpected error: %s", err)
+ }
+
+ // This is an unrelated OCSP response, which will fail signature verification
+ // but shouldn't return a InsecureAlgorithmError, since SHA1 should be allowed
+ // for OCSP.
+ ocspTBSHex := "30819fa2160414884451ff502a695e2d88f421bad90cf2cecbea7c180f32303133303631383037323434335a30743072304a300906052b0e03021a0500041448b60d38238df8456e4ee5843ea394111802979f0414884451ff502a695e2d88f421bad90cf2cecbea7c021100f78b13b946fc9635d8ab49de9d2148218000180f32303133303631383037323434335aa011180f32303133303632323037323434335a"
+ ocspTBS, err := hex.DecodeString(ocspTBSHex)
+ if err != nil {
+ t.Fatalf("failed to decode OCSP response TBS hex: %s", err)
+ }
+
+ err = cert.CheckSignature(SHA1WithRSA, ocspTBS, nil)
+ if err != rsa.ErrVerification {
+ t.Errorf("unexpected error: %s", err)
+ }
+}