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) + } +}