Fix exporting certificate keys on macOS 14.4. (#99981)

Apple changed the error code we get back from a failed data-key export. This caused us to not attempt to export the key using the legacy APIs and assume the key export failed. This change adds the additional error code returned from macOS 14.4.

Co-authored-by: Kevin Jones <[email protected]>

src/libraries/Common/src/Interop/OSX/System.Security.Cryptography.Native.Apple/Interop.SecKeyRef.cs

@@ -127,6 +127,10 @@ internal static bool TrySecKeyCopyExternalRepresentation(
         {
             const int errSecPassphraseRequired = -25260;
 
+            // macOS Sonoma 14.4 started returning errSecInvalidKeyAttributeMask when a key could not be exported
+            // because it must be exported with a password.
+            const int errSecInvalidKeyAttributeMask = -67738;
+
             int result = AppleCryptoNative_SecKeyCopyExternalRepresentation(
                 key,
                 out SafeCFDataHandle data,
@@ -141,7 +145,7 @@ internal static bool TrySecKeyCopyExternalRepresentation(
                         externalRepresentation = CoreFoundation.CFGetData(data);
                         return true;
                     case kErrorSeeError:
-                        if (Interop.CoreFoundation.GetErrorCode(errorHandle) == errSecPassphraseRequired)
+                        if (Interop.CoreFoundation.GetErrorCode(errorHandle) is errSecPassphraseRequired or errSecInvalidKeyAttributeMask)
                         {
                             externalRepresentation = Array.Empty<byte>();
                             return false;

src/libraries/System.Security.Cryptography.X509Certificates/tests/CertTests.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Runtime.InteropServices;
+using System.Security.Cryptography.X509Certificates.Tests.CertificateCreation;
 using System.Threading;
 using Microsoft.DotNet.XUnitExtensions;
 using Test.Cryptography;
@@ -24,6 +25,108 @@ public CertTests(ITestOutputHelper output)
             _log = output;
         }
 
+        [Fact]
+        public static void PrivateKey_FromCertificate_CanExportPrivate_ECDsa()
+        {
+            using (ECDsa ca = ECDsa.Create(ECCurve.NamedCurves.nistP256))
+            {
+                CertificateRequest req = new("CN=potatos", ca, HashAlgorithmName.SHA256);
+
+                using (X509Certificate2 cert = req.CreateSelfSigned(DateTimeOffset.Now, DateTimeOffset.Now.AddDays(3)))
+                using (ECDsa certKey = cert.GetECDsaPrivateKey())
+                {
+                    ECParameters certParameters = certKey.ExportParameters(true);
+                    ECParameters originalParameters = ca.ExportParameters(true);
+                    AssertExtensions.SequenceEqual(originalParameters.D, certParameters.D);
+                }
+            }
+        }
+
+        [Fact]
+        public static void PrivateKey_FromCertificate_CanExportPrivate_RSA()
+        {
+            using (RSA ca = RSA.Create(2048))
+            {
+                CertificateRequest req = new("CN=potatos", ca, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
+
+                using (X509Certificate2 cert = req.CreateSelfSigned(DateTimeOffset.Now, DateTimeOffset.Now.AddDays(3)))
+                using (RSA certKey = cert.GetRSAPrivateKey())
+                {
+                    RSAParameters certParameters = certKey.ExportParameters(true);
+                    RSAParameters originalParameters = ca.ExportParameters(true);
+                    AssertExtensions.SequenceEqual(originalParameters.P, certParameters.P);
+                    AssertExtensions.SequenceEqual(originalParameters.Q, certParameters.Q);
+                }
+            }
+        }
+
+        [Fact]
+        [SkipOnPlatform(PlatformSupport.MobileAppleCrypto, "DSA is not available")]
+        public static void PrivateKey_FromCertificate_CanExportPrivate_DSA()
+        {
+            DSAParameters originalParameters = TestData.GetDSA1024Params();
+
+            using (DSA ca = DSA.Create())
+            {
+                ca.ImportParameters(originalParameters);
+                DSAX509SignatureGenerator gen = new DSAX509SignatureGenerator(ca);
+                X500DistinguishedName dn = new X500DistinguishedName("CN=potatos");
+
+                CertificateRequest req = new CertificateRequest(
+                    dn,
+                    gen.PublicKey,
+                    HashAlgorithmName.SHA1);
+
+                using (X509Certificate2 cert = req.Create(dn, gen, DateTimeOffset.Now, DateTimeOffset.Now.AddDays(3), new byte[] { 1, 2, 3 }))
+                using (X509Certificate2 certWithKey = cert.CopyWithPrivateKey(ca))
+                using (DSA certKey = certWithKey.GetDSAPrivateKey())
+                {
+                    DSAParameters certParameters = certKey.ExportParameters(true);
+                    AssertExtensions.SequenceEqual(originalParameters.X, certParameters.X);
+                }
+            }
+        }
+
+        [Fact]
+        public static void PrivateKey_FromCertificate_CanExportPrivate_ECDiffieHellman()
+        {
+            using (ECDsa ca = ECDsa.Create(ECCurve.NamedCurves.nistP256))
+            using (ECDiffieHellman ecdh = ECDiffieHellman.Create(ECCurve.NamedCurves.nistP256))
+            {
+                CertificateRequest issuerRequest = new CertificateRequest(
+                    new X500DistinguishedName("CN=root"),
+                    ca,
+                    HashAlgorithmName.SHA256);
+
+                issuerRequest.CertificateExtensions.Add(
+                    new X509BasicConstraintsExtension(true, false, 0, true));
+
+                CertificateRequest request = new CertificateRequest(
+                    new X500DistinguishedName("CN=potato"),
+                    new PublicKey(ecdh),
+                    HashAlgorithmName.SHA256);
+
+                request.CertificateExtensions.Add(
+                    new X509BasicConstraintsExtension(false, false, 0, true));
+                request.CertificateExtensions.Add(
+                    new X509KeyUsageExtension(X509KeyUsageFlags.KeyAgreement, true));
+
+                DateTimeOffset notBefore = DateTimeOffset.UtcNow;
+                DateTimeOffset notAfter = notBefore.AddDays(30);
+                byte[] serial = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
+
+                using (X509Certificate2 issuer = issuerRequest.CreateSelfSigned(notBefore, notAfter))
+                using (X509Certificate2 cert = request.Create(issuer, notBefore, notAfter, serial))
+                using (X509Certificate2 certWithKey = cert.CopyWithPrivateKey(ecdh))
+                using (ECDiffieHellman certKey = certWithKey.GetECDiffieHellmanPrivateKey())
+                {
+                    ECParameters certParameters = certKey.ExportParameters(true);
+                    ECParameters originalParameters = ecdh.ExportParameters(true);
+                    AssertExtensions.SequenceEqual(originalParameters.D, certParameters.D);
+                }
+            }
+        }
+
         [Fact]
         public static void RaceUseAndDisposeDoesNotCrash()
         {
@@ -79,7 +182,7 @@ public static void X509CertTest()
                 // GetSerialNumber() returns in little-endian order.
                 Array.Reverse(expectedSerial);
                 AssertExtensions.SequenceEqual(expectedSerial, serial1);
-                
+
                 Assert.Equal("1.2.840.113549.1.1.1", cert.GetKeyAlgorithm());
 
                 int pklen = cert.GetPublicKey().Length;