NSInternalInconsistencyException when trying to create signature using SecKeyCreateSignature

The

Unexpected sessionID mismatch

exception is coming out of CryptoTokenKit. Presumably your

privateKey

value is held on a hardware token of some form, most likely the Secure Enclave (SE). What’s the lifecycle of that value? Specifically, do you keep the

SecKey

value around for long periods of time?

Our general advice for SE keys is that leave them in the keychain as much as possible, and only create a

SecKey

value when you need to operate on the key.

Regardless, the fact that you’re tripping an asset with CryptoTokenKit is definitely bugworthy. Please file a bug about this, including whatever info you have available (an Apple crash report would be especially useful). Oh, and I’d appreciate you posting your bug number, just for the record

Based on our crash log, it seems this exception happened only on some (not all) iOS 13 users (13.3.0 - 13.3.4).

Does that mean you’ve never seen it on 13.4.x?

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Hi, eskimo,

Thanks for your reply.

Yes, the eclipse curve private key is in the Secure Enclave.

I query the SecKeyRef from the keychain (at line #11) and then use it to create the signature almost immediately (call signature at line #18).

    NSDictionary *query = @{
                            (__bridge id)kSecClass: (__bridge id)kSecClassKey,
                            (__bridge id)kSecAttrKeyClass: (__bridge id)kSecAttrKeyClassPrivate,
                            (__bridge id)kSecAttrLabel: index,
                            (__bridge id)kSecReturnRef: @YES,
                            (__bridge id)kSecUseOperationPrompt: promptStr
                            };
    
        // Retrieve the key from the keychain.  
        SecKeyRef privateKey;
        OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&privateKey);
        NSData* dataToReturn = nil;
        
        if (status == errSecSuccess)
        {
            *errorCodeBack = NO_ERROR;
            dataToReturn = [self signature:inputData withKey:privateKey err:errorCodeBack];
            CFRelease(privateKey);
        }

And the NSInternalInconsistencyException happened at line #4 when calling SecKeyCreateSignature.

-(NSData*)signature:(NSData*)plainData withKey:(SecKeyRef)privateKey err:(UAF_ErrorCode*)errorCodeBack  
{  
    NSError *error;  
    NSData *signature = CFBridgingRelease(SecKeyCreateSignature(privateKey, kSecKeyAlgorithmECDSASignatureMessageX962SHA256, (CFDataRef)plainData, (void *)&error));  

    if (error) {  
        //some error handling code...  
        return nil;  
    }  
    return signature;  
} 

I query the SecKeyRef from the keychain … and then use it to create the signature almost immediately …

Oh well, so much for that theory )-:

I'll try to collect more information and file a bug about this.

Thanks. Once you’ve filed the bug, post the bug number here and I’ll take another look.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

We are experiencing same crash. FB7723269

Breakdown by device:

66% iPhone 7
11% iPhone X
7% iPhone 7
5% iPhone 7 Plus
5% iPhone 11
2% iPhone 6s
2% iPhone 11 Pro Max
2% iPhone XR

Breakdown by OS:

68% iOS 13.3.1
30% iOS 13.4.1
2% iOS 13.4.0

Stacktrace:

Fatal Exception: NSInternalInconsistencyException
0  CoreFoundation                 0x182a515f0 __exceptionPreprocess
1  libobjc.A.dylib                0x182773bcc objc_exception_throw
2  CoreFoundation                 0x1829547bc +[_CFXNotificationTokenRegistration keyCallbacks]
3  Foundation                     0x182d8bd1c -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:]
4  CryptoTokenKit                 0x1ba06205c -[TKClientTokenSession withError:accessControl:invoke:]
5  CryptoTokenKit                 0x1ba060cf0 -[TKClientTokenObject operation:data:algorithms:parameters:error:]
6  Security                       0x183868054 TKTokenCopyOperationResult
7  Security                       0x1838e02d4 __SecCTKKeyCopyOperationResult_block_invoke
8  Security                       0x1838f59b0 SecItemAuthDo
9  Security                       0x1838dfdfc SecCTKKeyCopyOperationResult
10 Security                       0x1838fe558 SecKeyRunAlgorithmAndCopyResult
11 Security                       0x1838fe41c SecKeyCreateSignature
12 Security                       0x1838fe2bc SecKeyPerformLegacyOperation
13 Security                       0x1838fe0e8 SecKeyRawSign

We are experiencing same crash. FB7723269

Thanks. And thanks for posting the bug number. Unfortunately ccyanni didn’t post theirs, so I can’t check on its status.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"