I have a keypair stored in an iOS keychain. I'm able to get SecKeyRef objects for both the public and private keys with no problem. What I need, however, is to convert SecKeyRef for the public key to an NSData object. I've tried the code below that I found in this answer...
- (NSData *)getPublicKeyBitsFromKey:(SecKeyRef)givenKey {
static const uint8_t publicKeyIdentifier[] = "com.your.company.publickey";
NSData *publicTag = [[NSData alloc] initWithBytes:publicKeyIdentifier length:sizeof(publicKeyIdentifier)];
OSStatus sanityCheck = noErr;
NSData * publicKeyBits = nil;
NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];
[queryPublicKey setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
[queryPublicKey setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
[queryPublicKey setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
// Temporarily add key to the Keychain, return as data:
NSMutableDictionary * attributes = [queryPublicKey mutableCopy];
[attributes setObject:(__bridge id)givenKey forKey:(__bridge id)kSecValueRef];
[attributes setObject:@YES forKey:(__bridge id)kSecReturnData];
CFTypeRef result;
sanityCheck = SecItemAdd((__bridge CFDictionaryRef) attributes, &result);
if (sanityCheck == errSecSuccess) {
publicKeyBits = CFBridgingRelease(result);
// Remove from Keychain again:
(void)SecItemDelete((__bridge CFDictionaryRef) queryPublicKey);
}
return publicKeyBits;
}
...however, when I run it, I get an OSStatus value of -50, which indicates a bad parameter somewhere. However, I can't find what could be the issue. Am I missing something in my code? Or is there a better way to convert a SecKeyRef to an NSData object? Any help you can provide is GREATLY appreciated.
