Can I get the modulus or exponent from a SecKeyRef object in Swift?

Question

In Swift, I created a SecKeyRef object by calling SecTrustCopyPublicKey on some raw X509 certificate data. This is what this SecKeyRef object looks like.

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Answer 1

I wrote this one base on some other's answer in stackoverflow. Currently I am using it in my production but I am happy to use another solution that doesn't require to write into keychain.

- (NSData *)getPublicKeyBitsFromKey:(SecKeyRef)givenKey host:(NSString*)host {
    NSString *tag = [NSString stringWithFormat:@"%@.%@",[[NSBundle mainBundle] bundleIdentifier], host];
    const char* publicKeyIdentifier = [tag cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *publicTag = [[NSData alloc] initWithBytes:publicKeyIdentifier length:strlen(publicKeyIdentifier) * sizeof(char)];

    OSStatus sanityCheck = noErr;
//    NSData * publicKeyBits = nil;
    CFTypeRef publicKeyBits;

    NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];

    // Set the public key query dictionary.
    [queryPublicKey setObject:(id)kSecClassKey forKey:(id)kSecClass];
    [queryPublicKey setObject:publicTag forKey:(id)kSecAttrApplicationTag];
    [queryPublicKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
    [queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnData];
    [queryPublicKey setObject:(__bridge id)givenKey forKey:(__bridge id)kSecValueRef];

    // Get the key bits.
    NSData *data = nil;
    sanityCheck = SecItemCopyMatching((CFDictionaryRef)queryPublicKey, &publicKeyBits);
    if (sanityCheck == errSecSuccess) {
        data = CFBridgingRelease(publicKeyBits);
        //I don't want to leak this information
        (void)SecItemDelete((__bridge CFDictionaryRef) queryPublicKey);
    }else {
        sanityCheck = SecItemAdd((CFDictionaryRef)queryPublicKey, &publicKeyBits);
        if (sanityCheck == errSecSuccess)
        {
            data = CFBridgingRelease(publicKeyBits);
            (void)SecItemDelete((__bridge CFDictionaryRef) queryPublicKey);
        }
    }

    return data;
}