xcode ios HMAC SHA 256 hashing

Question

So I\'m trying to figure out how to do a hmacshad256 hash on ios as that\'s the hash I did for the wcf service api I made. I\'ve been trying to look for some info about it but w

Answer 1

Here is the solution I'm submitting that I put together from other answers on the matter:

This is easily adapted to other hash types by changing CC_SHA256_DIGEST_LENGTH and kCCHmacAlgSHA256.

If you're interested in doing that, check out the CommonDigest.h file within the CommonCrypto library.

#import 
#import 

+ (NSString *)hmac:(NSString *)plaintext withKey:(NSString *)key
{
    const char *cKey  = [key cStringUsingEncoding:NSASCIIStringEncoding];
    const char *cData = [plaintext cStringUsingEncoding:NSASCIIStringEncoding];
    unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
    CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
    NSData *HMACData = [NSData dataWithBytes:cHMAC length:sizeof(cHMAC)];
    const unsigned char *buffer = (const unsigned char *)[HMACData bytes];
    NSMutableString *HMAC = [NSMutableString stringWithCapacity:HMACData.length * 2];
    for (int i = 0; i < HMACData.length; ++i){
        [HMAC appendFormat:@"%02x", buffer[i]];
    }

    return HMAC;
}

This has been tested on iOS 8.x and iOS 7.x