amazon web services - Is there a library for iPhone to work with HMAC-SHA-1 encoding

Question

For all operation with Amazon services(S3, EC2, SimpleDB) You need to sign all resquest with HMAC-SHA-1 Signature(http://en.wikipedia.org/wiki/HMAC , http://docs.amazonwebservices.com/AWSFWS/latest/DeveloperGuide/index.html?SummaryOfAuthentication.html).

I'm working under asp.net backend and there is no problems. Problem is in the iPhone application. iPhone developer says that there is no way to use HMAC-SHA-1 encoding, and he have no rigths to implement his own algorithm. As programmer I cannot understand why there can be a problem.

So I want too know is iPhone developer right?

I've never coded for iPhone, so I don't even where to search such an information.

Answer 1

CommonCrypto does the trick.

#import <CommonCrypto/CommonHMAC.h>

then later

/*
  inputs:
  NSData *keyData;
  NSData *clearTextData
*/

uint8_t digest[CC_SHA1_DIGEST_LENGTH] = {0};

CCHmacContext hmacContext;
CCHmacInit(&hmacContext, kCCHmacAlgSHA1, keyData.bytes, keyData.length);
CCHmacUpdate(&hmacContext, clearTextData.bytes, clearTextData.length);
CCHmacFinal(&hmacContext, digest);

NSData *out = [NSData dataWithBytes:digest length:CC_SHA1_DIGEST_LENGTH];