Objective-C MD5 C Function

md5.m

#import <CommonCrypto/CommonHMAC.h>

NSString* md5(NSString *string) {
    const char *cStr = [string UTF8String];
    unsigned char digest[CC_MD5_DIGEST_LENGTH];
    CC_MD5( cStr, (unsigned int)strlen(cStr), digest );
    NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    for(int i = 0; i < CC_MD5_DIGEST_LENGTH; i++)
        [output appendFormat:@"%02x", digest[i]];
    return  output;
}