HmacSHA1 算法

“HMAC是密钥相关的哈希运算消息认证码（Hash-based Message Authentication Code）,HMAC运算利用哈希算法，以一个密钥和一个消息为输入，生成一个消息摘要作为输出。”

可以看出，HMAC是需要一个密钥的。所以，HMAC_SHA1也是需要一个密钥的，而SHA1不需要。

#import "AlgorithmManager.h"
#import <CommonCrypto/CommonCrypto.h>

@implementation AlgorithmManager


+ (NSString *)signWithHmacSHA1:(NSString *)input withKey:(NSString *)key{
    
    
    const char *cKey  = [key cStringUsingEncoding:NSASCIIStringEncoding];
    const char *cData = [input cStringUsingEncoding:NSASCIIStringEncoding];
    
    unsigned char cHMAC[CC_SHA1_DIGEST_LENGTH];
    
    CCHmac(kCCHmacAlgSHA1, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
    
    NSData *HMACData = [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
    
    const unsigned char *buffer = (const unsigned char *)[HMACData bytes];
    NSString *HMAC = [NSMutableString stringWithCapacity:HMACData.length * 2];
    
    for (int i = 0; i < HMACData.length; ++i)
        HMAC = [HMAC stringByAppendingFormat:@"%02lx", (unsigned long)buffer[i]];
    
    return HMAC;
    
}

@end