HmacSHA256编码

1、首先引入需要的头文件

#import 
#import 

2、实现方法

// HmacSHA256
- (NSString *)HmacSHA256:(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;
}