xcode ios HMAC SHA 256哈希

Question

所以我想弄清楚如何在ios上做一个hmacshad256哈希,因为这是我为我所做的wcf服务api做的哈希.我一直在尝试寻找有关它的一些信息,但通常最终会得到一个SHA-256哈希.

这是我唯一的参考:

需要像Java一样在Objective C中生成HMAC SHA256哈希

而且我不确定这是否是唯一的方法(导入java hmac类)

任何帮助表示赞赏.

谢谢!

Answer 1

NSString * parameters = @"string to hash"
NSString *salt = @"saltStringHere";
NSData *saltData = [salt dataUsingEncoding:NSUTF8StringEncoding];
NSData *paramData = [parameters dataUsingEncoding:NSUTF8StringEncoding];
NSMutableData* hash = [NSMutableData dataWithLength:CC_SHA256_DIGEST_LENGTH ];
CCHmac(kCCHmacAlgSHA256, saltData.bytes, saltData.length, paramData.bytes, paramData.length, hash.mutableBytes);
NSString *base64Hash = [hash base64Encoding];

并且

#import <CommonCrypto/CommonHMAC.h>

由于从iOS 7.0 base64Encoding弃用,最后一行应该是:

NSString *base64Hash = [hash base64EncodedStringWithOptions:0];

Answer 2

这是我提交的解决方案,我从其他答案中汇总了这个问题:

通过更改CC_SHA256_DIGEST_LENGTH和kCCHmacAlgSHA256,可以轻松地将其调整为其他哈希类型.

如果您对此感兴趣,请查看CommonCrypto库中的CommonDigest.h文件.

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonCrypto.h>

+ (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;
}

这已经在iOS 8.x和iOS 7.x上进行了测试