iOS SHA512算法加salt，加iteration(迭代次

一、 简单的SHA512算法

// 散列函数--sha512对字符串加密
- (NSString *)sha512String {
    const char *str = self.UTF8String;
    uint8_t buffer[CC_SHA512_DIGEST_LENGTH];
    CC_SHA512(str, (CC_LONG)strlen(str), buffer);
    return [self stringFromBytes:buffer length:CC_SHA512_DIGEST_LENGTH];
}

二、使用salt的SHA512算法

@implementation NSData (CommonDigest)
- (NSData *)SHA512HashWithSalt:(NSData *)salt {
    unsigned char hash[CC_SHA512_DIGEST_LENGTH];
    CC_SHA512_CTX context;
    CC_SHA512_Init(&context);
    if ([salt length]) {
        CC_SHA512_Update(&context, [salt bytes], (CC_LONG)[salt length]);
    }
    CC_SHA512_Update(&context, [self bytes], (CC_LONG)[self length]);
    CC_SHA512_Final(hash, &context);
    return [NSData dataWithBytes:hash length:CC_SHA512_DIGEST_LENGTH];
}
@end

三、使用salt并有iteration的SHA512算法

//第一种
NSData* createSymphonySHA512MessageDigest(const char* s, const char* salt ,int iteration) {
    uint8_t digest[CC_SHA512_DIGEST_LENGTH];
    char salted[strlen(s) + strlen(salt) + 3];
    snprintf(salted, sizeof salted, "%s{%s}", s, salt);
    CC_SHA512(salted, (CC_LONG) strlen(salted), digest);
    for (int i = 1; i < iteration; i++) {
        CC_SHA512_CTX context;
        CC_SHA512_Init(&context);
        CC_SHA512_Update(&context, digest, (CC_LONG) CC_SHA512_DIGEST_LENGTH);
        CC_SHA512_Update(&context, salted, (CC_LONG)strlen(salted));
        CC_SHA512_Final(digest, &context);
    }
    return [NSData dataWithBytes:digest length:CC_SHA512_DIGEST_LENGTH];
}
//第二种
- (NSData *)hashPassword:(NSString *)password ansSalt:(NSString *)salt iteration:(NSInteger)iteration{
    NSString *passwordSalted = [NSString stringWithFormat:@"%@{%@}",password,salt];
    NSData *passwordData = [passwordSalted dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t hash[CC_SHA512_DIGEST_LENGTH];
    CC_SHA512([passwordData bytes], [passwordData length], hash);
    NSMutableData *allData = [[NSMutableData alloc] init];
    [allData appendBytes:hash length:CC_SHA512_DIGEST_LENGTH];
    for (NSInteger i = 1; i < iteration; i++) {
        [allData appendBytes:[passwordData bytes] length:[passwordData length]];
        uint8_t hashLoop[CC_SHA512_DIGEST_LENGTH];
        CC_SHA512([allData bytes], [allData length], hashLoop);
        [allData setLength:0];
        [allData appendBytes:hashLoop length:CC_SHA512_DIGEST_LENGTH];
    }
    return [NSData dataWithBytes:[allData bytes] length:[allData length]];
}

四、和java的org.apache.shiro.crypto.hash.Sha512Hash中Sha512Hash(Object source, Object salt, int hashIterations) 一样的SHA512算法

@implementation NSData (degist)
- (NSData *)SHA512HashWithSalt:(NSData *)salt iteration:(NSInteger)iteration{
    unsigned char hash[CC_SHA512_DIGEST_LENGTH];
    CC_SHA512_CTX context;
    CC_SHA512_Init(&context);
    if ([salt length]) {
        CC_SHA512_Update(&context, [salt bytes], (CC_LONG)[salt length]);
    }
    CC_SHA512_Update(&context, [self bytes], (CC_LONG)[self length]);
    CC_SHA512_Final(hash, &context);
    for (int i = 1; i < iteration; i++) {
        CC_SHA512_CTX context;
        CC_SHA512_Init(&context);
        CC_SHA512_Update(&context, hash, (CC_LONG)CC_SHA512_DIGEST_LENGTH);
        CC_SHA512_Final(hash, &context);
    }
    return [NSData dataWithBytes:hash length:CC_SHA512_DIGEST_LENGTH];
}

参考：
1、How to use WSSE in iOS with salted sha512 with more than 1 iteration
2、Symphony SHA512 Hashing in Objective C
3、Objective C SHA512 hash of two NSData