目标C：SHA1

问题描述

我如何SHA1字符串或目标C组数字？

How do i sha1 a string or set of numbers in Objective c?

推荐答案

CommonCrypto（苹果框架）具有用于计算SHA-1哈希值，包括一步骤的哈希函数：

CommonCrypto (an Apple framework) has functions for calculating SHA-1 hashes, including a one-step hash:

#include <CommonCrypto/CommonDigest.h>

unsigned char digest[CC_SHA1_DIGEST_LENGTH];
NSData *stringBytes = [someString dataUsingEncoding: NSUTF8StringEncoding]; /* or some other encoding */
if (CC_SHA1([stringBytes bytes], [stringBytes length], digest)) {
    /* SHA-1 hash has been calculated and stored in 'digest'. */
    ...
}

有关的一组数字，让我们假设你的意思是已知长度的int数组。对于这样的数据，它是比较容易反复构造的摘要，而不是使用一次性功能：

For a set of numbers, let us assume you mean an array of ints of known length. For such data, it is easier to iteratively construct the digest rather than use the one-shot function:

unsigned char digest[CC_SHA1_DIGEST_LENGTH];
uint32_t *someIntegers = ...;
size_t numIntegers = ...;

CC_SHA1_CTX ctx;
CC_SHA1_Init(&ctx);
{
    for (size_t i = 0; i < numIntegers; i++)
        CC_SHA1_Update(&ctx, someIntegers + i, sizeof(uint32_t));
}
CC_SHA1_Final(digest, &ctx);

/* SHA-1 hash has been calculated and stored in 'digest'. */
...

请注意，这并不需要字节顺序考虑。该SHA-1配备PowerPC的系统上本code计算将从i386或ARM系统上计算出的不同。解决的办法很简单 - 做计算之前交换整数已知字节序的字节数：

Note that this does not take endianness into account. The SHA-1 calculated with this code on a PowerPC system will differ from the one calculated on an i386 or ARM system. The solution is simple--swap the bytes of the integers to a known endianness before doing the calculation:

    for (size_t i = 0; i < numIntegers; i++) {
        uint32_t swapped = CFSwapInt32HostToLittle(someIntegers[i]); /* or HostToBig */
        CC_SHA1_Update(&ctx, &swapped, sizeof(swapped));
    }

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