Objective-C for iPhone中的Sha256 [英] Sha256 in Objective-C for iPhone

问题描述

当我使用这段代码创建一个字符串sha256时

  unsigned char hashedChars [32]; 
 NSString * inputString; 
 inputString = [NSString stringWithFormat：@hello]; 
 NSData * inputData = [inputString dataUsingEncoding：NSUTF8StringEncoding]; 
 CC_SHA256（inputData.bytes，inputData.length，hashedChars）; 
  

它正确返回散列，但我需要插入一个像这样的字符串 \x00 \x25\x53 ，在这种情况下，函数返回空字符串的sha256，因为指定的编码不能用于转换接收器。

现在，我的问题是：如何插入此特殊字符以生成正确的哈希？谢谢

解决方案

1）获取纯文本输入的散列

   - （NSString *）sha256HashFor：（NSString *）输入
 {
 const char * str = [输入UTF8String]; 
 unsigned char result [CC_SHA256_DIGEST_LENGTH]; 
 CC_SHA256（str，strlen（str），result）; 
 
 NSMutableString * ret = [NSMutableString stringWithCapacity：CC_SHA256_DIGEST_LENGTH * 2]; 
 for（int i = 0; i< CC_SHA256_DIGEST_LENGTH; i ++）
 {
 [ret appendFormat：@％02x，result [i]]; 
} 
 return ret; 
 
 $ / code> 

2）为 NSData 作为输入

注意：我已经使用 NSData 所以代码如下

   - （NSString *）SHA256_HASH {
 // if（！self）return nil ; 
 
 unsigned char hash [CC_SHA256_DIGEST_LENGTH]; 
 if（CC_SHA256（[（NSData *）self bytes]，[（NSData *）self length]，hash））{
 NSData * sha2 = [NSData dataWithBytes：hash length：CC_SHA256_DIGEST_LENGTH]; 
 
 //描述转换为十六进制，但是将<>在它周围并且每隔4个字节就有空格
 NSString * hash = [sha2 description]; 
 hash = [hash stringByReplacingOccurrencesOfString：@withString：@]; 
 hash = [hash stringByReplacingOccurrencesOfString：@< withString：@ ]; 
 hash = [hash stringByReplacingOccurrencesOfString：@> withString：@ ]; 
 // hash现在是一个只有40char散列值的字符串
 // NSLog（@hash =％@，hash）; 
 
 //格式化SHA256指纹像
 // // 00：00：00：00：00：00：00：00：00 
 int keyLength = [hash length]; 
 NSString * formattedKey = @; 
 for（int i = 0; i< keyLength; i + = 2）{
 NSString * substr = [hash substringWithRange：NSMakeRange（i，2）]; 
 if（i！= keyLength-2）
 substr = [substr stringByAppendingString：@：]; 
 formattedKey = [formattedKey stringByAppendingString：substr]; 
} 
 
返回formattedKey; 
} 
 return nil; 
} 
  

When I use this code to create a sha256 of a string

unsigned char hashedChars[32];
NSString *inputString;
inputString = [NSString stringWithFormat:@"hello"];
NSData * inputData = [inputString dataUsingEncoding:NSUTF8StringEncoding];
CC_SHA256(inputData.bytes, inputData.length, hashedChars);

It returns the hash correctly, but I need to insert a string like this \x00\x25\x53 and in this case, the function returns a sha256 of empty string because the specified encoding cannot be used to convert the receiver.

Now, my question is:How to insert this special characters for generate a correct hash? Thanks

解决方案

Try this, it worked for me

1) To get a hash for plain text input

-(NSString*)sha256HashFor:(NSString*)input
{   
    const char* str = [input UTF8String];
    unsigned char result[CC_SHA256_DIGEST_LENGTH];
    CC_SHA256(str, strlen(str), result);

    NSMutableString *ret = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH*2];
    for(int i = 0; i<CC_SHA256_DIGEST_LENGTH; i++)
    {
        [ret appendFormat:@"%02x",result[i]];
    }
    return ret;
}

2) To get hash for NSData as input

Note:- I have used NSData category, so the code is as follow

    - (NSString *)SHA256_HASH {
    //if (!self) return nil;

    unsigned char hash[CC_SHA256_DIGEST_LENGTH];
    if ( CC_SHA256([(NSData*)self bytes], [(NSData*)self length], hash) ) {
        NSData *sha2 = [NSData dataWithBytes:hash length:CC_SHA256_DIGEST_LENGTH]; 

        // description converts to hex but puts <> around it and spaces every 4 bytes
        NSString *hash = [sha2 description];
        hash = [hash stringByReplacingOccurrencesOfString:@" " withString:@""];
        hash = [hash stringByReplacingOccurrencesOfString:@"<" withString:@""];
        hash = [hash stringByReplacingOccurrencesOfString:@">" withString:@""];
        // hash is now a string with just the 40char hash value in it
        //NSLog(@"hash = %@",hash);

        // Format SHA256 fingerprint like
        // 00:00:00:00:00:00:00:00:00
        int keyLength=[hash length];
        NSString *formattedKey = @"";
        for (int i=0; i<keyLength; i+=2) {
            NSString *substr=[hash substringWithRange:NSMakeRange(i, 2)];
            if (i!=keyLength-2) 
                substr=[substr stringByAppendingString:@":"];
            formattedKey = [formattedKey stringByAppendingString:substr];
        }

        return formattedKey;
    }
    return nil;
}

这篇关于Objective-C for iPhone中的Sha256的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！