如何在 Cocoa 中创建字符串的 MD5 哈希? [英] How do I create an MD5 Hash of a string in Cocoa?

问题描述

我知道 SHA-1 是首选，但这个项目需要我使用 MD5.

I know SHA-1 is preferred, but this project requires I use MD5.

#include <openssl/md5.h>

- (NSString*) MD5Hasher: (NSString*) query {
    NSData* hashed = [query dataUsingEncoding:NSUTF8StringEncoding];
    unsigned char *digest = MD5([hashed bytes], [hashed length], NULL);
    NSString *final = [NSString stringWithUTF8String: (char *)digest];
    return final;
}

我从 StackOverflow 上另一个类似问题的答案中得到了这段代码，但是当程序在 return final;

I got this code from an answer to another similar question on StackOverflow, but I get the following error from GDB when the program breaks at return final;

(gdb) p digest
$1 = (unsigned char *) 0xa06310e4 "206b260/336316^21a/9310225204"
(gdb) po final
Cannot access memory at address 0x0
(gdb) po digest

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0xb0623630
0x98531ed7 in objc_msgSend ()
The program being debugged was signaled while in a function called from GDB.
GDB has restored the context to what it was before the call.
To change this behavior use "set unwindonsignal off"
Evaluation of the expression containing the function
(_NSPrintForDebugger) will be abandoned.

我无法理解.

推荐答案

这是我使用的类别:

NSString+MD5.h

@interface NSString (MD5)

- (NSString *)MD5String;

@end

NSString+MD5.m

#import <CommonCrypto/CommonDigest.h>

@implementation NSString (MD5)

- (NSString *)MD5String {
    const char *cStr = [self UTF8String];
    unsigned char result[CC_MD5_DIGEST_LENGTH];
    CC_MD5( cStr, (CC_LONG)strlen(cStr), result );

    return [NSString stringWithFormat:
        @"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
        result[0], result[1], result[2], result[3], 
        result[4], result[5], result[6], result[7],
        result[8], result[9], result[10], result[11],
        result[12], result[13], result[14], result[15]
    ];  
}

@end

使用

NSString *myString = @"test";
NSString *md5 = [myString MD5String]; // returns NSString of the MD5 of test

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