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的另一个类似问题的答案得到了这个代码，当程序在 return final时中断时，从GDB中获取以下错误：

(gdb) p digest
$1 = (unsigned char *) 0xa06310e4 "\0206b\260/\336\316^\021\b\a/9\310\225\204"
(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.

我不能理解。

推荐答案

这是我使用的类别：

NSString + MD5.h

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[16];
    CC_MD5(cstr, 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

strong>

Usage

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

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