IOS 开发中验证字符串/文件的MD5

+(NSString*) md5:(NSString*) str

{  

    const char *cStr = [str UTF8String];  

    unsigned char result[CC_MD5_DIGEST_LENGTH];  

    CC_MD5( cStr, strlen(cStr), result );  

    

    NSMutableString *hash = [NSMutableString string];

    for(int i=0;i<CC_MD5_DIGEST_LENGTH;i++)

    {

        [hash appendFormat:@"%02X",result[i]];

    }

    return [hash lowercaseString];

}

#define CHUNK_SIZE 1024  

+(NSString *)file_md5:(NSString*) path

{  

    NSFileHandle* handle = [NSFileHandle fileHandleForReadingAtPath:path];  

    if(handle == nil)  

        return nil;  

    

    CC_MD5_CTX md5_ctx;  

    CC_MD5_Init(&md5_ctx);  

    

    NSData* filedata;  

    do {  

        filedata = [handle readDataOfLength:CHUNK_SIZE];  

        CC_MD5_Update(&md5_ctx, [filedata bytes], [filedata length]);  

    }  

    while([filedata length]);  

    

    unsigned char result[CC_MD5_DIGEST_LENGTH];  

    CC_MD5_Final(result, &md5_ctx);  

    

    [handle closeFile];  

    

    NSMutableString *hash = [NSMutableString string];

    for(int i=0;i<CC_MD5_DIGEST_LENGTH;i++)

    {

        [hash appendFormat:@"%02x",result[i]];

    }

    return [hash lowercaseString];

}