problem with applying md5 to data
problem with applying md5 to data
- Subject: problem with applying md5 to data
- From: Wilker <email@hidden>
- Date: Wed, 29 Jun 2011 04:02:05 -0300
Hi guys,
I need to generate a hash from a file, the hash algorithm is here:
http://thesubdb.com/api/
I'm trying to implement it on Objective-C but I'm having really trouble on
it...
This is my current implementation:
//
// SMSubdbSource.m
// Subtitle Master
//
// Created by Wilker Lúcio da Silva on 6/23/11.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#import "SMSubdbSource.h"
#import <CommonCrypto/CommonDigest.h>
@implementation SMSubdbSource
+(NSString *)md5:(NSString *)str {
const char *cStr = [str UTF8String];
unsigned char result[16];
CC_MD5(cStr, (unsigned int) strlen(cStr), result);
return [NSString stringWithFormat:
@"XXXXXXXXXXXXXXXX",
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]
];
}
+(NSString *)generateHashFromPath:(NSString *)path {
const NSUInteger CHUNK_SIZE = 65536;
NSFileHandle *file = [NSFileHandle fileHandleForReadingAtPath:path];
if (file == nil) return nil;
unsigned long fileSize = [[[NSFileManager defaultManager]
attributesOfItemAtPath:path error:nil] fileSize];
NSMutableData *fileData = [[NSMutableData alloc]
initWithCapacity:CHUNK_SIZE * 2];
[fileData appendData:[file readDataOfLength:CHUNK_SIZE]];
[file seekToFileOffset:MAX(0, fileSize - CHUNK_SIZE)];
[fileData appendData:[file readDataOfLength:CHUNK_SIZE]];
[file closeFile];
NSString *dataString = [[NSString alloc] initWithData:fileData
encoding:NSASCIIStringEncoding];
return [[SMSubdbSource md5:dataString] lowercaseString];
}
@end
It works well if file only contains ASCII simple chars, but the real files
(that contains video binary data) generates wrong hash... I mean the problem
should be when trying to generate the string and MD5 digest from it...
How I can make it work correctly?
---
Wilker Lúcio
http://about.me/wilkerlucio/bio
Kajabi Consultant
+55 81 82556600
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