Comparing MD5 hash on UIImage on iPhone and file on server
hash, ios, iphone, md5, php
Solution
`D41D8CD98F00B204E9800998ECF8427E` is the MD5 sum of an empty file. Your don't read the file correctly, the reason is probably that dataWithContentsOfFile: needs an absolute path. Try:
NSString *path = [[NSBundle mainBundle] pathForResource:@"advert" ofType:@"png"];
NSData *plistData = [NSData dataWithContentsOfFile:path];
Problem
I am attempting to compute a MD5 hash within an iOS app, in an effort to compare hashes between the file saved within the app and the same file stored on a web server using PHP. This is the code for the iOS app: ``` unsigned char result[CC_MD5_DIGEST_LENGTH]; NSData* data = [NSData dataWithContentsOfFile:@"advert.png"]; const void* src = [data bytes]; CC_MD5(src, [data length], result); NSString *imageHash = [[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]] lowercaseString]; NSLog(@"%@", imageHash); ``` The code for the web server: ``` $file = 'advert.png'; echo 'MD5 file hash of ' . $file . ': ' . md5_file($file); ``` The app generates: D41D8CD98F00B204E9800998ECF8427E The PHP generates: 3ef9386b1dd50e8e166efbe48f0f9401 md5sum generates: 3ef9386b1dd50e8e166efbe48f0f9401 UPDATE: Just ran the app through the simulator and it correctly computes the hash: 3ef9386b1dd50e8e166efbe48f0f9401. When ran on my iPhone 4 running iOS 5.1 it calculates as: ddf017003e063e353a5e4ec2cc4a5095