I'd like to use gravatar in my iPhone application. Is there anyway to generate a hexadecimal MD5 hash in Objective-C for iPhone? Using openssl on iPhone is a no-go.
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This is how I did it before I removed it from my app:
#import <CommonCrypto/CommonDigest.h> NSString* md5( NSString *str ) { const char *cStr = [str UTF8String]; unsigned char result[CC_MD5_DIGEST_LENGTH]; 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] ] lowercaseString]; }
It's only fair to add that I didn't write this myself. I found it somewhere on the internet but I didn't record where.
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The code I used for generating the necessary MD5 hash is up on my github repository, in the CommonCrypto subfolder. There are a bunch of similar routines in there which will either show you how to use CommonCrypto or how to format strings of hex byte values, base-64, etc.
A potentially better way of generating the string would be:
NSMutableString * str = [[NSMutableString alloc] initWithCapacity: 33]; int i; for ( i = 0; i < 16; i++ ) { [str appendFormat: @"%02x", result[i]]; } NSString * output = [str copy]; [str release]; return ( [output autorelease] );
If you're going to use the code in the answer above, however, I'd personally suggest changing the %02X's to %02x and forgoing the -lowercaseString call completely-- might as well generate the hex values lowercase to start with.
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