iOS AES Cryptography note

• hex string of salt and iv(initial vector) have to be converted into bytes, of which the length will be half of the original string.
  - (NSData *)dataFromHexString {
  const char *chars = [self UTF8String];
  int i = 0, len = self.length;

           NSMutableData *data = [NSMutableData dataWithCapacity:len / 2];
           char byteChars[3] = {'\0','\0','\0'};
           unsigned long wholeByte;
  
           while (i < len) {
               byteChars[0] = chars[i++];
               byteChars[1] = chars[i++];
               wholeByte = strtoul(byteChars, NULL, 16);
               [data appendBytes:&wholeByte length:1];
           }
  
           return data;
       }
  

• Details about CommonCrypto

• IV has to be 16 bytes.

• On iOS, you should be using the CCCrypt*() functions for AES.