1b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallampackage org.bouncycastle.crypto.paddings; 2b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 3b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallamimport java.security.SecureRandom; 4b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 5b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallamimport org.bouncycastle.crypto.InvalidCipherTextException; 6b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 7b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam/** 8b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * A padder that adds ISO10126-2 padding to a block. 9b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam */ 10b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallampublic class ISO10126d2Padding 11b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam implements BlockCipherPadding 12b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam{ 13b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam SecureRandom random; 14b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 15b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam /** 16b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * Initialise the padder. 17b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * 18b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * @param random a SecureRandom if available. 19b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam */ 20b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam public void init(SecureRandom random) 21b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam throws IllegalArgumentException 22b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 23b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam if (random != null) 24b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 25b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam this.random = random; 26b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 27b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam else 28b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 29b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam this.random = new SecureRandom(); 30b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 31b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 32b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 33b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam /** 34b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * Return the name of the algorithm the padder implements. 35b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * 36b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * @return the name of the algorithm the padder implements. 37b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam */ 38b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam public String getPaddingName() 39b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 40b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam return "ISO10126-2"; 41b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 42b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 43b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam /** 44b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * add the pad bytes to the passed in block, returning the 45b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * number of bytes added. 46b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam */ 47b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam public int addPadding( 48b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam byte[] in, 49b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam int inOff) 50b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 51b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam byte code = (byte)(in.length - inOff); 52b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 53b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam while (inOff < (in.length - 1)) 54b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 55b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam in[inOff] = (byte)random.nextInt(); 56b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam inOff++; 57b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 58b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 59b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam in[inOff] = code; 60b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 61b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam return code; 62b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 63b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 64b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam /** 65b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam * return the number of pad bytes present in the block. 66b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam */ 67b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam public int padCount(byte[] in) 68b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam throws InvalidCipherTextException 69b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 70b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam int count = in[in.length - 1] & 0xff; 71b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 72b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam if (count > in.length) 73b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam { 74b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam throw new InvalidCipherTextException("pad block corrupted"); 75b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 76b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam 77b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam return count; 78b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam } 79b61a96e7ef1a78acf013bbf08fe537e5b5f129caPeter Hallam} 80