diff options
Diffstat (limited to 'app/src/main/java/com/trilead/ssh2/crypto/cipher/CTRMode.java')
-rw-r--r-- | app/src/main/java/com/trilead/ssh2/crypto/cipher/CTRMode.java | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/app/src/main/java/com/trilead/ssh2/crypto/cipher/CTRMode.java b/app/src/main/java/com/trilead/ssh2/crypto/cipher/CTRMode.java new file mode 100644 index 0000000..8541c8d --- /dev/null +++ b/app/src/main/java/com/trilead/ssh2/crypto/cipher/CTRMode.java @@ -0,0 +1,62 @@ + +package com.trilead.ssh2.crypto.cipher; + +/** + * This is CTR mode as described in draft-ietf-secsh-newmodes-XY.txt + * + * @author Christian Plattner, plattner@trilead.com + * @version $Id: CTRMode.java,v 1.1 2007/10/15 12:49:55 cplattne Exp $ + */ +public class CTRMode implements BlockCipher +{ + byte[] X; + byte[] Xenc; + + BlockCipher bc; + int blockSize; + boolean doEncrypt; + + int count = 0; + + public void init(boolean forEncryption, byte[] key) + { + } + + public CTRMode(BlockCipher tc, byte[] iv, boolean doEnc) throws IllegalArgumentException + { + bc = tc; + blockSize = bc.getBlockSize(); + doEncrypt = doEnc; + + if (blockSize != iv.length) + throw new IllegalArgumentException("IV must be " + blockSize + " bytes long! (currently " + iv.length + ")"); + + X = new byte[blockSize]; + Xenc = new byte[blockSize]; + + System.arraycopy(iv, 0, X, 0, blockSize); + } + + public final int getBlockSize() + { + return blockSize; + } + + public final void transformBlock(byte[] src, int srcoff, byte[] dst, int dstoff) + { + bc.transformBlock(X, 0, Xenc, 0); + + for (int i = 0; i < blockSize; i++) + { + dst[dstoff + i] = (byte) (src[srcoff + i] ^ Xenc[i]); + } + + for (int i = (blockSize - 1); i >= 0; i--) + { + X[i]++; + if (X[i] != 0) + break; + + } + } +} |