| package org.bouncycastle.crypto.macs; |
| |
| import org.bouncycastle.crypto.BlockCipher; |
| import org.bouncycastle.crypto.CipherParameters; |
| import org.bouncycastle.crypto.DataLengthException; |
| import org.bouncycastle.crypto.Mac; |
| import org.bouncycastle.crypto.OutputLengthException; |
| import org.bouncycastle.crypto.paddings.BlockCipherPadding; |
| import org.bouncycastle.crypto.params.ParametersWithIV; |
| |
| /** |
| * implements a Cipher-FeedBack (CFB) mode on top of a simple cipher. |
| */ |
| class MacCFBBlockCipher |
| { |
| private byte[] IV; |
| private byte[] cfbV; |
| private byte[] cfbOutV; |
| |
| private int blockSize; |
| private BlockCipher cipher = null; |
| |
| /** |
| * Basic constructor. |
| * |
| * @param cipher the block cipher to be used as the basis of the |
| * feedback mode. |
| * @param blockSize the block size in bits (note: a multiple of 8) |
| */ |
| public MacCFBBlockCipher( |
| BlockCipher cipher, |
| int bitBlockSize) |
| { |
| this.cipher = cipher; |
| this.blockSize = bitBlockSize / 8; |
| |
| this.IV = new byte[cipher.getBlockSize()]; |
| this.cfbV = new byte[cipher.getBlockSize()]; |
| this.cfbOutV = new byte[cipher.getBlockSize()]; |
| } |
| |
| /** |
| * Initialise the cipher and, possibly, the initialisation vector (IV). |
| * If an IV isn't passed as part of the parameter, the IV will be all zeros. |
| * An IV which is too short is handled in FIPS compliant fashion. |
| * |
| * @param param the key and other data required by the cipher. |
| * @exception IllegalArgumentException if the params argument is |
| * inappropriate. |
| */ |
| public void init( |
| CipherParameters params) |
| throws IllegalArgumentException |
| { |
| if (params instanceof ParametersWithIV) |
| { |
| ParametersWithIV ivParam = (ParametersWithIV)params; |
| byte[] iv = ivParam.getIV(); |
| |
| if (iv.length < IV.length) |
| { |
| System.arraycopy(iv, 0, IV, IV.length - iv.length, iv.length); |
| } |
| else |
| { |
| System.arraycopy(iv, 0, IV, 0, IV.length); |
| } |
| |
| reset(); |
| |
| cipher.init(true, ivParam.getParameters()); |
| } |
| else |
| { |
| reset(); |
| |
| cipher.init(true, params); |
| } |
| } |
| |
| /** |
| * return the algorithm name and mode. |
| * |
| * @return the name of the underlying algorithm followed by "/CFB" |
| * and the block size in bits. |
| */ |
| public String getAlgorithmName() |
| { |
| return cipher.getAlgorithmName() + "/CFB" + (blockSize * 8); |
| } |
| |
| /** |
| * return the block size we are operating at. |
| * |
| * @return the block size we are operating at (in bytes). |
| */ |
| public int getBlockSize() |
| { |
| return blockSize; |
| } |
| |
| /** |
| * Process one block of input from the array in and write it to |
| * the out array. |
| * |
| * @param in the array containing the input data. |
| * @param inOff offset into the in array the data starts at. |
| * @param out the array the output data will be copied into. |
| * @param outOff the offset into the out array the output will start at. |
| * @exception DataLengthException if there isn't enough data in in, or |
| * space in out. |
| * @exception IllegalStateException if the cipher isn't initialised. |
| * @return the number of bytes processed and produced. |
| */ |
| public int processBlock( |
| byte[] in, |
| int inOff, |
| byte[] out, |
| int outOff) |
| throws DataLengthException, IllegalStateException |
| { |
| if ((inOff + blockSize) > in.length) |
| { |
| throw new DataLengthException("input buffer too short"); |
| } |
| |
| if ((outOff + blockSize) > out.length) |
| { |
| throw new OutputLengthException("output buffer too short"); |
| } |
| |
| cipher.processBlock(cfbV, 0, cfbOutV, 0); |
| |
| // |
| // XOR the cfbV with the plaintext producing the cipher text |
| // |
| for (int i = 0; i < blockSize; i++) |
| { |
| out[outOff + i] = (byte)(cfbOutV[i] ^ in[inOff + i]); |
| } |
| |
| // |
| // change over the input block. |
| // |
| System.arraycopy(cfbV, blockSize, cfbV, 0, cfbV.length - blockSize); |
| System.arraycopy(out, outOff, cfbV, cfbV.length - blockSize, blockSize); |
| |
| return blockSize; |
| } |
| |
| /** |
| * reset the chaining vector back to the IV and reset the underlying |
| * cipher. |
| */ |
| public void reset() |
| { |
| System.arraycopy(IV, 0, cfbV, 0, IV.length); |
| |
| cipher.reset(); |
| } |
| |
| void getMacBlock( |
| byte[] mac) |
| { |
| cipher.processBlock(cfbV, 0, mac, 0); |
| } |
| } |
| |
| public class CFBBlockCipherMac |
| implements Mac |
| { |
| private byte[] mac; |
| |
| private byte[] buf; |
| private int bufOff; |
| private MacCFBBlockCipher cipher; |
| private BlockCipherPadding padding = null; |
| |
| |
| private int macSize; |
| |
| /** |
| * create a standard MAC based on a CFB block cipher. This will produce an |
| * authentication code half the length of the block size of the cipher, with |
| * the CFB mode set to 8 bits. |
| * |
| * @param cipher the cipher to be used as the basis of the MAC generation. |
| */ |
| public CFBBlockCipherMac( |
| BlockCipher cipher) |
| { |
| this(cipher, 8, (cipher.getBlockSize() * 8) / 2, null); |
| } |
| |
| /** |
| * create a standard MAC based on a CFB block cipher. This will produce an |
| * authentication code half the length of the block size of the cipher, with |
| * the CFB mode set to 8 bits. |
| * |
| * @param cipher the cipher to be used as the basis of the MAC generation. |
| * @param padding the padding to be used. |
| */ |
| public CFBBlockCipherMac( |
| BlockCipher cipher, |
| BlockCipherPadding padding) |
| { |
| this(cipher, 8, (cipher.getBlockSize() * 8) / 2, padding); |
| } |
| |
| /** |
| * create a standard MAC based on a block cipher with the size of the |
| * MAC been given in bits. This class uses CFB mode as the basis for the |
| * MAC generation. |
| * <p> |
| * Note: the size of the MAC must be at least 24 bits (FIPS Publication 81), |
| * or 16 bits if being used as a data authenticator (FIPS Publication 113), |
| * and in general should be less than the size of the block cipher as it reduces |
| * the chance of an exhaustive attack (see Handbook of Applied Cryptography). |
| * |
| * @param cipher the cipher to be used as the basis of the MAC generation. |
| * @param cfbBitSize the size of an output block produced by the CFB mode. |
| * @param macSizeInBits the size of the MAC in bits, must be a multiple of 8. |
| */ |
| public CFBBlockCipherMac( |
| BlockCipher cipher, |
| int cfbBitSize, |
| int macSizeInBits) |
| { |
| this(cipher, cfbBitSize, macSizeInBits, null); |
| } |
| |
| /** |
| * create a standard MAC based on a block cipher with the size of the |
| * MAC been given in bits. This class uses CFB mode as the basis for the |
| * MAC generation. |
| * <p> |
| * Note: the size of the MAC must be at least 24 bits (FIPS Publication 81), |
| * or 16 bits if being used as a data authenticator (FIPS Publication 113), |
| * and in general should be less than the size of the block cipher as it reduces |
| * the chance of an exhaustive attack (see Handbook of Applied Cryptography). |
| * |
| * @param cipher the cipher to be used as the basis of the MAC generation. |
| * @param cfbBitSize the size of an output block produced by the CFB mode. |
| * @param macSizeInBits the size of the MAC in bits, must be a multiple of 8. |
| * @param padding a padding to be used. |
| */ |
| public CFBBlockCipherMac( |
| BlockCipher cipher, |
| int cfbBitSize, |
| int macSizeInBits, |
| BlockCipherPadding padding) |
| { |
| if ((macSizeInBits % 8) != 0) |
| { |
| throw new IllegalArgumentException("MAC size must be multiple of 8"); |
| } |
| |
| mac = new byte[cipher.getBlockSize()]; |
| |
| this.cipher = new MacCFBBlockCipher(cipher, cfbBitSize); |
| this.padding = padding; |
| this.macSize = macSizeInBits / 8; |
| |
| buf = new byte[this.cipher.getBlockSize()]; |
| bufOff = 0; |
| } |
| |
| public String getAlgorithmName() |
| { |
| return cipher.getAlgorithmName(); |
| } |
| |
| public void init( |
| CipherParameters params) |
| { |
| reset(); |
| |
| cipher.init(params); |
| } |
| |
| public int getMacSize() |
| { |
| return macSize; |
| } |
| |
| public void update( |
| byte in) |
| { |
| if (bufOff == buf.length) |
| { |
| cipher.processBlock(buf, 0, mac, 0); |
| bufOff = 0; |
| } |
| |
| buf[bufOff++] = in; |
| } |
| |
| public void update( |
| byte[] in, |
| int inOff, |
| int len) |
| { |
| if (len < 0) |
| { |
| throw new IllegalArgumentException("Can't have a negative input length!"); |
| } |
| |
| int blockSize = cipher.getBlockSize(); |
| int resultLen = 0; |
| int gapLen = blockSize - bufOff; |
| |
| if (len > gapLen) |
| { |
| System.arraycopy(in, inOff, buf, bufOff, gapLen); |
| |
| resultLen += cipher.processBlock(buf, 0, mac, 0); |
| |
| bufOff = 0; |
| len -= gapLen; |
| inOff += gapLen; |
| |
| while (len > blockSize) |
| { |
| resultLen += cipher.processBlock(in, inOff, mac, 0); |
| |
| len -= blockSize; |
| inOff += blockSize; |
| } |
| } |
| |
| System.arraycopy(in, inOff, buf, bufOff, len); |
| |
| bufOff += len; |
| } |
| |
| public int doFinal( |
| byte[] out, |
| int outOff) |
| { |
| int blockSize = cipher.getBlockSize(); |
| |
| // |
| // pad with zeroes |
| // |
| if (this.padding == null) |
| { |
| while (bufOff < blockSize) |
| { |
| buf[bufOff] = 0; |
| bufOff++; |
| } |
| } |
| else |
| { |
| padding.addPadding(buf, bufOff); |
| } |
| |
| cipher.processBlock(buf, 0, mac, 0); |
| |
| cipher.getMacBlock(mac); |
| |
| System.arraycopy(mac, 0, out, outOff, macSize); |
| |
| reset(); |
| |
| return macSize; |
| } |
| |
| /** |
| * Reset the mac generator. |
| */ |
| public void reset() |
| { |
| /* |
| * clean the buffer. |
| */ |
| for (int i = 0; i < buf.length; i++) |
| { |
| buf[i] = 0; |
| } |
| |
| bufOff = 0; |
| |
| /* |
| * reset the underlying cipher. |
| */ |
| cipher.reset(); |
| } |
| } |