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package org.bouncycastle.crypto.modes;
import java.io.ByteArrayOutputStream;
import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.InvalidCipherTextException;
import org.bouncycastle.crypto.Mac;
import org.bouncycastle.crypto.OutputLengthException;
import org.bouncycastle.crypto.macs.CBCBlockCipherMac;
import org.bouncycastle.crypto.params.AEADParameters;
import org.bouncycastle.crypto.params.ParametersWithIV;
import org.bouncycastle.util.Arrays;
/**
* Implements the Counter with Cipher Block Chaining mode (CCM) detailed in
* NIST Special Publication 800-38C.
*
* Note: this mode is a packet mode - it needs all the data up front.
*/
public class CCMBlockCipher
implements AEADBlockCipher
{
private BlockCipher cipher;
private int blockSize;
private boolean forEncryption;
private byte[] nonce;
private byte[] initialAssociatedText;
private int macSize;
private CipherParameters keyParam;
private byte[] macBlock;
private ExposedByteArrayOutputStream associatedText = new ExposedByteArrayOutputStream();
private ExposedByteArrayOutputStream data = new ExposedByteArrayOutputStream();
/**
* Basic constructor.
*
* @param c the block cipher to be used.
*/
public CCMBlockCipher(BlockCipher c)
{
this.cipher = c;
this.blockSize = c.getBlockSize();
this.macBlock = new byte[blockSize];
if (blockSize != 16)
{
throw new IllegalArgumentException("cipher required with a block size of 16.");
}
}
/**
* return the underlying block cipher that we are wrapping.
*
* @return the underlying block cipher that we are wrapping.
*/
public BlockCipher getUnderlyingCipher()
{
return cipher;
}
public void init(boolean forEncryption, CipherParameters params)
throws IllegalArgumentException
{
this.forEncryption = forEncryption;
CipherParameters cipherParameters;
if (params instanceof AEADParameters)
{
AEADParameters param = (AEADParameters)params;
nonce = param.getNonce();
initialAssociatedText = param.getAssociatedText();
macSize = param.getMacSize() / 8;
cipherParameters = param.getKey();
}
else if (params instanceof ParametersWithIV)
{
ParametersWithIV param = (ParametersWithIV)params;
nonce = param.getIV();
initialAssociatedText = null;
macSize = macBlock.length / 2;
cipherParameters = param.getParameters();
}
else
{
throw new IllegalArgumentException("invalid parameters passed to CCM: " + params.getClass().getName());
}
// NOTE: Very basic support for key re-use, but no performance gain from it
if (cipherParameters != null)
{
keyParam = cipherParameters;
}
if (nonce == null || nonce.length < 7 || nonce.length > 13)
{
throw new IllegalArgumentException("nonce must have length from 7 to 13 octets");
}
reset();
}
public String getAlgorithmName()
{
return cipher.getAlgorithmName() + "/CCM";
}
public void processAADByte(byte in)
{
associatedText.write(in);
}
public void processAADBytes(byte[] in, int inOff, int len)
{
// TODO: Process AAD online
associatedText.write(in, inOff, len);
}
public int processByte(byte in, byte[] out, int outOff)
throws DataLengthException, IllegalStateException
{
data.write(in);
return 0;
}
public int processBytes(byte[] in, int inOff, int inLen, byte[] out, int outOff)
throws DataLengthException, IllegalStateException
{
if (in.length < (inOff + inLen))
{
throw new DataLengthException("Input buffer too short");
}
data.write(in, inOff, inLen);
return 0;
}
public int doFinal(byte[] out, int outOff)
throws IllegalStateException, InvalidCipherTextException
{
int len = processPacket(data.getBuffer(), 0, data.size(), out, outOff);
reset();
return len;
}
public void reset()
{
cipher.reset();
associatedText.reset();
data.reset();
}
/**
* Returns a byte array containing the mac calculated as part of the
* last encrypt or decrypt operation.
*
* @return the last mac calculated.
*/
public byte[] getMac()
{
byte[] mac = new byte[macSize];
System.arraycopy(macBlock, 0, mac, 0, mac.length);
return mac;
}
public int getUpdateOutputSize(int len)
{
return 0;
}
public int getOutputSize(int len)
{
int totalData = len + data.size();
if (forEncryption)
{
return totalData + macSize;
}
return totalData < macSize ? 0 : totalData - macSize;
}
/**
* Process a packet of data for either CCM decryption or encryption.
*
* @param in data for processing.
* @param inOff offset at which data starts in the input array.
* @param inLen length of the data in the input array.
* @return a byte array containing the processed input..
* @throws IllegalStateException if the cipher is not appropriately set up.
* @throws InvalidCipherTextException if the input data is truncated or the mac check fails.
*/
public byte[] processPacket(byte[] in, int inOff, int inLen)
throws IllegalStateException, InvalidCipherTextException
{
byte[] output;
if (forEncryption)
{
output = new byte[inLen + macSize];
}
else
{
if (inLen < macSize)
{
throw new InvalidCipherTextException("data too short");
}
output = new byte[inLen - macSize];
}
processPacket(in, inOff, inLen, output, 0);
return output;
}
/**
* Process a packet of data for either CCM decryption or encryption.
*
* @param in data for processing.
* @param inOff offset at which data starts in the input array.
* @param inLen length of the data in the input array.
* @param output output array.
* @param outOff offset into output array to start putting processed bytes.
* @return the number of bytes added to output.
* @throws IllegalStateException if the cipher is not appropriately set up.
* @throws InvalidCipherTextException if the input data is truncated or the mac check fails.
* @throws DataLengthException if output buffer too short.
*/
public int processPacket(byte[] in, int inOff, int inLen, byte[] output, int outOff)
throws IllegalStateException, InvalidCipherTextException, DataLengthException
{
// TODO: handle null keyParam (e.g. via RepeatedKeySpec)
// Need to keep the CTR and CBC Mac parts around and reset
if (keyParam == null)
{
throw new IllegalStateException("CCM cipher unitialized.");
}
int n = nonce.length;
int q = 15 - n;
if (q < 4)
{
int limitLen = 1 << (8 * q);
if (inLen >= limitLen)
{
throw new IllegalStateException("CCM packet too large for choice of q.");
}
}
byte[] iv = new byte[blockSize];
iv[0] = (byte)((q - 1) & 0x7);
System.arraycopy(nonce, 0, iv, 1, nonce.length);
BlockCipher ctrCipher = new SICBlockCipher(cipher);
ctrCipher.init(forEncryption, new ParametersWithIV(keyParam, iv));
int outputLen;
int inIndex = inOff;
int outIndex = outOff;
if (forEncryption)
{
outputLen = inLen + macSize;
if (output.length < (outputLen + outOff))
{
throw new OutputLengthException("Output buffer too short.");
}
calculateMac(in, inOff, inLen, macBlock);
byte[] encMac = new byte[blockSize];
ctrCipher.processBlock(macBlock, 0, encMac, 0); // S0
while (inIndex < (inOff + inLen - blockSize)) // S1...
{
ctrCipher.processBlock(in, inIndex, output, outIndex);
outIndex += blockSize;
inIndex += blockSize;
}
byte[] block = new byte[blockSize];
System.arraycopy(in, inIndex, block, 0, inLen + inOff - inIndex);
ctrCipher.processBlock(block, 0, block, 0);
System.arraycopy(block, 0, output, outIndex, inLen + inOff - inIndex);
System.arraycopy(encMac, 0, output, outOff + inLen, macSize);
}
else
{
if (inLen < macSize)
{
throw new InvalidCipherTextException("data too short");
}
outputLen = inLen - macSize;
if (output.length < (outputLen + outOff))
{
throw new OutputLengthException("Output buffer too short.");
}
System.arraycopy(in, inOff + outputLen, macBlock, 0, macSize);
ctrCipher.processBlock(macBlock, 0, macBlock, 0);
for (int i = macSize; i != macBlock.length; i++)
{
macBlock[i] = 0;
}
while (inIndex < (inOff + outputLen - blockSize))
{
ctrCipher.processBlock(in, inIndex, output, outIndex);
outIndex += blockSize;
inIndex += blockSize;
}
byte[] block = new byte[blockSize];
System.arraycopy(in, inIndex, block, 0, outputLen - (inIndex - inOff));
ctrCipher.processBlock(block, 0, block, 0);
System.arraycopy(block, 0, output, outIndex, outputLen - (inIndex - inOff));
byte[] calculatedMacBlock = new byte[blockSize];
calculateMac(output, outOff, outputLen, calculatedMacBlock);
if (!Arrays.constantTimeAreEqual(macBlock, calculatedMacBlock))
{
throw new InvalidCipherTextException("mac check in CCM failed");
}
}
return outputLen;
}
private int calculateMac(byte[] data, int dataOff, int dataLen, byte[] macBlock)
{
Mac cMac = new CBCBlockCipherMac(cipher, macSize * 8);
cMac.init(keyParam);
//
// build b0
//
byte[] b0 = new byte[16];
if (hasAssociatedText())
{
b0[0] |= 0x40;
}
b0[0] |= (((cMac.getMacSize() - 2) / 2) & 0x7) << 3;
b0[0] |= ((15 - nonce.length) - 1) & 0x7;
System.arraycopy(nonce, 0, b0, 1, nonce.length);
int q = dataLen;
int count = 1;
while (q > 0)
{
b0[b0.length - count] = (byte)(q & 0xff);
q >>>= 8;
count++;
}
cMac.update(b0, 0, b0.length);
//
// process associated text
//
if (hasAssociatedText())
{
int extra;
int textLength = getAssociatedTextLength();
if (textLength < ((1 << 16) - (1 << 8)))
{
cMac.update((byte)(textLength >> 8));
cMac.update((byte)textLength);
extra = 2;
}
else // can't go any higher than 2^32
{
cMac.update((byte)0xff);
cMac.update((byte)0xfe);
cMac.update((byte)(textLength >> 24));
cMac.update((byte)(textLength >> 16));
cMac.update((byte)(textLength >> 8));
cMac.update((byte)textLength);
extra = 6;
}
if (initialAssociatedText != null)
{
cMac.update(initialAssociatedText, 0, initialAssociatedText.length);
}
if (associatedText.size() > 0)
{
cMac.update(associatedText.getBuffer(), 0, associatedText.size());
}
extra = (extra + textLength) % 16;
if (extra != 0)
{
for (int i = extra; i != 16; i++)
{
cMac.update((byte)0x00);
}
}
}
//
// add the text
//
cMac.update(data, dataOff, dataLen);
return cMac.doFinal(macBlock, 0);
}
private int getAssociatedTextLength()
{
return associatedText.size() + ((initialAssociatedText == null) ? 0 : initialAssociatedText.length);
}
private boolean hasAssociatedText()
{
return getAssociatedTextLength() > 0;
}
private class ExposedByteArrayOutputStream
extends ByteArrayOutputStream
{
public ExposedByteArrayOutputStream()
{
}
public byte[] getBuffer()
{
return this.buf;
}
}
}