1 files changed, 455 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/modes/PGPCFBBlockCipher.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/modes/PGPCFBBlockCipher.java
new file mode 100644
index 000000000..370ce40d9
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/modes/PGPCFBBlockCipher.java
@@ -0,0 +1,455 @@
+package org.spongycastle.crypto.modes;
+
+import org.spongycastle.crypto.BlockCipher;
+import org.spongycastle.crypto.CipherParameters;
+import org.spongycastle.crypto.DataLengthException;
+import org.spongycastle.crypto.params.ParametersWithIV;
+
+/**
+ * Implements OpenPGP's rather strange version of Cipher-FeedBack (CFB) mode on top of a simple cipher. For further info see <a href="http://www.ietf.org/rfc/rfc2440.html">RFC 2440</a>.
+ */
+public class PGPCFBBlockCipher
+    implements BlockCipher
+{
+    private byte[] IV;
+    private byte[] FR;
+    private byte[] FRE;
+    private byte[] tmp;
+
+    private BlockCipher cipher;
+
+    private int count;
+    private int blockSize;
+    private boolean forEncryption;
+    
+    private boolean inlineIv; // if false we don't need to prepend an IV
+
+    /**
+     * Basic constructor.
+     *
+     * @param cipher the block cipher to be used as the basis of the
+     * feedback mode.
+     * @param inlineIv if true this is for PGP CFB with a prepended iv.
+     */
+    public PGPCFBBlockCipher(
+        BlockCipher cipher,
+        boolean     inlineIv)
+    {
+        this.cipher = cipher;
+        this.inlineIv = inlineIv;
+
+        this.blockSize = cipher.getBlockSize();
+        this.IV = new byte[blockSize];
+        this.FR = new byte[blockSize];
+        this.FRE = new byte[blockSize];
+        this.tmp = new byte[blockSize];
+    }
+
+    /**
+     * return the underlying block cipher that we are wrapping.
+     *
+     * @return the underlying block cipher that we are wrapping.
+     */
+    public BlockCipher getUnderlyingCipher()
+    {
+        return cipher;
+    }
+    
+    /**
+     * return the algorithm name and mode.
+     *
+     * @return the name of the underlying algorithm followed by "/PGPCFB"
+     * and the block size in bits.
+     */
+    public String getAlgorithmName()
+    {
+        if (inlineIv)
+        {
+            return cipher.getAlgorithmName() + "/PGPCFBwithIV";
+        }
+        else
+        {
+            return cipher.getAlgorithmName() + "/PGPCFB";
+        }
+    }
+    
+    /**
+     * return the block size we are operating at.
+     *
+     * @return the block size we are operating at (in bytes).
+     */
+    public int getBlockSize()
+    {
+        return cipher.getBlockSize();
+    }
+
+    /**
+     * 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 (inlineIv)
+        {
+            return (forEncryption) ? encryptBlockWithIV(in, inOff, out, outOff) : decryptBlockWithIV(in, inOff, out, outOff);
+        }
+        else
+        {
+            return (forEncryption) ? encryptBlock(in, inOff, out, outOff) : decryptBlock(in, inOff, out, outOff);
+        }
+    }
+    
+    /**
+     * reset the chaining vector back to the IV and reset the underlying
+     * cipher.
+     */
+    public void reset()
+    {
+        count = 0;
+
+        for (int i = 0; i != FR.length; i++)
+        {
+            if (inlineIv)
+            {
+                FR[i] = 0;
+            }
+            else
+            {
+                FR[i] = IV[i]; // if simple mode, key is IV (even if this is zero)
+            }
+        }
+
+        cipher.reset();
+    }
+
+    /**
+     * 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 forEncryption if true the cipher is initialised for
+     *  encryption, if false for decryption.
+     * @param params the key and other data required by the cipher.
+     * @exception IllegalArgumentException if the params argument is
+     * inappropriate.
+     */
+    public void init(
+        boolean forEncryption,
+        CipherParameters params)
+        throws IllegalArgumentException
+    {
+        this.forEncryption = forEncryption;
+     
+        if (params instanceof ParametersWithIV)
+        {
+                ParametersWithIV ivParam = (ParametersWithIV)params;
+                byte[]      iv = ivParam.getIV();
+
+                if (iv.length < IV.length)
+                {
+                    // prepend the supplied IV with zeros (per FIPS PUB 81)
+                    System.arraycopy(iv, 0, IV, IV.length - iv.length, iv.length);
+                    for (int i = 0; i < IV.length - iv.length; i++)
+                    {
+                            IV[i] = 0;
+                    }
+                }
+                else
+                {
+                    System.arraycopy(iv, 0, IV, 0, IV.length);
+                }
+
+                reset();
+
+                cipher.init(true, ivParam.getParameters());
+        }
+        else
+        {
+                reset();
+
+                cipher.init(true, params);
+        }
+    }
+    
+    /**
+     * Encrypt one byte of data according to CFB mode.
+     * @param data the byte to encrypt
+     * @param blockOff where am i in the current block, determines when to resync the block
+     * @returns the encrypted byte
+     */
+    private byte encryptByte(byte data, int blockOff)
+    {
+        return (byte)(FRE[blockOff] ^ data);
+    }
+    
+    /**
+     * Do the appropriate processing for CFB IV mode encryption.
+     *
+     * @param in the array containing the data to be encrypted.
+     * @param inOff offset into the in array the data starts at.
+     * @param out the array the encrypted 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.
+     */
+    private int encryptBlockWithIV(
+        byte[] in,
+        int inOff,
+        byte[] out,
+        int outOff)
+        throws DataLengthException, IllegalStateException
+    {
+        if ((inOff + blockSize) > in.length)
+        {
+            throw new DataLengthException("input buffer too short");
+        }
+
+        if (count == 0)
+        {
+            if ((outOff + 2 * blockSize + 2) > out.length)
+            {
+                throw new DataLengthException("output buffer too short");
+            }
+
+            cipher.processBlock(FR, 0, FRE, 0);
+
+            for (int n = 0; n < blockSize; n++) 
+            {
+                out[outOff + n] = encryptByte(IV[n], n);
+            }
+            
+            System.arraycopy(out, outOff, FR, 0, blockSize);
+
+            cipher.processBlock(FR, 0, FRE, 0);
+
+            out[outOff + blockSize] = encryptByte(IV[blockSize - 2], 0);
+            out[outOff + blockSize + 1] = encryptByte(IV[blockSize - 1], 1);
+
+            System.arraycopy(out, outOff + 2, FR, 0, blockSize);
+            
+            cipher.processBlock(FR, 0, FRE, 0);
+
+            for (int n = 0; n < blockSize; n++) 
+            {
+                out[outOff + blockSize + 2 + n] = encryptByte(in[inOff + n], n);
+            }
+
+            System.arraycopy(out, outOff + blockSize + 2, FR, 0, blockSize);
+
+            count += 2 * blockSize + 2;
+
+            return 2 * blockSize + 2;
+        }
+        else if (count >= blockSize + 2)
+        {
+            if ((outOff + blockSize) > out.length)
+            {
+                throw new DataLengthException("output buffer too short");
+            }
+
+            cipher.processBlock(FR, 0, FRE, 0);
+
+            for (int n = 0; n < blockSize; n++) 
+            {
+                out[outOff + n] = encryptByte(in[inOff + n], n);
+            }
+            
+            System.arraycopy(out, outOff, FR, 0, blockSize);
+        }
+        
+        return blockSize;
+    }
+
+    /**
+     * Do the appropriate processing for CFB IV mode decryption.
+     *
+     * @param in the array containing the data to be decrypted.
+     * @param inOff offset into the in array the data starts at.
+     * @param out the array the encrypted 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.
+     */
+    private int decryptBlockWithIV(
+        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 DataLengthException("output buffer too short");
+        }
+        
+        if (count == 0)
+        {
+            for (int n = 0; n < blockSize; n++) 
+            {
+                FR[n] = in[inOff + n];
+            }
+            
+            cipher.processBlock(FR, 0, FRE, 0);
+
+            count += blockSize;
+
+            return 0;
+        }
+        else if (count == blockSize)
+        {
+            // copy in buffer so that this mode works if in and out are the same 
+            System.arraycopy(in, inOff, tmp, 0, blockSize);
+        
+            System.arraycopy(FR, 2, FR, 0, blockSize - 2);
+            
+            FR[blockSize - 2] = tmp[0];
+            FR[blockSize - 1] = tmp[1];
+
+            cipher.processBlock(FR, 0, FRE, 0);
+
+            for (int n = 0; n < blockSize - 2; n++) 
+            {
+                out[outOff + n] = encryptByte(tmp[n + 2], n);
+            }
+
+            System.arraycopy(tmp, 2, FR, 0, blockSize - 2);
+
+            count += 2;
+
+            return blockSize - 2;
+        }
+        else if (count >= blockSize + 2)
+        {
+            // copy in buffer so that this mode works if in and out are the same 
+            System.arraycopy(in, inOff, tmp, 0, blockSize);
+
+            out[outOff + 0] = encryptByte(tmp[0], blockSize - 2);
+            out[outOff + 1] = encryptByte(tmp[1], blockSize - 1);
+
+            System.arraycopy(tmp, 0, FR, blockSize - 2, 2);
+
+            cipher.processBlock(FR, 0, FRE, 0);
+            
+            for (int n = 0; n < blockSize - 2; n++) 
+            {
+                out[outOff + n + 2] = encryptByte(tmp[n + 2], n);
+            }
+            
+            System.arraycopy(tmp, 2, FR, 0, blockSize - 2);
+            
+        } 
+        
+        return blockSize;
+    }
+    
+    /**
+     * Do the appropriate processing for CFB mode encryption.
+     *
+     * @param in the array containing the data to be encrypted.
+     * @param inOff offset into the in array the data starts at.
+     * @param out the array the encrypted 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.
+     */
+    private int encryptBlock(
+        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 DataLengthException("output buffer too short");
+        }
+        
+        cipher.processBlock(FR, 0, FRE, 0);
+        for (int n = 0; n < blockSize; n++) 
+        {
+            out[outOff + n] = encryptByte(in[inOff + n], n);
+        }
+        
+        for (int n = 0; n < blockSize; n++) 
+        {
+            FR[n] = out[outOff + n];
+        }
+        
+        return blockSize;
+        
+    }
+    
+    /**
+     * Do the appropriate processing for CFB mode decryption.
+     *
+     * @param in the array containing the data to be decrypted.
+     * @param inOff offset into the in array the data starts at.
+     * @param out the array the encrypted 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.
+     */
+    private int decryptBlock(
+        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 DataLengthException("output buffer too short");
+        }
+        
+        cipher.processBlock(FR, 0, FRE, 0);
+        for (int n = 0; n < blockSize; n++) 
+        {
+            out[outOff + n] = encryptByte(in[inOff + n], n);
+        }
+        
+        for (int n = 0; n < blockSize; n++) 
+        {
+            FR[n] = in[inOff + n];
+        }
+        
+        return blockSize;
+        
+    }
+}