File	Doc	Category	Size	Date	Package
BufferedBlockCipher.java	API Doc	Azureus 3.0.3.4	8762	Tue Jun 08 05:12:58 BST 2004	org.bouncycastle.crypto

BufferedBlockCipher

• java.lang.Object

Fields Summary
protected byte[]	buf
protected int	bufOff
protected boolean	forEncryption
protected BlockCipher	cipher
protected boolean	partialBlockOkay
protected boolean	pgpCFB

Constructors Summary
protected BufferedBlockCipher() constructor for subclasses
public BufferedBlockCipher(BlockCipher cipher) Create a buffered block cipher without padding. param cipher the underlying block cipher this buffering object wraps. param padded true if the buffer should add, or remove, pad bytes, false otherwise. this.cipher = cipher; buf = new byte[cipher.getBlockSize()]; bufOff = 0; // // check if we can handle partial blocks on doFinal. // String name = cipher.getAlgorithmName(); int idx = name.indexOf('/") + 1; pgpCFB = (idx > 0 && name.startsWith("PGP", idx)); if (pgpCFB) { partialBlockOkay = true; } else { partialBlockOkay = (idx > 0 && (name.startsWith("CFB", idx) || name.startsWith("OFB", idx) || name.startsWith("OpenPGP", idx))); }

Methods Summary
public int	doFinal(byte[] out, int outOff) Process the last block in the buffer. param out the array the block currently being held is copied into. param outOff the offset at which the copying starts. return the number of output bytes copied to out. exception DataLengthException if there is insufficient space in out for the output, or the input is not block size aligned and should be. exception IllegalStateException if the underlying cipher is not initialised. exception InvalidCipherTextException if padding is expected and not found. exception DataLengthException if the input is not block size aligned. int resultLen = 0; if (outOff + bufOff > out.length) { throw new DataLengthException("output buffer too short for doFinal()"); } if (bufOff != 0 && partialBlockOkay) { cipher.processBlock(buf, 0, buf, 0); resultLen = bufOff; bufOff = 0; System.arraycopy(buf, 0, out, outOff, resultLen); } else if (bufOff != 0) { throw new DataLengthException("data not block size aligned"); } reset(); return resultLen;
public int	getBlockSize() return the blocksize for the underlying cipher. return the blocksize for the underlying cipher. return cipher.getBlockSize();
public int	getOutputSize(int len) return the size of the output buffer required for an update plus a doFinal with an input of len bytes. param len the length of the input. return the space required to accommodate a call to update and doFinal with len bytes of input. int total = len + bufOff; int leftOver; if (pgpCFB) { leftOver = total % buf.length - (cipher.getBlockSize() + 2); } else { leftOver = total % buf.length; if (leftOver == 0) { return total; } } return total - leftOver + buf.length;
public BlockCipher	getUnderlyingCipher() return the cipher this object wraps. return the cipher this object wraps. return cipher;
public int	getUpdateOutputSize(int len) return the size of the output buffer required for an update an input of len bytes. param len the length of the input. return the space required to accommodate a call to update with len bytes of input. int total = len + bufOff; int leftOver; if (pgpCFB) { leftOver = total % buf.length - (cipher.getBlockSize() + 2); } else { leftOver = total % buf.length; } return total - leftOver;
public void	init(boolean forEncryption, CipherParameters params) initialise the cipher. param forEncryption if true the cipher is initialised for encryption, if false for decryption. param param the key and other data required by the cipher. exception IllegalArgumentException if the params argument is inappropriate. this.forEncryption = forEncryption; reset(); cipher.init(forEncryption, params);
public int	processByte(byte in, byte[] out, int outOff) process a single byte, producing an output block if neccessary. param in the input byte. param out the space for any output that might be produced. param outOff the offset from which the output will be copied. return the number of output bytes copied to out. exception DataLengthException if there isn't enough space in out. exception IllegalStateException if the cipher isn't initialised. int resultLen = 0; buf[bufOff++] = in; if (bufOff == buf.length) { resultLen = cipher.processBlock(buf, 0, out, outOff); bufOff = 0; } return resultLen;
public int	processBytes(byte[] in, int inOff, int len, byte[] out, int outOff) process an array of bytes, producing output if necessary. param in the input byte array. param inOff the offset at which the input data starts. param len the number of bytes to be copied out of the input array. param out the space for any output that might be produced. param outOff the offset from which the output will be copied. return the number of output bytes copied to out. exception DataLengthException if there isn't enough space in out. exception IllegalStateException if the cipher isn't initialised. if (len < 0) { throw new IllegalArgumentException("Can't have a negative input length!"); } int blockSize = getBlockSize(); int length = getUpdateOutputSize(len); if (length > 0) { if ((outOff + length) > out.length) { throw new DataLengthException("output buffer too short"); } } int resultLen = 0; int gapLen = buf.length - bufOff; if (len > gapLen) { System.arraycopy(in, inOff, buf, bufOff, gapLen); resultLen += cipher.processBlock(buf, 0, out, outOff); bufOff = 0; len -= gapLen; inOff += gapLen; while (len > buf.length) { resultLen += cipher.processBlock(in, inOff, out, outOff + resultLen); len -= blockSize; inOff += blockSize; } } System.arraycopy(in, inOff, buf, bufOff, len); bufOff += len; if (bufOff == buf.length) { resultLen += cipher.processBlock(buf, 0, out, outOff + resultLen); bufOff = 0; } return resultLen;
public void	reset() Reset the buffer and cipher. After resetting the object is in the same state as it was after the last init (if there was one). // // clean the buffer. // for (int i = 0; i < buf.length; i++) { buf[i] = 0; } bufOff = 0; // // reset the underlying cipher. // cipher.reset();