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* accompanied this code).
*
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package com.sun.crypto.provider;
import java.security.InvalidKeyException;
import javax.crypto.*;
/**
* This class represents a block cipher in one of its modes. It wraps
* a SymmetricCipher maintaining the mode state and providing
* the capability to encrypt amounts of data larger than a single block.
*
* @author Jan Luehe
* @see ElectronicCodeBook
* @see CipherBlockChaining
* @see CipherFeedback
* @see OutputFeedback
* @see PCBC
*/
abstract class FeedbackCipher {
// the embedded block cipher
final SymmetricCipher embeddedCipher;
// the block size of the embedded block cipher
final int blockSize;
// the initialization vector
byte[] iv;
FeedbackCipher(SymmetricCipher embeddedCipher) {
this.embeddedCipher = embeddedCipher;
blockSize = embeddedCipher.getBlockSize();
}
final SymmetricCipher getEmbeddedCipher() {
return embeddedCipher;
}
/**
* Gets the block size of the embedded cipher.
*
* @return the block size of the embedded cipher
*/
final int getBlockSize() {
return blockSize;
}
/**
* Gets the name of the feedback mechanism
*
* @return the name of the feedback mechanism
*/
abstract String getFeedback();
/**
* Save the current content of this cipher.
*/
abstract void save();
/**
* Restores the content of this cipher to the previous saved one.
*/
abstract void restore();
/**
* Initializes the cipher in the specified mode with the given key
* and iv.
*
* @param decrypting flag indicating encryption or decryption mode
* @param algorithm the algorithm name (never null)
* @param key the key (never null)
* @param iv the iv (either null or blockSize bytes long)
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this cipher
*/
abstract void init(boolean decrypting, String algorithm, byte[] key,
byte[] iv) throws InvalidKeyException;
/**
* Gets the initialization vector.
*
* @return the initialization vector
*/
final byte[] getIV() {
return iv;
}
/**
* Resets the iv to its original value.
* This is used when doFinal is called in the Cipher class, so that the
* cipher can be reused (with its original iv).
*/
abstract void reset();
/**
* Performs encryption operation.
*
* <p>The input <code>plain</code>, starting at <code>plainOffset</code>
* and ending at <code>(plainOffset+plainLen-1)</code>, is encrypted.
* The result is stored in <code>cipher</code>, starting at
* <code>cipherOffset</code>.
*
* <p>The subclass that implements Cipher should ensure that
* <code>init</code> has been called before this method is called.
*
* @param plain the input buffer with the data to be encrypted
* @param plainOffset the offset in <code>plain</code>
* @param plainLen the length of the input data
* @param cipher the buffer for the encryption result
* @param cipherOffset the offset in <code>cipher</code>
*/
abstract void encrypt(byte[] plain, int plainOffset, int plainLen,
byte[] cipher, int cipherOffset);
/**
* Performs encryption operation for the last time.
*
* <p>NOTE: For cipher feedback modes which does not perform
* special handling for the last few blocks, this is essentially
* the same as <code>encrypt(...)</code>. Given most modes do
* not do special handling, the default impl for this method is
* to simply call <code>encrypt(...)</code>.
*
* @param plain the input buffer with the data to be encrypted
* @param plainOffset the offset in <code>plain</code>
* @param plainLen the length of the input data
* @param cipher the buffer for the encryption result
* @param cipherOffset the offset in <code>cipher</code>
* @return the number of bytes placed into <code>cipher</code>
*/
int encryptFinal(byte[] plain, int plainOffset, int plainLen,
byte[] cipher, int cipherOffset)
throws IllegalBlockSizeException {
encrypt(plain, plainOffset, plainLen, cipher, cipherOffset);
return plainLen;
}
/**
* Performs decryption operation.
*
* <p>The input <code>cipher</code>, starting at <code>cipherOffset</code>
* and ending at <code>(cipherOffset+cipherLen-1)</code>, is decrypted.
* The result is stored in <code>plain</code>, starting at
* <code>plainOffset</code>.
*
* <p>The subclass that implements Cipher should ensure that
* <code>init</code> has been called before this method is called.
*
* @param cipher the input buffer with the data to be decrypted
* @param cipherOffset the offset in <code>cipher</code>
* @param cipherLen the length of the input data
* @param plain the buffer for the decryption result
* @param plainOffset the offset in <code>plain</code>
*/
abstract void decrypt(byte[] cipher, int cipherOffset, int cipherLen,
byte[] plain, int plainOffset);
/**
* Performs decryption operation for the last time.
*
* <p>NOTE: For cipher feedback modes which does not perform
* special handling for the last few blocks, this is essentially
* the same as <code>encrypt(...)</code>. Given most modes do
* not do special handling, the default impl for this method is
* to simply call <code>decrypt(...)</code>.
*
* @param cipher the input buffer with the data to be decrypted
* @param cipherOffset the offset in <code>cipher</code>
* @param cipherLen the length of the input data
* @param plain the buffer for the decryption result
* @param plainOffset the offset in <code>plain</code>
* @return the number of bytes placed into <code>plain</code>
*/
int decryptFinal(byte[] cipher, int cipherOffset, int cipherLen,
byte[] plain, int plainOffset)
throws IllegalBlockSizeException, AEADBadTagException {
decrypt(cipher, cipherOffset, cipherLen, plain, plainOffset);
return cipherLen;
}
/**
* Continues a multi-part update of the Additional Authentication
* Data (AAD), using a subset of the provided buffer. If this
* cipher is operating in either GCM or CCM mode, all AAD must be
* supplied before beginning operations on the ciphertext (via the
* {@code update} and {@code doFinal} methods).
* <p>
* NOTE: Given most modes do not accept AAD, default impl for this
* method throws IllegalStateException.
*
* @param src the buffer containing the AAD
* @param offset the offset in {@code src} where the AAD input starts
* @param len the number of AAD bytes
*
* @throws IllegalStateException if this cipher is in a wrong state
* (e.g., has not been initialized), does not accept AAD, or if
* operating in either GCM or CCM mode and one of the {@code update}
* methods has already been called for the active
* encryption/decryption operation
* @throws UnsupportedOperationException if this method
* has not been overridden by an implementation
*
* @since 1.8
*/
void updateAAD(byte[] src, int offset, int len) {
throw new IllegalStateException("No AAD accepted");
}
}