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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.4.
package org.bouncycastle.pqc.jcajce.provider.util;
import java.io.ByteArrayOutputStream;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.InvalidParameterException;
import java.security.Key;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.ShortBufferException;
import org.bouncycastle.crypto.CryptoServicesRegistrar;
/**
* The AsymmetricBlockCipher class extends CipherSpiExt.
* NOTE: Some Ciphers are using Padding. OneAndZeroesPadding is used as default
* padding. However padding can still be specified, but mode is not supported;
* if you try to instantiate the cipher with something else than "NONE" as mode
* NoSuchAlgorithmException is thrown.
*/
public abstract class AsymmetricBlockCipher
extends CipherSpiExt
{
/**
* ParameterSpec used with this cipher
*/
protected AlgorithmParameterSpec paramSpec;
/**
* Internal buffer
*/
protected ByteArrayOutputStream buf;
/**
* The maximum number of bytes the cipher can decrypt.
*/
protected int maxPlainTextSize;
/**
* The maximum number of bytes the cipher can encrypt.
*/
protected int cipherTextSize;
/**
* The AsymmetricBlockCipher() constructor
*/
public AsymmetricBlockCipher()
{
buf = new ByteArrayOutputStream();
}
/**
* Return the block size (in bytes). Note: although the ciphers extending
* this class are not block ciphers, the method was adopted to return the
* maximal plaintext and ciphertext sizes for non hybrid ciphers. If the
* cipher is hybrid, it returns 0.
*
* @return if the cipher is not a hybrid one the max plain/cipher text size
* is returned, otherwise 0 is returned
*/
public final int getBlockSize()
{
return opMode == ENCRYPT_MODE ? maxPlainTextSize : cipherTextSize;
}
/**
* @return null since no initialization vector is used.
*/
public final byte[] getIV()
{
return null;
}
/**
* Return the length in bytes that an output buffer would need to be in
* order to hold the result of the next update or doFinal operation, given
* the input length inLen (in bytes). This call takes into
* account any unprocessed (buffered) data from a previous update call, and
* padding. The actual output length of the next update() or doFinal() call
* may be smaller than the length returned by this method.
*
* If the input length plus the length of the buffered data exceeds the
* maximum length, 0 is returned.
*
* @param inLen the length of the input
* @return the length of the ciphertext or 0 if the input is too
* long.
*/
public final int getOutputSize(int inLen)
{
int totalLen = inLen + buf.size();
int maxLen = getBlockSize();
if (totalLen > maxLen)
{
// the length of the input exceeds the maximal supported length
return 0;
}
return opMode == ENCRYPT_MODE ? cipherTextSize : maxPlainTextSize;
}
/**
* Returns the parameters used with this cipher.
*
* The returned parameters may be the same that were used to initialize this
* cipher, or may contain the default set of parameters or a set of randomly
* generated parameters used by the underlying cipher implementation
* (provided that the underlying cipher implementation uses a default set of
* parameters or creates new parameters if it needs parameters but was not
* initialized with any).
*
*
* @return the parameters used with this cipher, or null if this cipher does
* not use any parameters.
*/
public final AlgorithmParameterSpec getParameters()
{
return paramSpec;
}
/**
* Initializes the cipher for encryption by forwarding it to
* initEncrypt(Key, FlexiSecureRandom).
*
* If this cipher requires any algorithm parameters that cannot be derived
* from the given key, the underlying cipher implementation is supposed to
* generate the required parameters itself (using provider-specific default
* or random values) if it is being initialized for encryption, and raise an
* InvalidKeyException if it is being initialized for decryption. The
* generated parameters can be retrieved using engineGetParameters or
* engineGetIV (if the parameter is an IV).
*
* @param key the encryption or decryption key.
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher.
*/
public final void initEncrypt(Key key)
throws InvalidKeyException
{
try
{
initEncrypt(key, null, CryptoServicesRegistrar.getSecureRandom());
}
catch (InvalidAlgorithmParameterException e)
{
throw new InvalidParameterException(
"This cipher needs algorithm parameters for initialization (cannot be null).");
}
}
/**
* Initialize this cipher for encryption by forwarding it to
* initEncrypt(Key, FlexiSecureRandom, AlgorithmParameterSpec).
*
* If this cipher requires any algorithm parameters that cannot be derived
* from the given key, the underlying cipher implementation is supposed to
* generate the required parameters itself (using provider-specific default
* or random values) if it is being initialized for encryption, and raise an
* InvalidKeyException if it is being initialized for decryption. The
* generated parameters can be retrieved using engineGetParameters or
* engineGetIV (if the parameter is an IV).
*
* @param key the encryption or decryption key.
* @param random the source of randomness.
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher.
*/
public final void initEncrypt(Key key, SecureRandom random)
throws InvalidKeyException
{
try
{
initEncrypt(key, null, random);
}
catch (InvalidAlgorithmParameterException iape)
{
throw new InvalidParameterException(
"This cipher needs algorithm parameters for initialization (cannot be null).");
}
}
/**
* Initializes the cipher for encryption by forwarding it to
* initEncrypt(Key, FlexiSecureRandom, AlgorithmParameterSpec).
*
* @param key the encryption or decryption key.
* @param params the algorithm parameters.
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher.
* @throws InvalidAlgorithmParameterException if the given algortihm parameters are inappropriate for
* this cipher, or if this cipher is being initialized for
* decryption and requires algorithm parameters and params
* is null.
*/
public final void initEncrypt(Key key, AlgorithmParameterSpec params)
throws InvalidKeyException, InvalidAlgorithmParameterException
{
initEncrypt(key, params, CryptoServicesRegistrar.getSecureRandom());
}
/**
* This method initializes the AsymmetricBlockCipher with a certain key for
* data encryption.
*
* If this cipher (including its underlying feedback or padding scheme)
* requires any random bytes (e.g., for parameter generation), it will get
* them from random.
*
* Note that when a Cipher object is initialized, it loses all
* previously-acquired state. In other words, initializing a Cipher is
* equivalent to creating a new instance of that Cipher and initializing it
*
*
* @param key the key which has to be used to encrypt data.
* @param secureRandom the source of randomness.
* @param params the algorithm parameters.
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher
* @throws InvalidAlgorithmParameterException if the given algorithm parameters are inappropriate for
* this cipher, or if this cipher is being initialized for
* decryption and requires algorithm parameters and params
* is null.
*/
public final void initEncrypt(Key key, AlgorithmParameterSpec params,
SecureRandom secureRandom)
throws InvalidKeyException,
InvalidAlgorithmParameterException
{
opMode = ENCRYPT_MODE;
initCipherEncrypt(key, params, secureRandom);
}
/**
* Initialize the cipher for decryption by forwarding it to
* {@link #initDecrypt(Key, AlgorithmParameterSpec)}.
*
* If this cipher requires any algorithm parameters that cannot be derived
* from the given key, the underlying cipher implementation is supposed to
* generate the required parameters itself (using provider-specific default
* or random values) if it is being initialized for encryption, and raise an
* InvalidKeyException if it is being initialized for decryption. The
* generated parameters can be retrieved using engineGetParameters or
* engineGetIV (if the parameter is an IV).
*
* @param key the encryption or decryption key.
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher.
*/
public final void initDecrypt(Key key)
throws InvalidKeyException
{
try
{
initDecrypt(key, null);
}
catch (InvalidAlgorithmParameterException iape)
{
throw new InvalidParameterException(
"This cipher needs algorithm parameters for initialization (cannot be null).");
}
}
/**
* This method initializes the AsymmetricBlockCipher with a certain key for
* data decryption.
*
* If this cipher (including its underlying feedback or padding scheme)
* requires any random bytes (e.g., for parameter generation), it will get
* them from random.
*
* Note that when a Cipher object is initialized, it loses all
* previously-acquired state. In other words, initializing a Cipher is
* equivalent to creating a new instance of that Cipher and initializing it
*
*
* @param key the key which has to be used to decrypt data.
* @param params the algorithm parameters.
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher
* @throws InvalidAlgorithmParameterException if the given algorithm parameters are inappropriate for
* this cipher, or if this cipher is being initialized for
* decryption and requires algorithm parameters and params
* is null.
*/
public final void initDecrypt(Key key, AlgorithmParameterSpec params)
throws InvalidKeyException, InvalidAlgorithmParameterException
{
opMode = DECRYPT_MODE;
initCipherDecrypt(key, params);
}
/**
* Continue a multiple-part encryption or decryption operation. This method
* just writes the input into an internal buffer.
*
* @param input byte array containing the next part of the input
* @param inOff index in the array where the input starts
* @param inLen length of the input
* @return a new buffer with the result (always empty)
*/
public final byte[] update(byte[] input, int inOff, int inLen)
{
if (inLen != 0)
{
buf.write(input, inOff, inLen);
}
return new byte[0];
}
/**
* Continue a multiple-part encryption or decryption operation (depending on
* how this cipher was initialized), processing another data part.
*
* @param input the input buffer
* @param inOff the offset where the input starts
* @param inLen the input length
* @param output the output buffer
* @param outOff the offset where the result is stored
* @return the length of the output (always 0)
*/
public final int update(byte[] input, int inOff, int inLen, byte[] output,
int outOff)
{
update(input, inOff, inLen);
return 0;
}
/**
* Finish a multiple-part encryption or decryption operation (depending on
* how this cipher was initialized).
*
* @param input the input buffer
* @param inOff the offset where the input starts
* @param inLen the input length
* @return a new buffer with the result
* @throws IllegalBlockSizeException if the plaintext or ciphertext size is too large.
* @throws BadPaddingException if the ciphertext is invalid.
*/
public final byte[] doFinal(byte[] input, int inOff, int inLen)
throws IllegalBlockSizeException, BadPaddingException
{
checkLength(inLen);
update(input, inOff, inLen);
byte[] mBytes = buf.toByteArray();
buf.reset();
switch (opMode)
{
case ENCRYPT_MODE:
return messageEncrypt(mBytes);
case DECRYPT_MODE:
return messageDecrypt(mBytes);
default:
return null;
}
}
/**
* Finish a multiple-part encryption or decryption operation (depending on
* how this cipher was initialized).
*
* @param input the input buffer
* @param inOff the offset where the input starts
* @param inLen the input length
* @param output the buffer for the result
* @param outOff the offset where the result is stored
* @return the output length
* @throws ShortBufferException if the output buffer is too small to hold the result.
* @throws IllegalBlockSizeException if the plaintext or ciphertext size is too large.
* @throws BadPaddingException if the ciphertext is invalid.
*/
public final int doFinal(byte[] input, int inOff, int inLen, byte[] output,
int outOff)
throws ShortBufferException, IllegalBlockSizeException,
BadPaddingException
{
if (output.length < getOutputSize(inLen))
{
throw new ShortBufferException("Output buffer too short.");
}
byte[] out = doFinal(input, inOff, inLen);
System.arraycopy(out, 0, output, outOff, out.length);
return out.length;
}
/**
* Since asymmetric block ciphers do not support modes, this method does
* nothing.
*
* @param modeName the cipher mode (unused)
*/
protected final void setMode(String modeName)
{
// empty
}
/**
* Since asymmetric block ciphers do not support padding, this method does
* nothing.
*
* @param paddingName the name of the padding scheme (not used)
*/
protected final void setPadding(String paddingName)
{
// empty
}
/**
* Check if the message length plus the length of the input length can be
* en/decrypted. This method uses the specific values
* {@link #maxPlainTextSize} and {@link #cipherTextSize} which are set by
* the implementations. If the input length plus the length of the internal
* buffer is greater than {@link #maxPlainTextSize} for encryption or not
* equal to {@link #cipherTextSize} for decryption, an
* {@link IllegalBlockSizeException} will be thrown.
*
* @param inLen length of the input to check
* @throws IllegalBlockSizeException if the input length is invalid.
*/
protected void checkLength(int inLen)
throws IllegalBlockSizeException
{
int inLength = inLen + buf.size();
if (opMode == ENCRYPT_MODE)
{
if (inLength > maxPlainTextSize)
{
throw new IllegalBlockSizeException(
"The length of the plaintext (" + inLength
+ " bytes) is not supported by "
+ "the cipher (max. " + maxPlainTextSize
+ " bytes).");
}
}
else if (opMode == DECRYPT_MODE)
{
if (inLength != cipherTextSize)
{
throw new IllegalBlockSizeException(
"Illegal ciphertext length (expected " + cipherTextSize
+ " bytes, was " + inLength + " bytes).");
}
}
}
/**
* Initialize the AsymmetricBlockCipher with a certain key for data
* encryption.
*
* @param key the key which has to be used to encrypt data
* @param params the algorithm parameters
* @param sr the source of randomness
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher.
* @throws InvalidAlgorithmParameterException if the given parameters are inappropriate for
* initializing this cipher.
*/
protected abstract void initCipherEncrypt(Key key,
AlgorithmParameterSpec params, SecureRandom sr)
throws InvalidKeyException, InvalidAlgorithmParameterException;
/**
* Initialize the AsymmetricBlockCipher with a certain key for data
* encryption.
*
* @param key the key which has to be used to decrypt data
* @param params the algorithm parameters
* @throws InvalidKeyException if the given key is inappropriate for initializing this
* cipher
* @throws InvalidAlgorithmParameterException if the given parameters are inappropriate for
* initializing this cipher.
*/
protected abstract void initCipherDecrypt(Key key,
AlgorithmParameterSpec params)
throws InvalidKeyException,
InvalidAlgorithmParameterException;
/**
* Encrypt the message stored in input. The method should also perform an
* additional length check.
*
* @param input the message to be encrypted (usually the message length is
* less than or equal to maxPlainTextSize)
* @return the encrypted message (it has length equal to maxCipherTextSize_)
* @throws IllegalBlockSizeException if the input is inappropriate for this cipher.
* @throws BadPaddingException if the input format is invalid.
*/
protected abstract byte[] messageEncrypt(byte[] input)
throws IllegalBlockSizeException, BadPaddingException;
/**
* Decrypt the ciphertext stored in input. The method should also perform an
* additional length check.
*
* @param input the ciphertext to be decrypted (the ciphertext length is
* less than or equal to maxCipherTextSize)
* @return the decrypted message
* @throws IllegalBlockSizeException if the input is inappropriate for this cipher.
* @throws BadPaddingException if the input format is invalid.
*/
protected abstract byte[] messageDecrypt(byte[] input)
throws IllegalBlockSizeException, BadPaddingException;
}
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