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package javax.crypto.spec;
import java.security.spec.AlgorithmParameterSpec;
/**
* This class specifies the parameters used with the
* <a href="http://www.rsa.com/rsalabs/newfaq/q76.html"><i>RC5</i></a>
* algorithm.
* <p>
* The parameters consist of a version number, a rounds count, a word
* size, and optionally an initialization vector (IV) (only in feedback mode).
* <p>
* This class can be used to initialize a <code>Cipher</code> object that
* implements the <i>RC5</i> algorithm as supplied by
* <a href="http://www.rsa.com">RSA Data Security, Inc.</a> (RSA DSI),
* or any parties authorized by RSA DSI.
*/
public class RC5ParameterSpec
implements AlgorithmParameterSpec
{
private int version;
private int rounds;
private int wordSize;
private byte[] iv;
/**
* Constructs a parameter set for RC5 from the given version, number of
* rounds and word size (in bits).
*
* @param version the version.
* @param rounds the number of rounds.
* @param wordSize the word size in bits.
*/
public RC5ParameterSpec(
int version,
int rounds,
int wordSize)
{
this.version = version;
this.rounds = rounds;
this.wordSize = wordSize;
this.iv = null;
}
/**
* Constructs a parameter set for RC5 from the given version, number of
* rounds, word size (in bits), and IV.
* <p>
* Note that the size of the IV (block size) must be twice the word
* size. The bytes that constitute the IV are those between
* <code>iv[0]</code> and <code>iv[2*(wordSize/8)-1]</code> inclusive.
*
* @param version the version.
* @param rounds the number of rounds.
* @param wordSize the word size in bits.
* @param iv the buffer with the IV.
*/
public RC5ParameterSpec(
int version,
int rounds,
int wordSize,
byte[] iv)
{
this(version, rounds, wordSize, iv, 0);
}
/**
* Constructs a parameter set for RC5 from the given version, number of
* rounds, word size (in bits), and IV.
* <p>
* The IV is taken from <code>iv</code>, starting at <code>offset</code> inclusive.
* Note that the size of the IV (block size), starting at
* <code>offset</code> inclusive, must be twice the word size.
* The bytes that constitute the IV are those between
* <code>iv[offset]</code> and <code>iv[offset+2*(wordSize/8)-1]</code>
* inclusive.
*
* @param version the version.
* @param rounds the number of rounds.
* @param wordSize the word size in bits.
* @param iv the buffer with the IV.
* @param offset the offset in <code>iv</code> where the IV starts.
*/
public RC5ParameterSpec(
int version,
int rounds,
int wordSize,
byte[] iv,
int offset)
{
this.version = version;
this.rounds = rounds;
this.wordSize = wordSize;
this.iv = new byte[2 * (wordSize / 8)];
System.arraycopy(iv, offset, this.iv, 0, this.iv.length);
}
/**
* Returns the version.
*
* @return the version.
*/
public int getVersion()
{
return version;
}
/**
* Returns the number of rounds.
*
* @return the number of rounds.
*/
public int getRounds()
{
return rounds;
}
/**
* Returns the word size in bits
*
* @return the word size in bits.
*/
public int getWordSize()
{
return wordSize;
}
/**
* Returns the IV or null if this parameter set does not contain an IV.
*
* @return the IV or null if this parameter set does not contain an IV.
*/
public byte[] getIV()
{
if (iv == null)
{
return null;
}
byte[] tmp = new byte[iv.length];
System.arraycopy(iv, 0, tmp, 0, iv.length);
return tmp;
}
/**
* Tests for equality between the specified object and this
* object. Two RC5ParameterSpec objects are considered equal if their
* version numbers, number of rounds, word sizes, and IVs are equal.
* (Two IV references are considered equal if both are <tt>null</tt>.)
*
* @param obj the object to test for equality with this object.
* @return true if the objects are considered equal, false otherwise.
*/
public boolean equals(
Object obj)
{
if ((obj == null) || !(obj instanceof RC5ParameterSpec))
{
return false;
}
RC5ParameterSpec spec = (RC5ParameterSpec)obj;
if (this.version != spec.version)
{
return false;
}
if (this.rounds != spec.rounds)
{
return false;
}
if (this.wordSize != spec.wordSize)
{
return false;
}
if (iv != null)
{
if (spec.iv == null || spec.iv.length != iv.length)
{
return false;
}
for (int i = 0; i != iv.length; i++)
{
if (iv[i] != spec.iv[i])
{
return false;
}
}
}
else if (spec.iv != null)
{
return false;
}
return true;
}
/**
* Calculates a hash code value for the object.
* Objects that are equal will also have the same hashcode.
*/
public int hashCode()
{
int code = version ^ rounds ^ wordSize;
if (iv != null)
{
for (int i = 0; i != iv.length; i++)
{
code ^= iv[i] << (8 * (i % 4));
}
}
return code;
}
}
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