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package javax.crypto.spec;

import java.security.spec.AlgorithmParameterSpec;


This class specifies the parameters used with the
RC2
algorithm.

 The parameters consist of an effective key size and optionally
an 8-byte initialization vector (IV) (only in feedback mode).

 This class can be used to initialize a Cipher object that implements the RC2 algorithm.

Author:Jan Luehe
Since:1.4
/**
 * This class specifies the parameters used with the
 * <a href="http://www.ietf.org/rfc/rfc2268.txt"><i>RC2</i></a>
 * algorithm.
 *
 * <p> The parameters consist of an effective key size and optionally
 * an 8-byte initialization vector (IV) (only in feedback mode).
 *
 * <p> This class can be used to initialize a {@code Cipher} object that
 * implements the <i>RC2</i> algorithm.
 *
 * @author Jan Luehe
 *
 * @since 1.4
 */
public class RC2ParameterSpec implements AlgorithmParameterSpec {

    private byte[] iv = null;
    private int effectiveKeyBits;

    
Constructs a parameter set for RC2 from the given effective key size
(in bits).

Params:
  • effectiveKeyBits – the effective key size in bits.
/**
     * Constructs a parameter set for RC2 from the given effective key size
     * (in bits).
     *
     * @param effectiveKeyBits the effective key size in bits.
     */
    public RC2ParameterSpec(int effectiveKeyBits) {
        this.effectiveKeyBits = effectiveKeyBits;
    }

    
Constructs a parameter set for RC2 from the given effective key size
(in bits) and an 8-byte IV.

 The bytes that constitute the IV are those between iv[0] and iv[7] inclusive. 
Params:
  • effectiveKeyBits – the effective key size in bits.
  • iv – the buffer with the 8-byte IV. The first 8 bytes of
the buffer are copied to protect against subsequent modification.
Throws:
/**
     * Constructs a parameter set for RC2 from the given effective key size
     * (in bits) and an 8-byte IV.
     *
     * <p> The bytes that constitute the IV are those between
     * {@code iv[0]} and {@code iv[7]} inclusive.
     *
     * @param effectiveKeyBits the effective key size in bits.
     * @param iv the buffer with the 8-byte IV. The first 8 bytes of
     * the buffer are copied to protect against subsequent modification.
     * @exception IllegalArgumentException if {@code iv} is null.
     */
    public RC2ParameterSpec(int effectiveKeyBits, byte[] iv) {
        this(effectiveKeyBits, iv, 0);
    }

    
Constructs a parameter set for RC2 from the given effective key size
(in bits) and IV.

 The IV is taken from iv, starting at offset inclusive. The bytes that constitute the IV are those between iv[offset] and iv[offset+7] inclusive. 
Params:
  • effectiveKeyBits – the effective key size in bits.
  • iv – the buffer with the IV. The first 8 bytes of the buffer beginning at offset inclusive are copied to protect against subsequent modification.
  • offset – the offset in iv where the 8-byte IV starts.
Throws:
/**
     * Constructs a parameter set for RC2 from the given effective key size
     * (in bits) and IV.
     *
     * <p> The IV is taken from {@code iv}, starting at
     * {@code offset} inclusive.
     * The bytes that constitute the IV are those between
     * {@code iv[offset]} and {@code iv[offset+7]} inclusive.
     *
     * @param effectiveKeyBits the effective key size in bits.
     * @param iv the buffer with the IV. The first 8 bytes
     * of the buffer beginning at {@code offset} inclusive
     * are copied to protect against subsequent modification.
     * @param offset the offset in {@code iv} where the 8-byte IV
     * starts.
     * @exception IllegalArgumentException if {@code iv} is null.
     */
    public RC2ParameterSpec(int effectiveKeyBits, byte[] iv, int offset) {
        this.effectiveKeyBits = effectiveKeyBits;
        if (iv == null) throw new IllegalArgumentException("IV missing");
        int blockSize = 8;
        if (iv.length - offset < blockSize) {
            throw new IllegalArgumentException("IV too short");
        }
        this.iv = new byte[blockSize];
        System.arraycopy(iv, offset, this.iv, 0, blockSize);
    }

    
Returns the effective key size in bits.

Returns:the effective key size in bits.
/**
     * Returns the effective key size in bits.
     *
     * @return the effective key size in bits.
     */
    public int getEffectiveKeyBits() {
        return this.effectiveKeyBits;
    }

    
Returns the IV or null if this parameter set does not contain an IV.

Returns:the IV or null if this parameter set does not contain an IV.
Returns a new array each time this method is called.
/**
     * 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.
     * Returns a new array each time this method is called.
     */
    public byte[] getIV() {
        return (iv == null? null:iv.clone());
    }

    
Tests for equality between the specified object and this object. Two RC2ParameterSpec objects are considered equal if their effective key sizes and IVs are equal. (Two IV references are considered equal if both are null.) 
Params:
  • obj – the object to test for equality with this object.
Returns:true if the objects are considered equal, false if obj is null or otherwise.
/**
     * Tests for equality between the specified object and this
     * object. Two RC2ParameterSpec objects are considered equal if their
     * effective key sizes and IVs are equal.
     * (Two IV references are considered equal if both are {@code null}.)
     *
     * @param obj the object to test for equality with this object.
     *
     * @return true if the objects are considered equal, false if
     * {@code obj} is null or otherwise.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof RC2ParameterSpec)) {
            return false;
        }
        RC2ParameterSpec other = (RC2ParameterSpec) obj;

        return ((effectiveKeyBits == other.effectiveKeyBits) &&
                java.util.Arrays.equals(iv, other.iv));
    }

    
Calculates a hash code value for the object.
Objects that are equal will also have the same hashcode.

/**
     * Calculates a hash code value for the object.
     * Objects that are equal will also have the same hashcode.
     */
    public int hashCode() {
        int retval = 0;
        if (iv != null) {
            for (int i = 1; i < iv.length; i++) {
                retval += iv[i] * i;
            }
        }
        return (retval += effectiveKeyBits);
    }
}