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25 
26 package javax.crypto.spec;
27 
28 import java.security.spec.AlgorithmParameterSpec;
29 
30 /**
31  * This class specifies the parameters used with the
32  * <a href="http://www.ietf.org/rfc/rfc2268.txt"><i>RC2</i></a>
33  * algorithm.
34  *
35  * <p> The parameters consist of an effective key size and optionally
36  * an 8-byte initialization vector (IV) (only in feedback mode).
37  *
38  * <p> This class can be used to initialize a <code>Cipher</code> object that
39  * implements the <i>RC2</i> algorithm.
40  *
41  * @author Jan Luehe
42  *
43  * @since 1.4
44  */
45 public class RC2ParameterSpec implements AlgorithmParameterSpec {
46 
47     private byte[] iv = null;
48     private int effectiveKeyBits;
49 
50     /**
51      * Constructs a parameter set for RC2 from the given effective key size
52      * (in bits).
53      *
54      * @param effectiveKeyBits the effective key size in bits.
55      */
RC2ParameterSpec(int effectiveKeyBits)56     public RC2ParameterSpec(int effectiveKeyBits) {
57         this.effectiveKeyBits = effectiveKeyBits;
58     }
59 
60     /**
61      * Constructs a parameter set for RC2 from the given effective key size
62      * (in bits) and an 8-byte IV.
63      *
64      * <p> The bytes that constitute the IV are those between
65      * <code>iv[0]</code> and <code>iv[7]</code> inclusive.
66      *
67      * @param effectiveKeyBits the effective key size in bits.
68      * @param iv the buffer with the 8-byte IV. The first 8 bytes of
69      * the buffer are copied to protect against subsequent modification.
70      * @exception IllegalArgumentException if <code>iv</code> is null.
71      */
RC2ParameterSpec(int effectiveKeyBits, byte[] iv)72     public RC2ParameterSpec(int effectiveKeyBits, byte[] iv) {
73         this(effectiveKeyBits, iv, 0);
74     }
75 
76     /**
77      * Constructs a parameter set for RC2 from the given effective key size
78      * (in bits) and IV.
79      *
80      * <p> The IV is taken from <code>iv</code>, starting at
81      * <code>offset</code> inclusive.
82      * The bytes that constitute the IV are those between
83      * <code>iv[offset]</code> and <code>iv[offset+7]</code> inclusive.
84      *
85      * @param effectiveKeyBits the effective key size in bits.
86      * @param iv the buffer with the IV. The first 8 bytes
87      * of the buffer beginning at <code>offset</code> inclusive
88      * are copied to protect against subsequent modification.
89      * @param offset the offset in <code>iv</code> where the 8-byte IV
90      * starts.
91      * @exception IllegalArgumentException if <code>iv</code> is null.
92      */
RC2ParameterSpec(int effectiveKeyBits, byte[] iv, int offset)93     public RC2ParameterSpec(int effectiveKeyBits, byte[] iv, int offset) {
94         this.effectiveKeyBits = effectiveKeyBits;
95         if (iv == null) throw new IllegalArgumentException("IV missing");
96         int blockSize = 8;
97         if (iv.length - offset < blockSize) {
98             throw new IllegalArgumentException("IV too short");
99         }
100         this.iv = new byte[blockSize];
101         System.arraycopy(iv, offset, this.iv, 0, blockSize);
102     }
103 
104     /**
105      * Returns the effective key size in bits.
106      *
107      * @return the effective key size in bits.
108      */
getEffectiveKeyBits()109     public int getEffectiveKeyBits() {
110         return this.effectiveKeyBits;
111     }
112 
113     /**
114      * Returns the IV or null if this parameter set does not contain an IV.
115      *
116      * @return the IV or null if this parameter set does not contain an IV.
117      * Returns a new array each time this method is called.
118      */
getIV()119     public byte[] getIV() {
120         return (iv == null? null:iv.clone());
121     }
122 
123    /**
124      * Tests for equality between the specified object and this
125      * object. Two RC2ParameterSpec objects are considered equal if their
126      * effective key sizes and IVs are equal.
127      * (Two IV references are considered equal if both are <tt>null</tt>.)
128      *
129      * @param obj the object to test for equality with this object.
130      *
131      * @return true if the objects are considered equal, false if
132      * <code>obj</code> is null or otherwise.
133      */
equals(Object obj)134     public boolean equals(Object obj) {
135         if (obj == this) {
136             return true;
137         }
138         if (!(obj instanceof RC2ParameterSpec)) {
139             return false;
140         }
141         RC2ParameterSpec other = (RC2ParameterSpec) obj;
142 
143         return ((effectiveKeyBits == other.effectiveKeyBits) &&
144                 java.util.Arrays.equals(iv, other.iv));
145     }
146 
147     /**
148      * Calculates a hash code value for the object.
149      * Objects that are equal will also have the same hashcode.
150      */
hashCode()151     public int hashCode() {
152         int retval = 0;
153         if (iv != null) {
154             for (int i = 1; i < iv.length; i++) {
155                 retval += iv[i] * i;
156             }
157         }
158         return (retval += effectiveKeyBits);
159     }
160 }
161