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package javax.crypto.spec;
import java.security.spec.AlgorithmParameterSpec;
/**
* This class specifies an <i>initialization vector</i> (IV).
* Examples which use IVs are ciphers in feedback mode,
* e.g., DES in CBC mode and RSA ciphers with OAEP encoding
* operation.
*
* @author Jan Luehe
*
* @since 1.4
*/
public class IvParameterSpec implements AlgorithmParameterSpec {
private byte[] iv;
/**
* Creates an IvParameterSpec object using the bytes in <code>iv</code>
* as the IV.
*
* @param iv the buffer with the IV. The contents of the
* buffer are copied to protect against subsequent modification.
* @throws NullPointerException if <code>iv</code> is <code>null</code>
*/
public IvParameterSpec(byte[] iv) {
this(iv, 0, iv.length);
}
/**
* Creates an IvParameterSpec object using the first <code>len</code>
* bytes in <code>iv</code>, beginning at <code>offset</code>
* inclusive, as the IV.
*
* <p> The bytes that constitute the IV are those between
* <code>iv[offset]</code> and <code>iv[offset+len-1]</code> inclusive.
*
* @param iv the buffer with the IV. The first <code>len</code>
* bytes of the buffer beginning at <code>offset</code> inclusive
* are copied to protect against subsequent modification.
* @param offset the offset in <code>iv</code> where the IV
* starts.
* @param len the number of IV bytes.
* @throws IllegalArgumentException if <code>iv</code> is <code>null</code>
* or <code>(iv.length - offset < len)</code>
* @throws ArrayIndexOutOfBoundsException is thrown if <code>offset</code>
* or <code>len</code> index bytes outside the <code>iv</code>.
*/
public IvParameterSpec(byte[] iv, int offset, int len) {
if (iv == null) {
throw new IllegalArgumentException("IV missing");
}
if (iv.length - offset < len) {
throw new IllegalArgumentException
("IV buffer too short for given offset/length combination");
}
if (len < 0) {
throw new ArrayIndexOutOfBoundsException("len is negative");
}
this.iv = new byte[len];
System.arraycopy(iv, offset, this.iv, 0, len);
}
/**
* Returns the initialization vector (IV).
*
* @return the initialization vector (IV). Returns a new array
* each time this method is called.
*/
public byte[] getIV() {
return (byte[])this.iv.clone();
}
}