it.scoppelletti.programmerpower.security.spi.IVParameterSpecFactory.java Source code

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Here is the source code for it.scoppelletti.programmerpower.security.spi.IVParameterSpecFactory.java

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/*
 * Copyright (C) 2010 Dario Scoppelletti, <http://www.scoppelletti.it/>.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package it.scoppelletti.programmerpower.security.spi;

import java.util.*;
import java.security.spec.*;
import javax.crypto.spec.*;
import org.apache.commons.codec.*;
import org.apache.commons.codec.binary.*;
import it.scoppelletti.programmerpower.*;
import it.scoppelletti.programmerpower.security.*;
import it.scoppelletti.programmerpower.types.*;

/**
 * Classe di factory del vettore di inizializzazione {@code IV} per una
 * modalit&agrave; di feedback. 
 *
 * <P><TABLE WIDTH="100%" BORDER="1" CELLPADDING="5">
 * <THEAD>
 * <TR>
 *     <TH>Propriet&agrave;</TH>
 *     <TH>Descrizione</TH>     
 * </TR>
 * </THEAD>
 * <TBODY>     
 * <TR>
 *      <TD>{@code iv}</TD>
 *      <TD>Vettore di inizializzazione in formato esadecimale.</TD>
 * </TR>  
 * </TBODY>
 * </TABLE></P>
 * 
 * @see   it.scoppelletti.programmerpower.security.CryptoUtils#getCipher
 * @see   <A HREF="{@docRoot}/it/scoppelletti/programmerpower/security/CryptoUtils.html#idMode">Modalit&agrave;
 *        degli algoritmi di cifratura</A>  
 * @since 1.0.0
 */
public final class IVParameterSpecFactory implements AlgorithmParameterSpecFactory {

    /**
     * Nome della propriet&agrave; sulla quale deve essere impostato il vettore
     * di inizializzazione. Il valore della costante &egrave;
     * <CODE>{@value}</CODE>.
     */
    public static final String PROP_IV = "iv";

    /**
     * Costruttore.
     */
    public IVParameterSpecFactory() {
    }

    public AlgorithmParameterSpec newInstance(Properties props, String prefix) {
        String name, value;
        byte[] iv;
        AlgorithmParameterSpec param;

        name = Strings.concat(prefix, IVParameterSpecFactory.PROP_IV);
        value = props.getProperty(name);
        if (Strings.isNullOrEmpty(value)) {
            throw new ArgumentNullException(name);
        }

        try {
            iv = Hex.decodeHex(value.toCharArray());
        } catch (DecoderException ex) {
            throw SecurityUtils.toSecurityException(ex);
        }

        param = new IvParameterSpec(iv);

        return param;
    }
}