DecryptOpenSSLPass.java

/*
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 * 
 * Copyright (c) 2005-2025 Link.it srl (https://link.it). 
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3, as published by
 * the Free Software Foundation.
 *
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
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package org.openspcoop2.utils.security;

import java.util.Arrays;

import javax.crypto.spec.SecretKeySpec;

import org.openspcoop2.utils.UtilsException;
import org.openspcoop2.utils.certificate.SymmetricKeyUtils;
import org.openspcoop2.utils.io.Base64Utilities;
import org.openspcoop2.utils.io.HexBinaryUtilities;

/** 
 * Encrypt
 *
 * @author Poli Andrea (apoli@link.it)
 * @author $Author$
 * @version $Rev$, $Date$
 */
public class DecryptOpenSSLPass extends AbstractCipher {

    /**
      * 
      * Openssl encrypts data using the following steps:
      * 1. bytes = cipherText
      * 2. salt = bytes[8,16)
      * 3. key = messageDigest("sha256", password+salt)
      * 4. iv = messageDigest(key+password+salt)[0,16)
      * 5. plainText = decrypt("aes256cbc", key, iv, bytes[16..end])
    */

    public static CipherInfo buildCipherInfo(byte[] cipherBytes, String password, String digestAlgoParam, OpenSSLEncryptionMode mode) throws UtilsException {
        
        CipherInfo cipherInfo = new CipherInfo();
        
        cipherInfo.setSalt(buildSalt(cipherBytes));
        
        cipherInfo.setEncodedKey(EncryptOpenSSLPass.buildSecretKey(password, cipherInfo.getSalt(), digestAlgoParam, mode));
        cipherInfo.setKey(new SecretKeySpec(cipherInfo.getEncodedKey(), SymmetricKeyUtils.ALGO_AES));
        
        cipherInfo.setIv(EncryptOpenSSLPass.buildIV(password, cipherInfo.getSalt(), cipherInfo.getEncodedKey(), digestAlgoParam));
        cipherInfo.setIvParameterSpec(EncryptOpenSSLPass.convertTo(cipherInfo.getIv()));
        
        return cipherInfo;
    }
    static byte[] buildSalt(byte[] cipherBytes) throws UtilsException {
        try {                
            return Arrays.copyOfRange(cipherBytes, 8, 16);
        }catch(Exception e) {
            throw new UtilsException(e.getMessage(),e);
        }
    }
    
    public static byte[] extractCipherBytes(byte[] data) {
        return Arrays.copyOfRange(
                data, 16, data.length);
    }
    
    
    private OpenSSLEncryptionMode mode;
    private String password;
    
    public DecryptOpenSSLPass(String password) {
        this(password, null);
    }
    public DecryptOpenSSLPass(String password, OpenSSLEncryptionMode modeParam) {
        super(javax.crypto.Cipher.DECRYPT_MODE);
        this.mode = modeParam!=null ? modeParam : OpenSSLEncryptionMode.AES_256_CBC;
        this.password = password;
    }


    public byte[] decrypt(byte[] data) throws UtilsException{
        CipherInfo cipherInfo = buildCipherInfo(data, this.password, null, this.mode);
        this.key = cipherInfo.getKey();
        this.ivParameterSpec = cipherInfo.getIvParameterSpec();
        byte[] cipherBytes = extractCipherBytes(data);
        return super.process(cipherBytes, EncryptOpenSSLPass.getAlgorithm(this.mode));
    }
    
    public byte[] decryptBase64(byte[] data) throws UtilsException{
        return this.decrypt(Base64Utilities.decode(data));
    }
    
    public byte[] decryptBase64(String data) throws UtilsException{
        return this.decrypt(Base64Utilities.decode(data));
    }
    
    public byte[] decryptHexBinary(char[] data) throws UtilsException{
        return this.decrypt(HexBinaryUtilities.decode(data));
    }
    
    public byte[] decryptHexBinary(String data) throws UtilsException{
        return this.decrypt(HexBinaryUtilities.decode(data));
    }
    
    
    @Override
    public void initIV(String algorithm) throws UtilsException{
        // NOP
        // Non deve fare nulla questa chiamata, viene gestita dalla funzione sopra l'IV
    }
}