org.bouncycastle.openpgp.operator.jcajce.JcePBEDataDecryptorFactoryBuilder.java Source code

Introduction

Here is the source code for org.bouncycastle.openpgp.operator.jcajce.JcePBEDataDecryptorFactoryBuilder.java

Source

package org.bouncycastle.openpgp.operator.jcajce;

import java.security.Provider;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.jcajce.util.DefaultJcaJceHelper;
import org.bouncycastle.jcajce.util.NamedJcaJceHelper;
import org.bouncycastle.jcajce.util.ProviderJcaJceHelper;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPUtil;
import org.bouncycastle.openpgp.operator.PBEDataDecryptorFactory;
import org.bouncycastle.openpgp.operator.PGPDataDecryptor;
import org.bouncycastle.openpgp.operator.PGPDigestCalculatorProvider;

/**
 * Builder for {@link PBEDataDecryptorFactory} instances that obtain cryptographic primitives using
 * the JCE API.
 */
public class JcePBEDataDecryptorFactoryBuilder {
    private OperatorHelper helper = new OperatorHelper(new DefaultJcaJceHelper());
    private PGPDigestCalculatorProvider calculatorProvider;

    /**
     * Base constructor.
     *
     * @param calculatorProvider   a digest calculator provider to provide calculators to support the key generation calculation required.
     */
    public JcePBEDataDecryptorFactoryBuilder(PGPDigestCalculatorProvider calculatorProvider) {
        this.calculatorProvider = calculatorProvider;
    }

    /**
     * Set the provider object to use for creating cryptographic primitives in the resulting factory the builder produces.
     *
     * @param provider  provider object for cryptographic primitives.
     * @return  the current builder.
     */
    public JcePBEDataDecryptorFactoryBuilder setProvider(Provider provider) {
        this.helper = new OperatorHelper(new ProviderJcaJceHelper(provider));

        return this;
    }

    /**
     * Set the provider name to use for creating cryptographic primitives in the resulting factory the builder produces.
     *
     * @param providerName  the name of the provider to reference for cryptographic primitives.
     * @return  the current builder.
     */
    public JcePBEDataDecryptorFactoryBuilder setProvider(String providerName) {
        this.helper = new OperatorHelper(new NamedJcaJceHelper(providerName));

        return this;
    }

    /**
     * Construct a {@link PBEDataDecryptorFactory} to use to decrypt PBE encrypted data.
     *
     * @param passPhrase the pass phrase to use to generate keys in the resulting factory.
     * @return a decryptor factory that can be used to generate PBE keys.
     */
    public PBEDataDecryptorFactory build(char[] passPhrase) {
        return new PBEDataDecryptorFactory(passPhrase, calculatorProvider) {
            public byte[] recoverSessionData(int keyAlgorithm, byte[] key, byte[] secKeyData) throws PGPException {
                try {
                    if (secKeyData != null && secKeyData.length > 0) {
                        String cipherName = PGPUtil.getSymmetricCipherName(keyAlgorithm);
                        Cipher keyCipher = helper.createCipher(cipherName + "/CFB/NoPadding");

                        keyCipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, cipherName),
                                new IvParameterSpec(new byte[keyCipher.getBlockSize()]));

                        return keyCipher.doFinal(secKeyData);
                    } else {
                        byte[] keyBytes = new byte[key.length + 1];

                        keyBytes[0] = (byte) keyAlgorithm;
                        System.arraycopy(key, 0, keyBytes, 1, key.length);

                        return keyBytes;
                    }
                } catch (Exception e) {
                    throw new PGPException("Exception recovering session info", e);
                }
            }

            public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
                    throws PGPException {
                return helper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
            }
        };
    }
}