org.bouncycastle.cms.jcajce.JceCMSContentEncryptorBuilder Maven / Gradle / Ivy

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The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 to JDK 1.8. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.
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package org.bouncycastle.cms.jcajce;

import java.io.OutputStream;
import java.security.AlgorithmParameters;
import java.security.GeneralSecurityException;
import java.security.Provider;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.oiw.OIWObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.cms.CMSException;
import org.bouncycastle.operator.DefaultSecretKeySizeProvider;
import org.bouncycastle.operator.GenericKey;
import org.bouncycastle.operator.OutputEncryptor;
import org.bouncycastle.operator.SecretKeySizeProvider;
import org.bouncycastle.operator.jcajce.JceGenericKey;

/**
 * Builder for the content encryptor in EnvelopedData - used to encrypt the actual transmitted content.
 */
public class JceCMSContentEncryptorBuilder
{
    private static final SecretKeySizeProvider KEY_SIZE_PROVIDER = DefaultSecretKeySizeProvider.INSTANCE;


    private final ASN1ObjectIdentifier encryptionOID;
    private final int                  keySize;

    private EnvelopedDataHelper helper = new EnvelopedDataHelper(new DefaultJcaJceExtHelper());
    private SecureRandom random;
    private AlgorithmParameters algorithmParameters;

    public JceCMSContentEncryptorBuilder(ASN1ObjectIdentifier encryptionOID)
    {
        this(encryptionOID, KEY_SIZE_PROVIDER.getKeySize(encryptionOID));
    }

    public JceCMSContentEncryptorBuilder(ASN1ObjectIdentifier encryptionOID, int keySize)
    {
        this.encryptionOID = encryptionOID;

        int fixedSize = KEY_SIZE_PROVIDER.getKeySize(encryptionOID);

        if (encryptionOID.equals(PKCSObjectIdentifiers.des_EDE3_CBC))
        {
            if (keySize != 168 && keySize != fixedSize)
            {
                throw new IllegalArgumentException("incorrect keySize for encryptionOID passed to builder.");
            }
            this.keySize = 168;
        }
        else if (encryptionOID.equals(OIWObjectIdentifiers.desCBC))
        {
            if (keySize != 56 && keySize != fixedSize)
            {
                throw new IllegalArgumentException("incorrect keySize for encryptionOID passed to builder.");
            }
            this.keySize = 56;
        }
        else
        {
            if (fixedSize > 0 && fixedSize != keySize)
            {
                throw new IllegalArgumentException("incorrect keySize for encryptionOID passed to builder.");
            }
            this.keySize = keySize;
        }
    }

    /**
     * Set the provider to use for content encryption.
     *
     * @param provider the provider object to use for cipher and default parameters creation.
     * @return the current builder instance.
     */
    public JceCMSContentEncryptorBuilder setProvider(Provider provider)
    {
        this.helper = new EnvelopedDataHelper(new ProviderJcaJceExtHelper(provider));

        return this;
    }

    /**
     * Set the provider to use for content encryption (by name)
     *
     * @param providerName the name of the provider to use for cipher and default parameters creation.
     * @return the current builder instance.
     */
    public JceCMSContentEncryptorBuilder setProvider(String providerName)
    {
        this.helper = new EnvelopedDataHelper(new NamedJcaJceExtHelper(providerName));

        return this;
    }

    /**
     * Provide a specified source of randomness to be used for session key and IV/nonce generation.
     *
     * @param random the secure random to use.
     * @return the current builder instance.
     */
    public JceCMSContentEncryptorBuilder setSecureRandom(SecureRandom random)
    {
        this.random = random;

        return this;
    }

    /**
     * Provide a set of algorithm parameters for the content encryption cipher to use.
     *
     * @param algorithmParameters algorithmParameters for content encryption.
     * @return the current builder instance.
     */
    public JceCMSContentEncryptorBuilder setAlgorithmParameters(AlgorithmParameters algorithmParameters)
    {
        this.algorithmParameters = algorithmParameters;

        return this;
    }

    public OutputEncryptor build()
        throws CMSException
    {
        return new CMSOutputEncryptor(encryptionOID, keySize, algorithmParameters, random);
    }

    private class CMSOutputEncryptor
        implements OutputEncryptor
    {
        private SecretKey encKey;
        private AlgorithmIdentifier algorithmIdentifier;
        private Cipher              cipher;

        CMSOutputEncryptor(ASN1ObjectIdentifier encryptionOID, int keySize, AlgorithmParameters params, SecureRandom random)
            throws CMSException
        {
            KeyGenerator keyGen = helper.createKeyGenerator(encryptionOID);

            if (random == null)
            {
                random = new SecureRandom();
            }

            if (keySize < 0)
            {
                keyGen.init(random);
            }
            else
            {
                keyGen.init(keySize, random);
            }

            cipher = helper.createCipher(encryptionOID);
            encKey = keyGen.generateKey();

            if (params == null)
            {
                params = helper.generateParameters(encryptionOID, encKey, random);
            }

            try
            {
                cipher.init(Cipher.ENCRYPT_MODE, encKey, params, random);
            }
            catch (GeneralSecurityException e)
            {
                throw new CMSException("unable to initialize cipher: " + e.getMessage(), e);
            }

            //
            // If params are null we try and second guess on them as some providers don't provide
            // algorithm parameter generation explicity but instead generate them under the hood.
            //
            if (params == null)
            {
                params = cipher.getParameters();
            }

            algorithmIdentifier = helper.getAlgorithmIdentifier(encryptionOID, params);
        }

        public AlgorithmIdentifier getAlgorithmIdentifier()
        {
            return algorithmIdentifier;
        }

        public OutputStream getOutputStream(OutputStream dOut)
        {
            return new CipherOutputStream(dOut, cipher);
        }

        public GenericKey getKey()
        {
            return new JceGenericKey(algorithmIdentifier, encKey);
        }
    }
}