org.bouncycastle.its.jcajce.JcaETSIDataDecryptor Maven / Gradle / Ivy

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The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, S/MIME and certificate generation. The APIs are designed primarily to be used in conjunction with the BC FIPS provider. The APIs may also be used with other providers although if being used in a FIPS context it is the responsibility of the user to ensure that any other providers used are FIPS certified and used appropriately.

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package org.bouncycastle.its.jcajce;

import java.security.PrivateKey;
import java.security.Provider;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;

import org.bouncycastle.its.operator.ETSIDataDecryptor;
import org.bouncycastle.jcajce.util.JcaJceHelper;
import org.bouncycastle.jcajce.util.NamedJcaJceHelper;
import org.bouncycastle.jcajce.util.ProviderJcaJceHelper;
import org.bouncycastle.util.Arrays;


public class JcaETSIDataDecryptor
    implements ETSIDataDecryptor
{
    private final PrivateKey privateKey;
    private final JcaJceHelper helper;
    private final byte[] recipientHash;

    private SecretKey secretKey = null;

    JcaETSIDataDecryptor(PrivateKey recipientInfo, byte[] recipientHash, JcaJceHelper provider)
    {
        this.privateKey = recipientInfo;
        this.helper = provider;
        this.recipientHash = recipientHash;
    }

    public byte[] decrypt(byte[] wrappedKey, byte[] content, byte[] nonce)
    {
        try
        {
            Cipher etsiKem = helper.createCipher("ETSIKEMwithSHA256");
            etsiKem.init(Cipher.UNWRAP_MODE, privateKey, new IESKEMParameterSpec(recipientHash));

            // [ephemeral public key][encrypted key][tag]
            secretKey = (SecretKey)etsiKem.unwrap(wrappedKey, "AES", Cipher.SECRET_KEY);

            Cipher ccm = helper.createCipher("CCM");
            ccm.init(Cipher.DECRYPT_MODE, secretKey, ClassUtil.getGCMSpec(nonce, 128));
            return ccm.doFinal(content);
        }
        catch (Exception gex)
        {
            throw new RuntimeException(gex.getMessage(), gex);
        }
    }

    public byte[] getKey()
    {
        if (secretKey == null)
        {
            throw new IllegalStateException("no secret key recovered");
        }

        return secretKey.getEncoded();
    }


    public static Builder builder(PrivateKey privateKey, byte[] recipientHash)
    {
        return new Builder(privateKey, recipientHash);
    }

    public static class Builder
    {
        private JcaJceHelper provider;
        private final byte[] recipientHash;
        private final PrivateKey key;

        public Builder(PrivateKey key, byte[] recipientHash)
        {
            this.key = key;
            this.recipientHash = Arrays.clone(recipientHash);
        }

        public Builder provider(Provider provider)
        {
            this.provider = new ProviderJcaJceHelper(provider);
            return this;
        }

        public Builder provider(String provider)
        {
            this.provider = new NamedJcaJceHelper(provider);
            return this;
        }

        public JcaETSIDataDecryptor build()
        {
            return new JcaETSIDataDecryptor(key, recipientHash, provider);
        }
    }


}