106 lines
3.9 KiB
Java
106 lines
3.9 KiB
Java
// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
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//
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// SPDX-License-Identifier: Apache-2.0
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package org.pgpainless.decryption_verification;
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import org.bouncycastle.bcpg.AEADEncDataPacket;
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import org.bouncycastle.bcpg.SymmetricEncIntegrityPacket;
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import org.bouncycastle.openpgp.PGPException;
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import org.bouncycastle.openpgp.PGPSessionKey;
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import org.bouncycastle.openpgp.operator.PGPDataDecryptor;
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import org.bouncycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
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import org.bouncycastle.openpgp.operator.bc.BcPublicKeyDataDecryptorFactory;
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import org.pgpainless.key.SubkeyIdentifier;
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/**
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* Enable integration of hardware-backed OpenPGP keys.
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*/
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public class HardwareSecurity {
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public interface DecryptionCallback {
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/**
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* Delegate decryption of a Public-Key-Encrypted-Session-Key (PKESK) to an external API for dealing with
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* hardware security modules such as smartcards or TPMs.
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*
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* If decryption fails for some reason, a subclass of the {@link HardwareSecurityException} is thrown.
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*
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* @param keyId id of the key
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* @param keyAlgorithm algorithm
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* @param sessionKeyData encrypted session key
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*
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* @return decrypted session key
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* @throws HardwareSecurityException exception
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*/
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byte[] decryptSessionKey(long keyId, int keyAlgorithm, byte[] sessionKeyData)
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throws HardwareSecurityException;
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}
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/**
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* Implementation of {@link PublicKeyDataDecryptorFactory} which delegates decryption of encrypted session keys
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* to a {@link DecryptionCallback}.
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* Users can provide such a callback to delegate decryption of messages to hardware security SDKs.
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*/
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public static class HardwareDataDecryptorFactory implements CustomPublicKeyDataDecryptorFactory {
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private final DecryptionCallback callback;
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// luckily we can instantiate the BcPublicKeyDataDecryptorFactory with null as argument.
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private final PublicKeyDataDecryptorFactory factory =
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new BcPublicKeyDataDecryptorFactory(null);
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private final SubkeyIdentifier subkey;
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/**
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* Create a new {@link HardwareDataDecryptorFactory}.
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*
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* @param subkeyIdentifier identifier of the decryption subkey
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* @param callback decryption callback
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*/
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public HardwareDataDecryptorFactory(SubkeyIdentifier subkeyIdentifier, DecryptionCallback callback) {
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this.callback = callback;
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this.subkey = subkeyIdentifier;
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}
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@Override
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public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
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throws PGPException {
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try {
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// delegate decryption to the callback
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return callback.decryptSessionKey(subkey.getSubkeyId(), keyAlgorithm, secKeyData[0]);
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} catch (HardwareSecurityException e) {
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throw new PGPException("Hardware-backed decryption failed.", e);
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}
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}
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@Override
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public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
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throws PGPException {
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return factory.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
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}
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@Override
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public PGPDataDecryptor createDataDecryptor(AEADEncDataPacket aeadEncDataPacket, PGPSessionKey sessionKey)
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throws PGPException {
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return factory.createDataDecryptor(aeadEncDataPacket, sessionKey);
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}
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@Override
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public PGPDataDecryptor createDataDecryptor(SymmetricEncIntegrityPacket seipd, PGPSessionKey sessionKey)
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throws PGPException {
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return factory.createDataDecryptor(seipd, sessionKey);
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}
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@Override
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public SubkeyIdentifier getSubkeyIdentifier() {
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return subkey;
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}
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}
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public static class HardwareSecurityException
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extends Exception {
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}
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}
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