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Kotlin conversion: CachingBcPublicKeyDataDecryptorFactory

This commit is contained in:
Paul Schaub 2023-09-07 14:29:17 +02:00
parent e8fef1f1f3
commit 0b071ff8e1
Signed by: vanitasvitae
GPG Key ID: 62BEE9264BF17311
3 changed files with 50 additions and 103 deletions
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95
pgpainless-core/src/main/java/org/bouncycastle/CachingBcPublicKeyDataDecryptorFactory.java
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// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.bouncycastle;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
import org.bouncycastle.openpgp.operator.bc.BcPublicKeyDataDecryptorFactory;
import org.bouncycastle.util.encoders.Base64;
import org.bouncycastle.util.encoders.Hex;
import org.pgpainless.decryption_verification.CustomPublicKeyDataDecryptorFactory;
import org.pgpainless.key.SubkeyIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.HashMap;
import java.util.Map;
/**
* Implementation of the {@link PublicKeyDataDecryptorFactory} which caches decrypted session keys.
* That way, if a message needs to be decrypted multiple times, expensive private key operations can be omitted.
*
* This implementation changes the behavior or {@link #recoverSessionData(int, byte[][])} to first return any
* cache hits.
* If no hit is found, the method call is delegated to the underlying {@link PublicKeyDataDecryptorFactory}.
* The result of that is then placed in the cache and returned.
*/
public class CachingBcPublicKeyDataDecryptorFactory
extends BcPublicKeyDataDecryptorFactory
implements CustomPublicKeyDataDecryptorFactory {
private static final Logger LOGGER = LoggerFactory.getLogger(CachingBcPublicKeyDataDecryptorFactory.class);
private final Map<String, byte[]> cachedSessionKeys = new HashMap<>();
private final SubkeyIdentifier decryptionKey;
public CachingBcPublicKeyDataDecryptorFactory(PGPPrivateKey privateKey, SubkeyIdentifier decryptionKey) {
super(privateKey);
this.decryptionKey = decryptionKey;
}
@Override
public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData) throws PGPException {
byte[] sessionKey = lookupSessionKeyData(secKeyData);
if (sessionKey == null) {
LOGGER.debug("Cache miss for encrypted session key " + Hex.toHexString(secKeyData[0]));
sessionKey = costlyRecoverSessionData(keyAlgorithm, secKeyData);
cacheSessionKeyData(secKeyData, sessionKey);
} else {
LOGGER.debug("Cache hit for encrypted session key " + Hex.toHexString(secKeyData[0]));
}
return sessionKey;
}
public byte[] costlyRecoverSessionData(int keyAlgorithm, byte[][] secKeyData) throws PGPException {
return super.recoverSessionData(keyAlgorithm, secKeyData);
}
private byte[] lookupSessionKeyData(byte[][] secKeyData) {
String key = toKey(secKeyData);
byte[] sessionKey = cachedSessionKeys.get(key);
return copy(sessionKey);
}
private void cacheSessionKeyData(byte[][] secKeyData, byte[] sessionKey) {
String key = toKey(secKeyData);
cachedSessionKeys.put(key, copy(sessionKey));
}
private static String toKey(byte[][] secKeyData) {
byte[] sk = secKeyData[0];
String key = Base64.toBase64String(sk);
return key;
}
private static byte[] copy(byte[] bytes) {
if (bytes == null) {
return null;
}
byte[] copy = new byte[bytes.length];
System.arraycopy(bytes, 0, copy, 0, copy.length);
return copy;
}
public void clear() {
cachedSessionKeys.clear();
}
@Override
public SubkeyIdentifier getSubkeyIdentifier() {
return decryptionKey;
}
}

8
pgpainless-core/src/main/java/org/bouncycastle/package-info.java
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// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
/**
* Classes which could be upstreamed to BC at some point.
*/
package org.bouncycastle;

50
pgpainless-core/src/main/kotlin/org/bouncycastle/CachingBcPublicKeyDataDecryptorFactory.kt Normal file
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// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.bouncycastle
import org.bouncycastle.openpgp.PGPPrivateKey
import org.bouncycastle.openpgp.operator.bc.BcPublicKeyDataDecryptorFactory
import org.bouncycastle.util.encoders.Base64
import org.pgpainless.decryption_verification.CustomPublicKeyDataDecryptorFactory
import org.pgpainless.key.SubkeyIdentifier
/**
* Implementation of the [PublicKeyDataDecryptorFactory] which caches decrypted session keys.
* That way, if a message needs to be decrypted multiple times, expensive private key operations can be omitted.
*
* This implementation changes the behavior or [recoverSessionData] to first return any
* cache hits.
* If no hit is found, the method call is delegated to the underlying [PublicKeyDataDecryptorFactory].
* The result of that is then placed in the cache and returned.
*/
class CachingBcPublicKeyDataDecryptorFactory(
privateKey: PGPPrivateKey,
override val subkeyIdentifier: SubkeyIdentifier
) : BcPublicKeyDataDecryptorFactory(privateKey), CustomPublicKeyDataDecryptorFactory {
private val cachedSessions: MutableMap<String, ByteArray> = mutableMapOf()
override fun recoverSessionData(keyAlgorithm: Int, secKeyData: Array<out ByteArray>): ByteArray =
lookupSessionKeyData(secKeyData) ?:
costlyRecoverSessionData(keyAlgorithm, secKeyData)
.also { cacheSessionKeyData(secKeyData, it) }
private fun lookupSessionKeyData(secKeyData: Array<out ByteArray>): ByteArray? =
cachedSessions[toKey(secKeyData)]?.clone()
private fun costlyRecoverSessionData(keyAlgorithm: Int, secKeyData: Array<out ByteArray>): ByteArray =
super.recoverSessionData(keyAlgorithm, secKeyData)
private fun cacheSessionKeyData(secKeyData: Array<out ByteArray>, sessionKey: ByteArray) {
cachedSessions[toKey(secKeyData)] = sessionKey.clone()
}
private fun toKey(secKeyData: Array<out ByteArray>): String =
Base64.toBase64String(secKeyData[0])
fun clear() {
cachedSessions.clear()
}
}