88 lines
2.7 KiB
Java
88 lines
2.7 KiB
Java
// SPDX-FileCopyrightText: 2018 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.util;
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import java.security.NoSuchAlgorithmException;
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import org.bouncycastle.asn1.ASN1ObjectIdentifier;
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import org.bouncycastle.bcpg.ECPublicBCPGKey;
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import org.bouncycastle.openpgp.PGPPublicKey;
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public final class BCUtil {
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private BCUtil() {
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}
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/**
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* Utility method to get the bit strength of OpenPGP keys.
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* Bouncycastle is lacking support for some keys (eg. EdDSA, X25519), so this method
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* manually derives the bit strength from the keys curves OID.
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*
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* @param key key
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* @return bit strength
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*/
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public static int getBitStrength(PGPPublicKey key) throws NoSuchAlgorithmException {
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int bitStrength = key.getBitStrength();
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if (bitStrength == -1) {
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// BC's PGPPublicKey.getBitStrength() does fail for some keys (EdDSA, X25519)
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// therefore we manually set the bit strength.
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// see https://github.com/bcgit/bc-java/issues/972
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ASN1ObjectIdentifier oid = ((ECPublicBCPGKey) key.getPublicKeyPacket().getKey()).getCurveOID();
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if (oid.getId().equals("1.3.6.1.4.1.11591.15.1")) {
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// ed25519 is 256 bits
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bitStrength = 256;
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} else if (oid.getId().equals("1.3.6.1.4.1.3029.1.5.1")) {
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// curvey25519 is 256 bits
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bitStrength = 256;
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} else {
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throw new NoSuchAlgorithmException("Unknown curve: " + oid.getId());
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}
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}
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return bitStrength;
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}
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/**
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* A constant time equals comparison - does not terminate early if
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* test will fail. For best results always pass the expected value
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* as the first parameter.
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*
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* @param expected first array
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* @param supplied second array
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* @return true if arrays equal, false otherwise.
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*/
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public static boolean constantTimeAreEqual(
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char[] expected,
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char[] supplied) {
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if (expected == null || supplied == null) {
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return false;
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}
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if (expected == supplied) {
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return true;
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}
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int len = Math.min(expected.length, supplied.length);
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int nonEqual = expected.length ^ supplied.length;
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// do the char-wise comparison
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for (int i = 0; i != len; i++) {
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nonEqual |= (expected[i] ^ supplied[i]);
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}
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// If supplied is longer than expected, iterate over rest of supplied with NOPs
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for (int i = len; i < supplied.length; i++) {
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nonEqual |= ((byte) supplied[i] ^ (byte) ~supplied[i]);
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}
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return nonEqual == 0;
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}
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}
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