and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+package org.eclipse.jgit.gpg.bc.internal.keys;
+
+import java.math.BigInteger;
+import java.nio.charset.StandardCharsets;
+import java.text.MessageFormat;
+import java.util.Arrays;
+
+import org.bouncycastle.asn1.ASN1ObjectIdentifier;
+import org.bouncycastle.asn1.cryptlib.CryptlibObjectIdentifiers;
+import org.bouncycastle.asn1.x9.ECNamedCurveTable;
+import org.bouncycastle.asn1.x9.X9ECParameters;
+import org.bouncycastle.bcpg.DSAPublicBCPGKey;
+import org.bouncycastle.bcpg.ECPublicBCPGKey;
+import org.bouncycastle.bcpg.ElGamalPublicBCPGKey;
+import org.bouncycastle.bcpg.PublicKeyAlgorithmTags;
+import org.bouncycastle.bcpg.RSAPublicBCPGKey;
+import org.bouncycastle.crypto.ec.CustomNamedCurves;
+import org.bouncycastle.math.ec.ECAlgorithms;
+import org.bouncycastle.math.field.FiniteField;
+import org.bouncycastle.openpgp.PGPException;
+import org.bouncycastle.openpgp.PGPPublicKey;
+import org.bouncycastle.util.encoders.Hex;
+import org.eclipse.jgit.annotations.NonNull;
+import org.eclipse.jgit.gpg.bc.internal.BCText;
+import org.eclipse.jgit.util.sha1.SHA1;
+
+/**
+ * Utilities to compute the keygrip of a key. A keygrip is a SHA1 hash
+ * over the public key parameters and is used internally by the gpg-agent to
+ * find the secret key belonging to a public key: the secret key is stored in a
+ * file under ~/.gnupg/private-keys-v1.d/ with a name "<keygrip>.key". While
+ * this storage organization is an implementation detail of GPG, the way
+ * keygrips are computed is not; they are computed by libgcrypt and their
+ * definition is stable.
+ */
+public final class KeyGrip {
+
+ // Some OIDs apparently unknown to BouncyCastle.
+
+ private static String OID_OPENPGP_ED25519 = "1.3.6.1.4.1.11591.15.1"; //$NON-NLS-1$
+
+ private static String OID_RFC8410_CURVE25519 = "1.3.101.110"; //$NON-NLS-1$
+
+ private static String OID_RFC8410_ED25519 = "1.3.101.112"; //$NON-NLS-1$
+
+ private KeyGrip() {
+ // No instantiation
+ }
+
+ /**
+ * Computes the keygrip for a {@link PGPPublicKey}.
+ *
+ * @param publicKey
+ * to get the keygrip of
+ * @return the keygrip
+ * @throws PGPException
+ * if an unknown key type is encountered.
+ */
+ @NonNull
+ public static byte[] getKeyGrip(PGPPublicKey publicKey)
+ throws PGPException {
+ SHA1 grip = SHA1.newInstance();
+ grip.setDetectCollision(false);
+
+ switch (publicKey.getAlgorithm()) {
+ case PublicKeyAlgorithmTags.RSA_GENERAL:
+ case PublicKeyAlgorithmTags.RSA_ENCRYPT:
+ case PublicKeyAlgorithmTags.RSA_SIGN:
+ BigInteger modulus = ((RSAPublicBCPGKey) publicKey
+ .getPublicKeyPacket().getKey()).getModulus();
+ hash(grip, modulus.toByteArray());
+ break;
+ case PublicKeyAlgorithmTags.DSA:
+ DSAPublicBCPGKey dsa = (DSAPublicBCPGKey) publicKey
+ .getPublicKeyPacket().getKey();
+ hash(grip, dsa.getP().toByteArray(), 'p', true);
+ hash(grip, dsa.getQ().toByteArray(), 'q', true);
+ hash(grip, dsa.getG().toByteArray(), 'g', true);
+ hash(grip, dsa.getY().toByteArray(), 'y', true);
+ break;
+ case PublicKeyAlgorithmTags.ELGAMAL_GENERAL:
+ case PublicKeyAlgorithmTags.ELGAMAL_ENCRYPT:
+ ElGamalPublicBCPGKey eg = (ElGamalPublicBCPGKey) publicKey
+ .getPublicKeyPacket().getKey();
+ hash(grip, eg.getP().toByteArray(), 'p', true);
+ hash(grip, eg.getG().toByteArray(), 'g', true);
+ hash(grip, eg.getY().toByteArray(), 'y', true);
+ break;
+ case PublicKeyAlgorithmTags.ECDH:
+ case PublicKeyAlgorithmTags.ECDSA:
+ case PublicKeyAlgorithmTags.EDDSA:
+ ECPublicBCPGKey ec = (ECPublicBCPGKey) publicKey
+ .getPublicKeyPacket().getKey();
+ ASN1ObjectIdentifier curveOID = ec.getCurveOID();
+ // BC doesn't know these OIDs.
+ if (OID_OPENPGP_ED25519.equals(curveOID.getId())
+ || OID_RFC8410_ED25519.equals(curveOID.getId())) {
+ return hashEd25519(grip, ec.getEncodedPoint());
+ } else if (CryptlibObjectIdentifiers.curvey25519.equals(curveOID)
+ || OID_RFC8410_CURVE25519.equals(curveOID.getId())) {
+ // curvey25519 actually is the OpenPGP OID for Curve25519 and is
+ // known to BC, but the parameters are for the short Weierstrass
+ // form. See https://github.com/bcgit/bc-java/issues/399 .
+ // libgcrypt uses Montgomery form.
+ return hashCurve25519(grip, ec.getEncodedPoint());
+ }
+ X9ECParameters params = getX9Parameters(curveOID);
+ if (params == null) {
+ throw new PGPException(MessageFormat
+ .format(BCText.get().unknownCurve, curveOID.getId()));
+ }
+ // Need to write p, a, b, g, n, q
+ BigInteger q = ec.getEncodedPoint();
+ byte[] g = params.getG().getEncoded(false);
+ BigInteger a = params.getCurve().getA().toBigInteger();
+ BigInteger b = params.getCurve().getB().toBigInteger();
+ BigInteger n = params.getN();
+ BigInteger p = null;
+ FiniteField field = params.getCurve().getField();
+ if (ECAlgorithms.isFpField(field)) {
+ p = field.getCharacteristic();
+ }
+ if (p == null) {
+ // Don't know...
+ throw new PGPException(MessageFormat.format(
+ BCText.get().unknownCurveParameters, curveOID.getId()));
+ }
+ hash(grip, p.toByteArray(), 'p', false);
+ hash(grip, a.toByteArray(), 'a', false);
+ hash(grip, b.toByteArray(), 'b', false);
+ hash(grip, g, 'g', false);
+ hash(grip, n.toByteArray(), 'n', false);
+ if (publicKey.getAlgorithm() == PublicKeyAlgorithmTags.EDDSA) {
+ hashQ25519(grip, q);
+ } else {
+ hash(grip, q.toByteArray(), 'q', false);
+ }
+ break;
+ default:
+ throw new PGPException(
+ MessageFormat.format(BCText.get().unknownKeyType,
+ Integer.toString(publicKey.getAlgorithm())));
+ }
+ return grip.digest();
+ }
+
+ private static void hash(SHA1 grip, byte[] data) {
+ // Need to skip leading zero bytes
+ int i = 0;
+ while (i < data.length && data[i] == 0) {
+ i++;
+ }
+ int length = data.length - i;
+ if (i < data.length) {
+ if ((data[i] & 0x80) != 0) {
+ grip.update((byte) 0);
+ }
+ grip.update(data, i, length);
+ }
+ }
+
+ private static void hash(SHA1 grip, byte[] data, char id, boolean zeroPad) {
+ // Need to skip leading zero bytes
+ int i = 0;
+ while (i < data.length && data[i] == 0) {
+ i++;
+ }
+ int length = data.length - i;
+ boolean addZero = false;
+ if (i < data.length && zeroPad && (data[i] & 0x80) != 0) {
+ addZero = true;
+ }
+ // libgcrypt includes an SExp in the hash
+ String prefix = "(1:" + id + (addZero ? length + 1 : length) + ':'; //$NON-NLS-1$
+ grip.update(prefix.getBytes(StandardCharsets.US_ASCII));
+ // For some items, gcrypt prepends a zero byte if the high bit is set
+ if (addZero) {
+ grip.update((byte) 0);
+ }
+ if (i < data.length) {
+ grip.update(data, i, length);
+ }
+ grip.update((byte) ')');
+ }
+
+ private static void hashQ25519(SHA1 grip, BigInteger q)
+ throws PGPException {
+ byte[] data = q.toByteArray();
+ switch (data[0]) {
+ case 0x04:
+ if (data.length != 65) {
+ throw new PGPException(MessageFormat.format(
+ BCText.get().corrupt25519Key, Hex.toHexString(data)));
+ }
+ // Uncompressed: should not occur with ed25519 or curve25519
+ throw new PGPException(MessageFormat.format(
+ BCText.get().uncompressed25519Key, Hex.toHexString(data)));
+ case 0x40:
+ if (data.length != 33) {
+ throw new PGPException(MessageFormat.format(
+ BCText.get().corrupt25519Key, Hex.toHexString(data)));
+ }
+ // Compressed; normal case. Skip prefix.
+ hash(grip, Arrays.copyOfRange(data, 1, data.length), 'q', false);
+ break;
+ default:
+ if (data.length != 32) {
+ throw new PGPException(MessageFormat.format(
+ BCText.get().corrupt25519Key, Hex.toHexString(data)));
+ }
+ // Compressed format without prefix. Should not occur?
+ hash(grip, data, 'q', false);
+ break;
+ }
+ }
+
+ /**
+ * Computes the keygrip for an ed25519 public key.
+ *
+ * Package-visible for tests only.
+ *
+ *
+ * @param grip
+ * initialized {@link SHA1}
+ * @param q
+ * the public key's EC point
+ * @return the keygrip
+ * @throws PGPException
+ * if q indicates uncompressed format
+ */
+ @SuppressWarnings("nls")
+ static byte[] hashEd25519(SHA1 grip, BigInteger q) throws PGPException {
+ // For the values, see RFC 7748: https://tools.ietf.org/html/rfc7748
+ // p = 2^255 - 19
+ hash(grip, Hex.decodeStrict(
+ "7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFED"),
+ 'p', false);
+ // Field: a = 1
+ hash(grip, new byte[] { 0x01 }, 'a', false);
+ // Field: b = 121665/121666 (mod p)
+ // See Berstein et.al., "Twisted Edwards Curves",
+ // https://doi.org/10.1007/978-3-540-68164-9_26
+ hash(grip, Hex.decodeStrict(
+ "2DFC9311D490018C7338BF8688861767FF8FF5B2BEBE27548A14B235ECA6874A"),
+ 'b', false);
+ // Generator point with affine X,Y
+ // @formatter:off
+ // X(P) = 15112221349535400772501151409588531511454012693041857206046113283949847762202
+ // Y(P) = 46316835694926478169428394003475163141307993866256225615783033603165251855960
+ // the "04" signifies uncompressed format.
+ // @formatter:on
+ hash(grip, Hex.decodeStrict("04"
+ + "216936D3CD6E53FEC0A4E231FDD6DC5C692CC7609525A7B2C9562D608F25D51A"
+ + "6666666666666666666666666666666666666666666666666666666666666658"),
+ 'g', false);
+ // order = 2^252 + 0x14def9dea2f79cd65812631a5cf5d3ed
+ hash(grip, Hex.decodeStrict(
+ "1000000000000000000000000000000014DEF9DEA2F79CD65812631A5CF5D3ED"),
+ 'n', false);
+ hashQ25519(grip, q);
+ return grip.digest();
+ }
+
+ /**
+ * Computes the keygrip for a curve25519 public key.
+ *
+ * Package-visible for tests only.
+ *
+ *
+ * @param grip
+ * initialized {@link SHA1}
+ * @param q
+ * the public key's EC point
+ * @return the keygrip
+ * @throws PGPException
+ * if q indicates uncompressed format
+ */
+ @SuppressWarnings("nls")
+ static byte[] hashCurve25519(SHA1 grip, BigInteger q) throws PGPException {
+ hash(grip, Hex.decodeStrict(
+ "7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFED"),
+ 'p', false);
+ // Unclear: RFC 7748 says A = 486662. This value here is (A-2)/4 =
+ // 121665. Compare ecc-curves.c in libgcrypt:
+ // https://github.com/gpg/libgcrypt/blob/361a058/cipher/ecc-curves.c#L146
+ hash(grip, new byte[] { 0x01, (byte) 0xDB, 0x41 }, 'a', false);
+ hash(grip, new byte[] { 0x01 }, 'b', false);
+ // libgcrypt uses the old g.y value before the erratum to RFC 7748 for
+ // the keygrip. The new value would be
+ // 5F51E65E475F794B1FE122D388B72EB36DC2B28192839E4DD6163A5D81312C14. See
+ // https://www.rfc-editor.org/errata/eid4730 and
+ // https://github.com/gpg/libgcrypt/commit/f67b6492e0b0
+ hash(grip, Hex.decodeStrict("04"
+ + "0000000000000000000000000000000000000000000000000000000000000009"
+ + "20AE19A1B8A086B4E01EDD2C7748D14C923D4D7E6D7C61B229E9C5A27ECED3D9"),
+ 'g', false);
+ hash(grip, Hex.decodeStrict(
+ "1000000000000000000000000000000014DEF9DEA2F79CD65812631A5CF5D3ED"),
+ 'n', false);
+ hashQ25519(grip, q);
+ return grip.digest();
+ }
+
+ private static X9ECParameters getX9Parameters(
+ ASN1ObjectIdentifier curveOID) {
+ X9ECParameters params = CustomNamedCurves.getByOID(curveOID);
+ if (params == null) {
+ params = ECNamedCurveTable.getByOID(curveOID);
+ }
+ return params;
+ }
+
+}