201 lines
7.6 KiB
Java
201 lines
7.6 KiB
Java
/*
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* Copyright (C) 2017 Schürmann & Breitmoser GbR
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.sufficientlysecure.keychain.securitytoken;
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import androidx.annotation.Nullable;
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import com.google.auto.value.AutoValue;
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import org.bouncycastle.asn1.ASN1ObjectIdentifier;
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import org.bouncycastle.asn1.nist.NISTNamedCurves;
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import org.bouncycastle.asn1.x9.ECNamedCurveTable;
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import org.bouncycastle.asn1.x9.X9ECParameters;
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import org.bouncycastle.bcpg.PublicKeyAlgorithmTags;
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import org.bouncycastle.bcpg.sig.KeyFlags;
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import org.bouncycastle.math.ec.ECCurve;
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import org.bouncycastle.util.Arrays;
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import org.sufficientlysecure.keychain.service.SaveKeyringParcel;
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import org.sufficientlysecure.keychain.service.SaveKeyringParcel.SubkeyAdd;
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import java.io.IOException;
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import timber.log.Timber;
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// 4.3.3.6 Algorithm Attributes
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@AutoValue
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public abstract class ECKeyFormat extends KeyFormat {
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public abstract byte[] oidField();
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@Nullable // TODO
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public abstract ECAlgorithmFormat ecAlgorithmFormat();
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private static final byte ATTRS_IMPORT_FORMAT_WITH_PUBKEY = (byte) 0xff;
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ECKeyFormat() {
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super(KeyFormatType.ECKeyFormatType);
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}
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public static KeyFormat getInstance(byte[] oidField, ECAlgorithmFormat from) {
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return new AutoValue_ECKeyFormat(oidField, from);
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}
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public static ECKeyFormat getInstance(ASN1ObjectIdentifier oidAsn1, ECAlgorithmFormat from) {
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byte[] oidField = asn1ToOidField(oidAsn1);
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return new AutoValue_ECKeyFormat(oidField, from);
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}
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public static KeyFormat getInstanceFromBytes(byte[] bytes) {
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if (bytes.length < 2) {
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throw new IllegalArgumentException("Bad length for EC attributes");
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}
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int len = bytes.length - 1;
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if (bytes[bytes.length - 1] == ATTRS_IMPORT_FORMAT_WITH_PUBKEY) {
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len -= 1;
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}
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final byte[] oidField = new byte[len];
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System.arraycopy(bytes, 1, oidField, 0, len);
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return getInstance(oidField, ECKeyFormat.ECAlgorithmFormat.from(bytes[0], bytes[bytes.length - 1]));
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}
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public byte[] toBytes(KeyType slot) {
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byte[] attrs = new byte[1 + oidField().length + 1];
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attrs[0] = ecAlgorithmFormat().getAlgorithmId();
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System.arraycopy(oidField(), 0, attrs, 1, oidField().length);
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attrs[attrs.length - 1] = ATTRS_IMPORT_FORMAT_WITH_PUBKEY;
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return attrs;
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}
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public ASN1ObjectIdentifier asn1ParseOid() {
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ASN1ObjectIdentifier asn1CurveOid = oidFieldToOidAsn1(oidField());
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String curveName = ECNamedCurveTable.getName(asn1CurveOid);
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if (curveName == null) {
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Timber.w("Unknown curve OID: %s. Could be YubiKey firmware bug < 5.2.8. Trying again with last byte removed.", asn1CurveOid.getId());
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// https://bugs.chromium.org/p/chromium/issues/detail?id=1120933#c10
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// The OpenPGP applet of a Yubikey with firmware version below 5.2.8 appends
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// a potentially arbitrary byte to the intended byte representation of an ECC
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// curve OID. This case is handled by retrying the decoding with the last
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// byte stripped if the resulting OID does not label a known curve.
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byte[] oidRemoveLastByte = Arrays.copyOf(oidField(), oidField().length - 1);
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ASN1ObjectIdentifier asn1CurveOidYubikey = oidFieldToOidAsn1(oidRemoveLastByte);
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curveName = ECNamedCurveTable.getName(asn1CurveOidYubikey);
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if (curveName != null) {
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Timber.w("Detected curve OID: %s", asn1CurveOidYubikey.getId());
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return asn1CurveOidYubikey;
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} else {
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Timber.e("Still Unknown curve OID: %s", asn1CurveOidYubikey.getId());
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return asn1CurveOid;
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}
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}
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return asn1CurveOid;
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}
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private static byte[] asn1ToOidField(ASN1ObjectIdentifier oidAsn1) {
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byte[] encodedAsn1Oid;
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try {
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encodedAsn1Oid = oidAsn1.getEncoded();
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} catch (IOException e) {
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throw new IllegalStateException("Failed to encode curve OID!");
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}
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byte[] oidField = new byte[encodedAsn1Oid.length - 2];
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System.arraycopy(encodedAsn1Oid, 2, oidField, 0, encodedAsn1Oid.length - 2);
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return oidField;
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}
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private static ASN1ObjectIdentifier oidFieldToOidAsn1(byte[] oidField) {
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final byte[] boid = new byte[2 + oidField.length];
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boid[0] = (byte) 0x06;
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boid[1] = (byte) oidField.length;
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System.arraycopy(oidField, 0, boid, 2, oidField.length);
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return ASN1ObjectIdentifier.getInstance(boid);
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}
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public enum ECAlgorithmFormat {
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ECDH((byte) PublicKeyAlgorithmTags.ECDH, true, false),
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ECDH_WITH_PUBKEY((byte) PublicKeyAlgorithmTags.ECDH, true, true),
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ECDSA((byte) PublicKeyAlgorithmTags.ECDSA, false, false),
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ECDSA_WITH_PUBKEY((byte) PublicKeyAlgorithmTags.ECDSA, false, true);
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private final byte mAlgorithmId;
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private final boolean mIsECDH;
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private final boolean mWithPubkey;
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ECAlgorithmFormat(final byte algorithmId, final boolean isECDH, final boolean withPubkey) {
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mAlgorithmId = algorithmId;
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mIsECDH = isECDH;
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mWithPubkey = withPubkey;
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}
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public static ECKeyFormat.ECAlgorithmFormat from(final byte bFirst, final byte bLast) {
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for (ECKeyFormat.ECAlgorithmFormat format : values()) {
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if (format.mAlgorithmId == bFirst &&
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((bLast == ATTRS_IMPORT_FORMAT_WITH_PUBKEY) == format.isWithPubkey())) {
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return format;
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}
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}
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return null;
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}
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public final byte getAlgorithmId() {
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return mAlgorithmId;
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}
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public final boolean isECDH() {
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return mIsECDH;
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}
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public final boolean isWithPubkey() {
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return mWithPubkey;
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}
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}
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public void addToSaveKeyringParcel(SaveKeyringParcel.Builder builder, int keyFlags) {
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ASN1ObjectIdentifier oidAsn1 = asn1ParseOid();
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final X9ECParameters params = NISTNamedCurves.getByOID(oidAsn1);
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final ECCurve curve = params.getCurve();
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SaveKeyringParcel.Algorithm algo = SaveKeyringParcel.Algorithm.ECDSA;
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if (((keyFlags & KeyFlags.ENCRYPT_COMMS) == KeyFlags.ENCRYPT_COMMS)
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|| ((keyFlags & KeyFlags.ENCRYPT_STORAGE) == KeyFlags.ENCRYPT_STORAGE)) {
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algo = SaveKeyringParcel.Algorithm.ECDH;
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}
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SaveKeyringParcel.Curve scurve;
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if (oidAsn1.equals(NISTNamedCurves.getOID("P-256"))) {
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scurve = SaveKeyringParcel.Curve.NIST_P256;
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} else if (oidAsn1.equals(NISTNamedCurves.getOID("P-384"))) {
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scurve = SaveKeyringParcel.Curve.NIST_P384;
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} else if (oidAsn1.equals(NISTNamedCurves.getOID("P-521"))) {
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scurve = SaveKeyringParcel.Curve.NIST_P521;
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} else {
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throw new IllegalArgumentException("Unsupported curve " + oidAsn1);
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}
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builder.addSubkeyAdd(SubkeyAdd.createSubkeyAdd(algo, curve.getFieldSize(), scurve, keyFlags, 0L));
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}
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}
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