open-keychain/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/EcKeyFormat.java

132 lines
4.7 KiB
Java

/*
* Copyright (C) 2017 Schürmann & Breitmoser GbR
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.sufficientlysecure.keychain.securitytoken;
import com.google.auto.value.AutoValue;
import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.nist.NISTNamedCurves;
import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.bcpg.PublicKeyAlgorithmTags;
import org.bouncycastle.bcpg.sig.KeyFlags;
import org.bouncycastle.math.ec.ECCurve;
import org.sufficientlysecure.keychain.service.SaveKeyringParcel;
import org.sufficientlysecure.keychain.service.SaveKeyringParcel.SubkeyAdd;
// OpenPGP Card Spec: Algorithm Attributes: ECC
@AutoValue
public abstract class EcKeyFormat extends KeyFormat {
public abstract int algorithmId();
public abstract ASN1ObjectIdentifier curveOid();
public abstract boolean withPubkey();
private static final byte ATTRS_IMPORT_FORMAT_WITH_PUBKEY = (byte) 0xff;
public static EcKeyFormat getInstance(int algorithmId, ASN1ObjectIdentifier oid, boolean withPubkey) {
return new AutoValue_EcKeyFormat(algorithmId, oid, withPubkey);
}
public static EcKeyFormat getInstanceForKeyGeneration(KeyType keyType, ASN1ObjectIdentifier oidAsn1) {
if (keyType == KeyType.ENCRYPT) {
return getInstance(PublicKeyAlgorithmTags.ECDH, oidAsn1, true);
} else { // SIGN, AUTH
if (EcObjectIdentifiers.ED25519.equals(oidAsn1)) {
return getInstance(PublicKeyAlgorithmTags.EDDSA, oidAsn1, true);
} else {
return getInstance(PublicKeyAlgorithmTags.ECDSA, oidAsn1, true);
}
}
}
public static EcKeyFormat getInstanceFromBytes(byte[] bytes) {
if (bytes.length < 2) {
throw new IllegalArgumentException("Bad length for EC attributes");
}
int algorithmId = bytes[0];
int oidLen = bytes.length - 1;
boolean withPubkey = false;
if (bytes[bytes.length - 1] == ATTRS_IMPORT_FORMAT_WITH_PUBKEY) {
withPubkey = true;
oidLen -= 1;
}
final byte[] oidField = new byte[oidLen];
System.arraycopy(bytes, 1, oidField, 0, oidLen);
ASN1ObjectIdentifier oid = EcObjectIdentifiers.parseOid(oidField);
return getInstance(algorithmId, oid, withPubkey);
}
public byte[] toBytes(KeyType slot) {
byte[] oidField = EcObjectIdentifiers.asn1ToOidField(curveOid());
int len = 1 + oidField.length;
if (withPubkey()) {
len += 1;
}
byte[] attrs = new byte[len];
attrs[0] = (byte) algorithmId();
System.arraycopy(oidField, 0, attrs, 1, oidField.length);
if (withPubkey()) {
attrs[len - 1] = ATTRS_IMPORT_FORMAT_WITH_PUBKEY;
}
return attrs;
}
public boolean isX25519() {
return EcObjectIdentifiers.X25519.equals(curveOid());
}
public final boolean isEdDsa() {
return algorithmId() == PublicKeyAlgorithmTags.EDDSA;
}
public void addToSaveKeyringParcel(SaveKeyringParcel.Builder builder, int keyFlags) {
final X9ECParameters params = NISTNamedCurves.getByOID(curveOid());
final ECCurve curve = params.getCurve();
SaveKeyringParcel.Algorithm algo = SaveKeyringParcel.Algorithm.ECDSA;
if (((keyFlags & KeyFlags.ENCRYPT_COMMS) == KeyFlags.ENCRYPT_COMMS)
|| ((keyFlags & KeyFlags.ENCRYPT_STORAGE) == KeyFlags.ENCRYPT_STORAGE)) {
algo = SaveKeyringParcel.Algorithm.ECDH;
}
SaveKeyringParcel.Curve scurve;
if (EcObjectIdentifiers.NIST_P_256.equals(curveOid())) {
scurve = SaveKeyringParcel.Curve.NIST_P256;
} else if (EcObjectIdentifiers.NIST_P_384.equals(curveOid())) {
scurve = SaveKeyringParcel.Curve.NIST_P384;
} else if (EcObjectIdentifiers.NIST_P_521.equals(curveOid())) {
scurve = SaveKeyringParcel.Curve.NIST_P521;
} else {
throw new IllegalArgumentException("Unsupported curve " + curveOid());
}
builder.addSubkeyAdd(SubkeyAdd.createSubkeyAdd(algo, curve.getFieldSize(), scurve, keyFlags, 0L));
}
}