open-keychain/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/RsaKeyFormat.java
2021-03-16 17:07:56 +01:00

121 lines
4.1 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 androidx.annotation.RestrictTo;
import com.google.auto.value.AutoValue;
import org.bouncycastle.bcpg.PublicKeyAlgorithmTags;
import org.sufficientlysecure.keychain.service.SaveKeyringParcel;
import org.sufficientlysecure.keychain.service.SaveKeyringParcel.SubkeyAdd;
// OpenPGP Card Spec: Algorithm Attributes: RSA
@AutoValue
public abstract class RsaKeyFormat extends KeyFormat {
public static final int ALGORITHM_ID = PublicKeyAlgorithmTags.RSA_GENERAL;
public abstract int modulusLength();
public abstract int exponentLength();
public abstract RsaImportFormat rsaImportFormat();
public static RsaKeyFormat getInstance(int modulusLength, int exponentLength, RsaImportFormat from) {
return new AutoValue_RsaKeyFormat(modulusLength, exponentLength, from);
}
public static RsaKeyFormat getInstanceDefault2048BitFormat() {
return getInstance(2048, 4, RsaImportFormat.CRT_WITH_MODULUS);
}
public RsaKeyFormat withModulus(int modulus) {
return RsaKeyFormat.getInstance(modulus, exponentLength(), rsaImportFormat());
}
public static KeyFormat getInstanceFromBytes(byte[] bytes) {
if (bytes.length < 6) {
throw new IllegalArgumentException("Bad length for RSA attributes");
}
int modulusLength = bytes[1] << 8 | bytes[2];
int exponentLength = bytes[3] << 8 | bytes[4];
RsaImportFormat importFormat = RsaImportFormat.from(bytes[5]);
return getInstance(modulusLength, exponentLength, importFormat);
}
@Override
public byte[] toBytes(KeyType slot) {
int i = 0;
byte[] attrs = new byte[6];
attrs[i++] = (byte) ALGORITHM_ID;
attrs[i++] = (byte) ((modulusLength() >> 8) & 0xff);
attrs[i++] = (byte) (modulusLength() & 0xff);
attrs[i++] = (byte) ((exponentLength() >> 8) & 0xff);
attrs[i++] = (byte) (exponentLength() & 0xff);
attrs[i] = rsaImportFormat().getImportFormat();
return attrs;
}
public enum RsaImportFormat {
STANDARD((byte) 0x00, false, false),
STANDARD_WITH_MODULUS((byte) 0x01, false, true),
CRT((byte) 0x02, true, false),
CRT_WITH_MODULUS((byte) 0x03, true, true);
private byte importFormat;
private boolean includeModulus;
private boolean includeCrt;
RsaImportFormat(byte importFormat, boolean includeCrt, boolean includeModulus) {
this.importFormat = importFormat;
this.includeModulus = includeModulus;
this.includeCrt = includeCrt;
}
public static RsaImportFormat from(byte importFormatByte) {
for (RsaImportFormat format : values()) {
if (format.importFormat == importFormatByte) {
return format;
}
}
return null;
}
public byte getImportFormat() {
return importFormat;
}
public boolean isIncludeModulus() {
return includeModulus;
}
public boolean isIncludeCrt() {
return includeCrt;
}
}
public void addToSaveKeyringParcel(SaveKeyringParcel.Builder builder, int keyFlags) {
builder.addSubkeyAdd(SubkeyAdd.createSubkeyAdd(SaveKeyringParcel.Algorithm.RSA,
modulusLength(), null, keyFlags, 0L));
}
}