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/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.ike.ikev2.message;
import android.annotation.StringDef;
import com.android.ike.ikev2.exceptions.AuthenticationFailedException;
import com.android.ike.ikev2.exceptions.IkeException;
import com.android.ike.ikev2.message.IkeAuthPayload.AuthMethod;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.nio.ByteBuffer;
import java.util.Arrays;
/**
* IkeAuthDigitalSignPayload represents Authentication Payload using a specific or generic digital
* signature authentication method.
*
* <p>If AUTH_METHOD_RSA_DIGITAL_SIGN is used, then the hash algorithm is SHA1. If
* AUTH_METHOD_GENERIC_DIGITAL_SIGN is used, the signature algorihtm and hash algorithm are
* extracted from authentication data.
*
* @see <a href="https://tools.ietf.org/html/rfc7296#section-3.8">RFC 7296, Internet Key Exchange
* Protocol Version 2 (IKEv2)</a>
* @see <a href="https://tools.ietf.org/html/rfc7427">RFC 7427, Signature Authentication in the
* Internet Key Exchange Version 2 (IKEv2)</a>
*/
public class IkeAuthDigitalSignPayload extends IkeAuthPayload {
// Byte arrays of DER encoded identifier ASN.1 objects that indicates the algorithm used to
// generate the signature, extracted from
// <a href="https://tools.ietf.org/html/rfc7427#appendix-A"> RFC 7427. There is no need to
// understand the encoding process. They are just constants to indicate the algorithm type.
private static final byte[] PKI_ALGO_ID_DER_BYTES_RSA_SHA1 = {
(byte) 0x30, (byte) 0x0d, (byte) 0x06, (byte) 0x09,
(byte) 0x2a, (byte) 0x86, (byte) 0x48, (byte) 0x86,
(byte) 0xf7, (byte) 0x0d, (byte) 0x01, (byte) 0x01,
(byte) 0x05, (byte) 0x05, (byte) 0x00
};
private static final byte[] PKI_ALGO_ID_DER_BYTES_RSA_SHA2_256 = {
(byte) 0x30, (byte) 0x0d, (byte) 0x06, (byte) 0x09,
(byte) 0x2a, (byte) 0x86, (byte) 0x48, (byte) 0x86,
(byte) 0xf7, (byte) 0x0d, (byte) 0x01, (byte) 0x01,
(byte) 0x0b, (byte) 0x05, (byte) 0x00
};
private static final byte[] PKI_ALGO_ID_DER_BYTES_RSA_SHA2_384 = {
(byte) 0x30, (byte) 0x0d, (byte) 0x06, (byte) 0x09,
(byte) 0x2a, (byte) 0x86, (byte) 0x48, (byte) 0x86,
(byte) 0xf7, (byte) 0x0d, (byte) 0x01, (byte) 0x01,
(byte) 0x0c, (byte) 0x05, (byte) 0x00
};
private static final byte[] PKI_ALGO_ID_DER_BYTES_RSA_SHA2_512 = {
(byte) 0x30, (byte) 0x0d, (byte) 0x06, (byte) 0x09,
(byte) 0x2a, (byte) 0x86, (byte) 0x48, (byte) 0x86,
(byte) 0xf7, (byte) 0x0d, (byte) 0x01, (byte) 0x01,
(byte) 0x0d, (byte) 0x05, (byte) 0x00
};
// Length of ASN.1 object length field.
private static final int SIGNATURE_ALGO_ASN1_LEN_LEN = 1;
// Currently we only support RSA for signature algorithm.
@Retention(RetentionPolicy.SOURCE)
@StringDef({
SIGNATURE_ALGO_RSA_SHA1,
SIGNATURE_ALGO_RSA_SHA2_256,
SIGNATURE_ALGO_RSA_SHA2_384,
SIGNATURE_ALGO_RSA_SHA2_512
})
public @interface SignatureAlgo {}
public static final String SIGNATURE_ALGO_RSA_SHA1 = "SHA1withRSA";
public static final String SIGNATURE_ALGO_RSA_SHA2_256 = "SHA256withRSA";
public static final String SIGNATURE_ALGO_RSA_SHA2_384 = "SHA384withRSA";
public static final String SIGNATURE_ALGO_RSA_SHA2_512 = "SHA512withRSA";
// TODO: Allow users to configure authentication method using @SignatureAlgo
public final String signatureAlgoAndHash;
public final byte[] signature;
protected IkeAuthDigitalSignPayload(
boolean critical, @AuthMethod int authMethod, byte[] authData) throws IkeException {
super(critical, authMethod);
switch (authMethod) {
case AUTH_METHOD_RSA_DIGITAL_SIGN:
signatureAlgoAndHash = SIGNATURE_ALGO_RSA_SHA1;
signature = authData;
break;
case AUTH_METHOD_GENERIC_DIGITAL_SIGN:
ByteBuffer inputBuffer = ByteBuffer.wrap(authData);
// Get signature algorithm.
int signAlgoLen = Byte.toUnsignedInt(inputBuffer.get());
byte[] signAlgoBytes = new byte[signAlgoLen];
inputBuffer.get(signAlgoBytes);
signatureAlgoAndHash = bytesToSignAlgoName(signAlgoBytes);
// Get signature.
signature = new byte[authData.length - SIGNATURE_ALGO_ASN1_LEN_LEN - signAlgoLen];
inputBuffer.get(signature);
break;
default:
// Won't hit here.
throw new IllegalArgumentException("Unrecognized authentication method.");
}
}
private String bytesToSignAlgoName(byte[] signAlgoBytes) throws AuthenticationFailedException {
if (Arrays.equals(PKI_ALGO_ID_DER_BYTES_RSA_SHA1, signAlgoBytes)) {
return SIGNATURE_ALGO_RSA_SHA1;
} else if (Arrays.equals(PKI_ALGO_ID_DER_BYTES_RSA_SHA2_256, signAlgoBytes)) {
return SIGNATURE_ALGO_RSA_SHA2_256;
} else if (Arrays.equals(PKI_ALGO_ID_DER_BYTES_RSA_SHA2_384, signAlgoBytes)) {
return SIGNATURE_ALGO_RSA_SHA2_384;
} else if (Arrays.equals(PKI_ALGO_ID_DER_BYTES_RSA_SHA2_512, signAlgoBytes)) {
return SIGNATURE_ALGO_RSA_SHA2_512;
} else {
throw new AuthenticationFailedException(
"Unrecognized ASN.1 objects for Signature algorithm and Hash");
}
}
// TODO: Add methods for generating and validating signature.
@Override
protected void encodeAuthDataToByteBuffer(ByteBuffer byteBuffer) {
// TODO: Implement it.
throw new UnsupportedOperationException(
"It is not supported to encode a " + getTypeString());
}
@Override
protected int getAuthDataLength() {
// TODO: Implement it.
throw new UnsupportedOperationException(
"It is not supported to get payload length of " + getTypeString());
}
@Override
public String getTypeString() {
return "Authentication-Digital-Signature Payload";
}
}
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