/*
 * Copyright (C) 2017 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 libcore.javax.crypto.spec;

import java.security.AlgorithmParameters;
import java.security.NoSuchAlgorithmException;
import java.security.Provider;
import java.security.Security;
import java.util.Arrays;
import java.util.Base64;
import javax.crypto.spec.GCMParameterSpec;

import tests.security.AlgorithmParameterSymmetricHelper;
import tests.security.AlgorithmParametersTest;

public class AlgorithmParametersTestGCM extends AlgorithmParametersTest {

    private static final byte[] IV = new byte[] {
        (byte) 0x04, (byte) 0x08, (byte) 0x68, (byte) 0xC8,
        (byte) 0xFF, (byte) 0x64, (byte) 0x72, (byte) 0xF5,
        (byte) 0x04, (byte) 0x08, (byte) 0x68, (byte) 0xC8 };

    private static final int TLEN = 96;

    // The ASN.1 encoding for GCM params (specified in RFC 5084 section 3.2) specifies
    // a default value of 12 for TLEN, so both values with and without TLEN should work.
    // See README.ASN1 for how to understand and reproduce this data.

    // asn1=SEQUENCE:gcm
    // [gcm]
    // iv=FORMAT:HEX,OCTETSTRING:040868C8FF6472F5040868C8
    private static final String ENCODED_DATA_NO_TLEN = "MA4EDAQIaMj/ZHL1BAhoyA==";

    // asn1=SEQUENCE:gcm
    // [gcm]
    // iv=FORMAT:HEX,OCTETSTRING:040868C8FF6472F5040868C8
    // tlen=INT:12
    private static final String ENCODED_DATA_TLEN = "MBEEDAQIaMj/ZHL1BAhoyAIBDA==";

    public AlgorithmParametersTestGCM() {
        super("GCM", new AlgorithmParameterSymmetricHelper("AES", "GCM/NOPADDING", 128), new GCMParameterSpec(TLEN, IV));
    }

    public void testEncoding() throws Exception {
        for (Provider p : Security.getProviders()) {
            AlgorithmParameters params;
            try {
                params = AlgorithmParameters.getInstance("GCM", p);
            } catch (NoSuchAlgorithmException e) {
                // This provider doesn't support AES/GCM, ignore
                continue;
            }

            params.init(new GCMParameterSpec(TLEN, IV));
            String encoded = Base64.getEncoder().encodeToString(params.getEncoded());
            assertTrue("Provider: " + p.getName() + ", encoded: " + encoded,
                    encoded.equals(ENCODED_DATA_TLEN) || encoded.equals(ENCODED_DATA_NO_TLEN));

            params = AlgorithmParameters.getInstance("GCM", p);
            params.init(Base64.getDecoder().decode(ENCODED_DATA_NO_TLEN));
            GCMParameterSpec spec = params.getParameterSpec(GCMParameterSpec.class);
            assertEquals("Provider: " + p.getName(), TLEN, spec.getTLen());
            assertTrue("Provider: " + p.getName(), Arrays.equals(IV, spec.getIV()));

            params = AlgorithmParameters.getInstance("GCM", p);
            params.init(Base64.getDecoder().decode(ENCODED_DATA_TLEN));
            spec = params.getParameterSpec(GCMParameterSpec.class);
            assertEquals("Provider: " + p.getName(), TLEN, spec.getTLen());
            assertTrue("Provider: " + p.getName(), Arrays.equals(IV, spec.getIV()));
        }
    }

}