/*
 * nimbus-jose-jwt
 *
 * Copyright 2012-2016, Connect2id Ltd.
 *
 * 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.nimbusds.jose.crypto;


import com.nimbusds.jose.*;
import com.nimbusds.jose.crypto.impl.*;
import com.nimbusds.jose.util.Base64URL;
import com.nimbusds.jose.util.StandardCharset;
import net.jcip.annotations.ThreadSafe;

import javax.crypto.SecretKey;
import java.util.Set;


/**
 * Password-based decrypter of {@link com.nimbusds.jose.JWEObject JWE objects}.
 * Expects a password.
 *
 * <p>See RFC 7518
 * <a href="https://tools.ietf.org/html/rfc7518#section-4.8">section 4.8</a>
 * for more information.
 *
 * <p>This class is thread-safe.
 *
 * <p>Supports the following key management algorithms:
 *
 * <ul>
 *     <li>{@link com.nimbusds.jose.JWEAlgorithm#PBES2_HS256_A128KW}
 *     <li>{@link com.nimbusds.jose.JWEAlgorithm#PBES2_HS384_A192KW}
 *     <li>{@link com.nimbusds.jose.JWEAlgorithm#PBES2_HS512_A256KW}
 * </ul>
 *
 * <p>Supports the following content encryption algorithms:
 *
 * <ul>
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A192CBC_HS384}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A128GCM}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A192GCM}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A256GCM}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256_DEPRECATED}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512_DEPRECATED}
 *     <li>{@link com.nimbusds.jose.EncryptionMethod#XC20P}
 * </ul>
 *
 * @author Vladimir Dzhuvinov
 * @author Egor Puzanov
 * @version 2024-09-10
 */
@ThreadSafe
public class PasswordBasedDecrypter extends PasswordBasedCryptoProvider implements JWEDecrypter, CriticalHeaderParamsAware {


        /**
         * The maximum allowed iteration count (1 million).
         */
        public static final int MAX_ALLOWED_ITERATION_COUNT = 1_000_000;


        /**
         * The critical header policy.
         */
        private final CriticalHeaderParamsDeferral critPolicy = new CriticalHeaderParamsDeferral();


        /**
         * Creates a new password-based decrypter.
         *
         * @param password The password bytes. Must not be empty or
         *                 {@code null}.
         */
        public PasswordBasedDecrypter(final byte[] password) {

                super(password);
        }


        /**
         * Creates a new password-based decrypter.
         *
         * @param password The password, as a UTF-8 encoded string. Must not be
         *                 empty or {@code null}.
         */
        public PasswordBasedDecrypter(final String password) {

                super(password.getBytes(StandardCharset.UTF_8));
        }


        @Override
        public Set<String> getProcessedCriticalHeaderParams() {

                return critPolicy.getProcessedCriticalHeaderParams();
        }


        @Override
        public Set<String> getDeferredCriticalHeaderParams() {

                return critPolicy.getProcessedCriticalHeaderParams();
        }


        /**
         * Decrypts the specified cipher text of a {@link JWEObject JWE Object}.
         *
         * @param header       The JSON Web Encryption (JWE) header. Must
         *                     specify a supported JWE algorithm and method.
         *                     Must not be {@code null}.
         * @param encryptedKey The encrypted key, {@code null} if not required
         *                     by the JWE algorithm.
         * @param iv           The initialisation vector, {@code null} if not
         *                     required by the JWE algorithm.
         * @param cipherText   The cipher text to decrypt. Must not be
         *                     {@code null}.
         * @param authTag      The authentication tag, {@code null} if not
         *                     required.
         *
         * @return The clear text.
         *
         * @throws JOSEException If the JWE algorithm or method is not
         *                       supported, if a critical header parameter is
         *                       not supported or marked for deferral to the
         *                       application, or if decryption failed for some
         *                       other reason.
         */
        @Deprecated
        public byte[] decrypt(final JWEHeader header,
                       final Base64URL encryptedKey,
                       final Base64URL iv,
                       final Base64URL cipherText,
                       final Base64URL authTag)
                throws JOSEException {

                return decrypt(header, encryptedKey, iv, cipherText, authTag, AAD.compute(header));
        }


        @Override
        public byte[] decrypt(final JWEHeader header,
                              final Base64URL encryptedKey,
                              final Base64URL iv,
                              final Base64URL cipherText,
                              final Base64URL authTag,
                              final byte[] aad)
                throws JOSEException {

                // Validate required JWE parts
                if (encryptedKey == null) {
                        throw new JOSEException("Missing JWE encrypted key");
                }

                if (iv == null) {
                        throw new JOSEException("Missing JWE initialization vector (IV)");
                }

                if (authTag == null) {
                        throw new JOSEException("Missing JWE authentication tag");
                }

                if (header.getPBES2Salt() == null) {
                        throw new JOSEException("Missing JWE p2s header parameter");
                }

                final byte[] salt = header.getPBES2Salt().decode();

                if (header.getPBES2Count() < 1) {
                        throw new JOSEException("Missing JWE p2c header parameter");
                }

                final int iterationCount = header.getPBES2Count();

                if (iterationCount > MAX_ALLOWED_ITERATION_COUNT) {
                        throw new JOSEException("The JWE p2c header exceeds the maximum allowed " + MAX_ALLOWED_ITERATION_COUNT + " count");
                }

                critPolicy.ensureHeaderPasses(header);

                final JWEAlgorithm alg = JWEHeaderValidation.getAlgorithmAndEnsureNotNull(header);
                final byte[] formattedSalt = PBKDF2.formatSalt(alg, salt);
                final PRFParams prfParams = PRFParams.resolve(alg, getJCAContext().getMACProvider());
                final SecretKey psKey = PBKDF2.deriveKey(getPassword(), formattedSalt, iterationCount, prfParams, getJCAContext().getProvider());

                final SecretKey cek = AESKW.unwrapCEK(psKey, encryptedKey.decode(), getJCAContext().getKeyEncryptionProvider());

                return ContentCryptoProvider.decrypt(header, aad, encryptedKey, iv, cipherText, authTag, cek, getJCAContext());
        }
}