001/*
002 * nimbus-jose-jwt
003 *
004 * Copyright 2012-2016, Connect2id Ltd and contributors.
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use
007 * this file except in compliance with the License. You may obtain a copy of the
008 * License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software distributed
013 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
014 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
015 * specific language governing permissions and limitations under the License.
016 */
017
018package com.nimbusds.jose.crypto.impl;
019
020
021import java.security.PrivateKey;
022import java.security.Provider;
023import java.security.SecureRandom;
024import java.security.interfaces.RSAPublicKey;
025import javax.crypto.Cipher;
026import javax.crypto.IllegalBlockSizeException;
027import javax.crypto.SecretKey;
028import javax.crypto.spec.SecretKeySpec;
029
030import com.nimbusds.jose.JOSEException;
031import net.jcip.annotations.ThreadSafe;
032
033
034/**
035 * RSAES OAEP methods for Content Encryption Key (CEK) encryption and 
036 * decryption. Uses the BouncyCastle.org provider. This class is thread-safe
037 *
038 * @author Vladimir Dzhuvinov
039 * @version 2017-11-27
040 */
041@ThreadSafe
042public class RSA_OAEP {
043        
044        
045        /**
046         * The JCA algorithm name for RSA-OAEP.
047         */
048        private static final String RSA_OEAP_JCA_ALG = "RSA/ECB/OAEPWithSHA-1AndMGF1Padding";
049
050
051        /**
052         * Encrypts the specified Content Encryption Key (CEK).
053         *
054         * @param pub      The public RSA key. Must not be {@code null}.
055         * @param cek      The Content Encryption Key (CEK) to encrypt. Must
056         *                 not be {@code null}.
057         * @param provider The JCA provider, {@code null} to use the default.
058         *
059         * @return The encrypted Content Encryption Key (CEK).
060         *
061         * @throws JOSEException If encryption failed.
062         */
063        public static byte[] encryptCEK(final RSAPublicKey pub, final SecretKey cek, final Provider provider)
064                throws JOSEException {
065
066                try {
067                        Cipher cipher = CipherHelper.getInstance(RSA_OEAP_JCA_ALG, provider);
068                        cipher.init(Cipher.ENCRYPT_MODE, pub, new SecureRandom());
069                        return cipher.doFinal(cek.getEncoded());
070                        
071                } catch (IllegalBlockSizeException e) {
072                        throw new JOSEException("RSA block size exception: The RSA key is too short, try a longer one", e);
073                } catch (Exception e) {
074                        // java.security.NoSuchAlgorithmException
075                        // java.security.NoSuchPaddingException
076                        // java.security.InvalidKeyException
077                        // javax.crypto.BadPaddingException
078                        throw new JOSEException(e.getMessage(), e);
079                }
080        }
081
082        
083        /**
084         * Decrypts the specified encrypted Content Encryption Key (CEK).
085         *
086         * @param priv         The private RSA key. Must not be {@code null}.
087         * @param encryptedCEK The encrypted Content Encryption Key (CEK) to
088         *                     decrypt. Must not be {@code null}.
089         * @param provider     The JCA provider, {@code null} to use the
090         *                     default.
091         *
092         * @return The decrypted Content Encryption Key (CEK).
093         *
094         * @throws JOSEException If decryption failed.
095         */
096        public static SecretKey decryptCEK(final PrivateKey priv,
097                                           final byte[] encryptedCEK, final Provider provider)
098                throws JOSEException {
099
100                try {
101                        Cipher cipher = CipherHelper.getInstance(RSA_OEAP_JCA_ALG, provider);
102                        cipher.init(Cipher.DECRYPT_MODE, priv);
103                        return new SecretKeySpec(cipher.doFinal(encryptedCEK), "AES");
104
105                } catch (Exception e) {
106                        // java.security.NoSuchAlgorithmException
107                        // java.security.NoSuchPaddingException
108                        // java.security.InvalidKeyException
109                        // javax.crypto.IllegalBlockSizeException
110                        // javax.crypto.BadPaddingException
111                        throw new JOSEException(e.getMessage(), e);
112                }
113        }
114
115
116        /**
117         * Prevents public instantiation.
118         */
119        private RSA_OAEP() { }
120}