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 2016-12-04
040 */
041@ThreadSafe
042public class RSA_OAEP {
043
044
045        /**
046         * Encrypts the specified Content Encryption Key (CEK).
047         *
048         * @param pub      The public RSA key. Must not be {@code null}.
049         * @param cek      The Content Encryption Key (CEK) to encrypt. Must
050         *                 not be {@code null}.
051         * @param provider The JCA provider, or {@code null} to use the default
052         *                 one.
053         *
054         * @return The encrypted Content Encryption Key (CEK).
055         *
056         * @throws JOSEException If encryption failed.
057         */
058        public static byte[] encryptCEK(final RSAPublicKey pub, final SecretKey cek, final Provider provider)
059                throws JOSEException {
060
061                try {
062                        Cipher cipher = CipherHelper.getInstance("RSA/ECB/OAEPWithSHA-1AndMGF1Padding", provider);
063                        cipher.init(Cipher.ENCRYPT_MODE, pub, new SecureRandom());
064                        return cipher.doFinal(cek.getEncoded());
065                        
066                } catch (IllegalBlockSizeException e) {
067                        throw new JOSEException("RSA block size exception: The RSA key is too short, try a longer one", e);
068                } catch (Exception e) {
069                        // java.security.NoSuchAlgorithmException
070                        // java.security.NoSuchPaddingException
071                        // java.security.InvalidKeyException
072                        // javax.crypto.BadPaddingException
073                        throw new JOSEException(e.getMessage(), e);
074                }
075        }
076
077        
078        /**
079         * Decrypts the specified encrypted Content Encryption Key (CEK).
080         *
081         * @param priv         The private RSA key. Must not be {@code null}.
082         * @param encryptedCEK The encrypted Content Encryption Key (CEK) to
083         *                     decrypt. Must not be {@code null}.
084         * @param provider     The JCA provider, or {@code null} to use the
085         *                     default one.
086         *
087         * @return The decrypted Content Encryption Key (CEK).
088         *
089         * @throws JOSEException If decryption failed.
090         */
091        public static SecretKey decryptCEK(final PrivateKey priv,
092                                           final byte[] encryptedCEK, final Provider provider)
093                throws JOSEException {
094
095                try {
096                        Cipher cipher = CipherHelper.getInstance("RSA/ECB/OAEPWithSHA1AndMGF1Padding", provider);
097                        cipher.init(Cipher.DECRYPT_MODE, priv);
098                        return new SecretKeySpec(cipher.doFinal(encryptedCEK), "AES");
099
100                } catch (Exception e) {
101                        // java.security.NoSuchAlgorithmException
102                        // java.security.NoSuchPaddingException
103                        // java.security.InvalidKeyException
104                        // javax.crypto.IllegalBlockSizeException
105                        // javax.crypto.BadPaddingException
106                        throw new JOSEException(e.getMessage(), e);
107                }
108        }
109
110
111        /**
112         * Prevents public instantiation.
113         */
114        private RSA_OAEP() { }
115}