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.interfaces.RSAPublicKey; 024import javax.crypto.Cipher; 025import javax.crypto.IllegalBlockSizeException; 026import javax.crypto.SecretKey; 027import javax.crypto.spec.SecretKeySpec; 028 029import com.nimbusds.jose.JOSEException; 030import com.nimbusds.jose.util.ByteUtils; 031import net.jcip.annotations.ThreadSafe; 032 033 034/** 035 * RSAES-PKCS1-V1_5 methods for Content Encryption Key (CEK) encryption and 036 * decryption. This class is thread-safe. 037 * 038 * @author Vladimir Dzhuvinov 039 * @version 2017-06-01 040 */ 041@ThreadSafe 042public class RSA1_5 { 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, Provider provider) 059 throws JOSEException { 060 061 try { 062 Cipher cipher = CipherHelper.getInstance("RSA/ECB/PKCS1Padding", provider); 063 cipher.init(Cipher.ENCRYPT_MODE, pub); 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.InvalidKeyException 071 throw new JOSEException("Couldn't encrypt Content Encryption Key (CEK): " + e.getMessage(), e); 072 } 073 } 074 075 076 /** 077 * Decrypts the specified encrypted Content Encryption Key (CEK). 078 * 079 * @param priv The private RSA key. Must not be {@code null}. 080 * @param encryptedCEK The encrypted Content Encryption Key (CEK) to 081 * decrypt. Must not be {@code null}. 082 * @param provider The JCA provider, or {@code null} to use the 083 * default one. 084 * 085 * @return The decrypted Content Encryption Key (CEK), {@code null} if 086 * there was a CEK key length mismatch. 087 * 088 * @throws JOSEException If decryption failed. 089 */ 090 public static SecretKey decryptCEK(final PrivateKey priv, 091 final byte[] encryptedCEK, 092 final int keyLength, 093 final Provider provider) 094 throws JOSEException { 095 096 try { 097 Cipher cipher = CipherHelper.getInstance("RSA/ECB/PKCS1Padding", provider); 098 cipher.init(Cipher.DECRYPT_MODE, priv); 099 byte[] secretKeyBytes = cipher.doFinal(encryptedCEK); 100 101 if (ByteUtils.safeBitLength(secretKeyBytes) != keyLength) { 102 // CEK key length mismatch 103 return null; 104 } 105 106 return new SecretKeySpec(secretKeyBytes, "AES"); 107 108 } catch (Exception e) { 109 110 // java.security.NoSuchAlgorithmException 111 // java.security.InvalidKeyException 112 // javax.crypto.IllegalBlockSizeException 113 // javax.crypto.BadPaddingException 114 throw new JOSEException("Couldn't decrypt Content Encryption Key (CEK): " + e.getMessage(), e); 115 } 116 } 117 118 119 /** 120 * Prevents public instantiation. 121 */ 122 private RSA1_5() { } 123}