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 com.nimbusds.jose.CompressionAlgorithm; 022import com.nimbusds.jose.JOSEException; 023import com.nimbusds.jose.JWEHeader; 024import com.nimbusds.jose.util.DeflateUtils; 025import net.jcip.annotations.ThreadSafe; 026 027 028/** 029 * Deflate (RFC 1951) helper methods, intended for use by JWE encrypters and 030 * decrypters. This class is thread-safe. 031 * 032 * @author Vladimir Dzhuvinov 033 * @version 2014-07-08 034 */ 035@ThreadSafe 036public class DeflateHelper { 037 038 039 /** 040 * Applies compression to the specified plain text if requested. 041 * 042 * @param jweHeader The JWE header. Must not be {@code null}. 043 * @param bytes The plain text bytes. Must not be {@code null}. 044 * 045 * @return The bytes to encrypt. 046 * 047 * @throws JOSEException If compression failed or the requested 048 * compression algorithm is not supported. 049 */ 050 public static byte[] applyCompression(final JWEHeader jweHeader, final byte[] bytes) 051 throws JOSEException { 052 053 CompressionAlgorithm compressionAlg = jweHeader.getCompressionAlgorithm(); 054 055 if (compressionAlg == null) { 056 057 return bytes; 058 059 } else if (compressionAlg.equals(CompressionAlgorithm.DEF)) { 060 061 try { 062 return DeflateUtils.compress(bytes); 063 064 } catch (Exception e) { 065 066 throw new JOSEException("Couldn't compress plain text: " + e.getMessage(), e); 067 } 068 069 } else { 070 071 throw new JOSEException("Unsupported compression algorithm: " + compressionAlg); 072 } 073 } 074 075 076 /** 077 * Applies decompression to the specified plain text if requested. 078 * 079 * @param jweHeader The JWE header. Must not be {@code null}. 080 * @param bytes The plain text bytes. Must not be {@code null}. 081 * 082 * @return The output bytes, decompressed if requested. 083 * 084 * @throws JOSEException If decompression failed or the requested 085 * compression algorithm is not supported. 086 */ 087 public static byte[] applyDecompression(final JWEHeader jweHeader, final byte[] bytes) 088 throws JOSEException { 089 090 CompressionAlgorithm compressionAlg = jweHeader.getCompressionAlgorithm(); 091 092 if (compressionAlg == null) { 093 094 return bytes; 095 096 } else if (compressionAlg.equals(CompressionAlgorithm.DEF)) { 097 098 try { 099 return DeflateUtils.decompress(bytes); 100 101 } catch (Exception e) { 102 103 throw new JOSEException("Couldn't decompress plain text: " + e.getMessage(), e); 104 } 105 106 } else { 107 108 throw new JOSEException("Unsupported compression algorithm: " + compressionAlg); 109 } 110 } 111}