001/* 002 * Licensed to DuraSpace under one or more contributor license agreements. 003 * See the NOTICE file distributed with this work for additional information 004 * regarding copyright ownership. 005 * 006 * DuraSpace licenses this file to you under the Apache License, 007 * Version 2.0 (the "License"); you may not use this file except in 008 * compliance with the License. You may obtain a copy of the 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 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.fcrepo.kernel.api.utils; 019 020import static org.apache.commons.codec.binary.Hex.encodeHexString; 021import static org.fcrepo.kernel.api.utils.ContentDigest.DIGEST_ALGORITHM.SHA1; 022import static org.slf4j.LoggerFactory.getLogger; 023 024import java.net.URI; 025import java.net.URISyntaxException; 026import java.util.Arrays; 027 028import org.fcrepo.kernel.api.exception.RepositoryRuntimeException; 029import org.slf4j.Logger; 030 031/** 032 * Digest helpers to convert digests (checksums) into URI strings 033 * (based loosely on Magnet URIs) 034 * @author Chris Beer 035 * @since Mar 6, 2013 036 */ 037public final class ContentDigest { 038 039 private static final Logger LOGGER = getLogger(ContentDigest.class); 040 041 public enum DIGEST_ALGORITHM { 042 SHA1("SHA", "urn:sha1"), SHA256("SHA-256", "urn:sha-256"), MD5("MD5", "urn:md5"), MISSING("NONE", "missing"); 043 044 final public String algorithm; 045 final private String scheme; 046 047 DIGEST_ALGORITHM(final String alg, final String scheme) { 048 this.algorithm = alg; 049 this.scheme = scheme; 050 } 051 052 /** 053 * Return the scheme associated with the provided algorithm (e.g. SHA-1 returns urn:sha1) 054 * 055 * @param alg for which scheme is requested 056 * @return scheme 057 */ 058 public static String getScheme(final String alg) { 059 return Arrays.stream(values()).filter(value -> 060 value.algorithm.equalsIgnoreCase(alg) || value.algorithm.replace("-", "").equalsIgnoreCase(alg) 061 ).findFirst().orElse(MISSING).scheme; 062 } 063 064 /** 065 * Return enum value for the provided scheme (e.g. urn:sha1 returns SHA-1) 066 * 067 * @param argScheme for which enum is requested 068 * @return enum value associated with the arg scheme 069 */ 070 public static DIGEST_ALGORITHM fromScheme(final String argScheme) { 071 return Arrays.stream(values()).filter(value -> value.scheme.equalsIgnoreCase(argScheme) 072 ).findFirst().orElse(MISSING); 073 } 074 075 /** 076 * Return true if the provided algorithm is included in this enum 077 * 078 * @param alg to test 079 * @return true if arg algorithm is supported 080 */ 081 public static boolean isSupportedAlgorithm(final String alg) { 082 return !getScheme(alg).equals(MISSING.scheme); 083 } 084 } 085 086 public static final String DEFAULT_ALGORITHM = DIGEST_ALGORITHM.SHA1.algorithm; 087 088 private ContentDigest() { 089 } 090 091 /** 092 * Convert a MessageDigest algorithm and checksum value to a URN 093 * @param algorithm the message digest algorithm 094 * @param value the checksum value 095 * @return URI 096 */ 097 public static URI asURI(final String algorithm, final String value) { 098 try { 099 final String scheme = DIGEST_ALGORITHM.getScheme(algorithm); 100 101 return new URI(scheme, value, null); 102 } catch (final URISyntaxException unlikelyException) { 103 LOGGER.warn("Exception creating checksum URI: {}", 104 unlikelyException); 105 throw new RepositoryRuntimeException(unlikelyException); 106 } 107 } 108 109 /** 110 * Convert a MessageDigest algorithm and checksum byte-array data to a URN 111 * @param algorithm the message digest algorithm 112 * @param data the checksum byte-array data 113 * @return URI 114 */ 115 public static URI asURI(final String algorithm, final byte[] data) { 116 return asURI(algorithm, asString(data)); 117 } 118 119 /** 120 * Given a digest URI, get the corresponding MessageDigest algorithm 121 * @param digestUri the digest uri 122 * @return MessageDigest algorithm 123 */ 124 public static String getAlgorithm(final URI digestUri) { 125 if (digestUri == null) { 126 return DEFAULT_ALGORITHM; 127 } 128 return DIGEST_ALGORITHM.fromScheme(digestUri.getScheme() + ":" + 129 digestUri.getSchemeSpecificPart().split(":", 2)[0]).algorithm; 130 } 131 132 private static String asString(final byte[] data) { 133 return encodeHexString(data); 134 } 135 136 /** 137 * Placeholder checksum value. 138 * @return URI 139 */ 140 public static URI missingChecksum() { 141 return asURI(SHA1.algorithm, SHA1.scheme); 142 } 143 144}