001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.codec.binary;
019
020import java.io.InputStream;
021
022/**
023 * Provides Base58 decoding in a streaming fashion (unlimited size). When encoding the default lineLength is 76 characters and the default lineEnding is CRLF,
024 * but these can be overridden by using the appropriate constructor.
025 * <p>
026 * The default behavior of the Base58InputStream is to DECODE, whereas the default behavior of the Base58OutputStream is to ENCODE, but this behavior can be
027 * overridden by using a different constructor.
028 * </p>
029 * <p>
030 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are
031 * compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
032 * </p>
033 * <p>
034 * You can set the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a valid encoding. These can be bits that are
035 * unused from the final character or entire characters. The default mode is lenient decoding.
036 * </p>
037 * <ul>
038 * <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.</li>
039 * <li>Strict: The decoding will throw an {@link IllegalArgumentException} if trailing bits are not part of a valid encoding. Any unused bits from the final
040 * character must be zero. Impossible counts of entire final characters are not allowed.</li>
041 * </ul>
042 * <p>
043 * When strict decoding is enabled it is expected that the decoded bytes will be re-encoded to a byte array that matches the original, i.e. no changes occur on
044 * the final character. This requires that the input bytes use the same padding and alphabet as the encoder.
045 * </p>
046 *
047 * @see Base58
048 * @see <a href="https://datatracker.ietf.org/doc/html/draft-msporny-base58-03">The Base58 Encoding Scheme draft-msporny-base58-03</a>
049 * @since 1.22.0
050 */
051public class Base58InputStream extends BaseNCodecInputStream<Base58, Base58InputStream, Base58InputStream.Builder> {
052
053    /**
054     * Builds instances of Base58InputStream.
055     */
056    public static class Builder extends BaseNCodecInputStream.AbstracBuilder<Base58InputStream, Base58, Builder> {
057
058        /**
059         * Constructs a new instance.
060         */
061        public Builder() {
062            // empty
063        }
064
065        @Override
066        public Base58InputStream get() {
067            return new Base58InputStream(this);
068        }
069
070        @Override
071        protected Base58 newBaseNCodec() {
072            return new Base58();
073        }
074    }
075
076    /**
077     * Constructs a new Builder.
078     *
079     * @return a new Builder.
080     */
081    public static Builder builder() {
082        return new Builder();
083    }
084
085    private Base58InputStream(final Builder builder) {
086        super(builder);
087    }
088
089    /**
090     * Constructs a Base58InputStream such that all data read is Base58-decoded from the original provided InputStream.
091     *
092     * @param inputStream InputStream to wrap.
093     */
094    public Base58InputStream(final InputStream inputStream) {
095        super(builder().setInputStream(inputStream));
096    }
097}