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KSI Java SDK common module
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/*
 * Copyright 2013-2016 Guardtime, Inc.
 *
 * This file is part of the Guardtime client SDK.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES, CONDITIONS, OR OTHER LICENSES OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 * "Guardtime" and "KSI" are trademarks or registered trademarks of
 * Guardtime, Inc., and no license to trademarks is granted; Guardtime
 * reserves and retains all trademark rights.
 */
package com.guardtime.ksi.util;

/**
 * RFC 4648
 * base-32 encoding/decoding.
 *
 * @since 0.3
 */
public final class Base32 {

    /**
     * The encoder/decoder instance.
     */
    private static BaseX inst = new BaseX("ABCDEFGHIJKLMNOPQRSTUVWXYZ234567", false, '=');

    /**
     * Encodes the given bytes into a base-32 string.
     *
     * @param in
     *            the bytes to encode.
     * @return the base-32 string, or {@code null} if {@code in} is {@code null}.
     */
    public static String encode(byte[] in) {
        if (in == null) {
            return null;
        }
        return encode(in, 0, in.length);
    }

    /**
     * Encodes the given bytes into a base-32 string.
     *
     * @param in
     *            an array containing the bytes to encode.
     * @param off
     *            the start offset of the data within {@code in}.
     * @param len
     *            the number of bytes to encode.
     * @return the base-32 string.
     */
    public static String encode(byte[] in, int off, int len) {
        return inst.encode(in, off, len, null, 0).toString();
    }

    /**
     * Encodes the given bytes into a base-32 string, inserting dashes after
     * every 6 characters of output.
     *
     * @param in
     *            the bytes to encode.
     * @return the formatted base-32 string, or {@code null} if {@code in} is {@code null}.
     */
    public static String encodeWithDashes(byte[] in) {
        if (in == null) {
            return null;
        }
        return encodeWithDashes(in, 0, in.length);
    }

    /**
     * Encodes the given bytes into a base-32 string, inserting dashes after
     * every 6 characters of output.
     *
     * @param in
     *            the bytes to encode.
     * @param off
     *            the start offset of the data within {@code in}.
     * @param len
     *            the number of bytes to encode.
     * @return the formatted base-32 string.
     */
    public static String encodeWithDashes(byte[] in, int off, int len) {
        return inst.encode(in, off, len, "-", 6).toString();
    }

    /**
     * Decodes the given base-32 string into bytes. Any non-base-32 characters
     * are silently ignored.
     *
     * @param in
     *            the base-32 string to decode.
     * @return the decoded bytes, or {@code null} if {@code in} is {@code null}.
     */
    public static byte[] decode(String in) {
        if (in == null) {
            return null;
        }
        return inst.decode(in);
    }

    /**
     * This class should not be instantiated.
     */
    private Base32() {
    }

}