net.pwall.util.Base64 Maven / Gradle / Ivy
/*
* @(#) Base64.java
*
* javautil Java Utility Library
* Copyright (c) 2017 Peter Wall
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package net.pwall.util;
import java.io.IOException;
/**
* Encode and decode Base64. This functionality exists in a variety of other libraries, but
* those libraries generally include a lot of other unneeded code.
*
* @author Peter Wall
*/
public class Base64 {
private static final byte[] base64Bytes = new byte[64];
private static final byte[] base64URLBytes = new byte[64];
private static final byte[] reverseBytes = new byte[128];
private static final byte[] emptyBytes = new byte[0];
static {
for (int i = 0; i < 128; i++)
reverseBytes[i] = (byte)0xFF;
for (int i = 0; i < 26; i++) {
base64Bytes[i] = (byte)('A' + i);
base64URLBytes[i] = (byte)('A' + i);
reverseBytes['A' + i] = (byte)i;
}
for (int i = 0; i < 26; i++) {
base64Bytes[i + 26] = (byte)('a' + i);
base64URLBytes[i + 26] = (byte)('a' + i);
reverseBytes['a' + i] = (byte)(i + 26);
}
for (int i = 0; i < 10; i++) {
base64Bytes[i + 52] = (byte)('0' + i);
base64URLBytes[i + 52] = (byte)('0' + i);
reverseBytes['0' + i] = (byte)(i + 52);
}
base64Bytes[62] = (byte)'+';
reverseBytes['+'] = (byte)62;
base64URLBytes[62] = (byte)'-';
reverseBytes['-'] = (byte)62;
base64Bytes[63] = (byte)'/';
reverseBytes['/'] = (byte)63;
base64URLBytes[63] = (byte)'_';
reverseBytes['_'] = (byte)63;
}
/**
* Private constructor - do not instantiate.
*/
private Base64() {
}
/**
* Get the encoded length of data encoded into Base64.
*
* @param n the source data length
* @return the encoded data length
* @throws NullPointerException if the data is null
*/
public static int getEncodedLength(int n) {
return (n + 2) / 3 * 4;
}
/**
* Get the encoded length of data encoded into the URL variant of Base64. This variant uses
* different characters for the last two positions in the encoding table, and (significantly
* for length calculation) it doesn't pad with equal signs.
*
* @param n the source data length
* @return the encoded data length
* @throws NullPointerException if the data is null
*/
public static int getEncodedURLLength(int n) {
return (n * 4 + 2) / 3;
}
/**
* Encode a byte array into Base64, returning another byte array.
*
* @param data the source data
* @return the encoded data
* @throws NullPointerException if the data is null
*/
public static byte[] encode(byte[] data) {
int n = data.length;
if (n == 0)
return emptyBytes;
byte[] bytes = new byte[getEncodedLength(n)];
int i = 0;
int x = 0;
int a, b, c;
int nm3 = n - 3;
while (i <= nm3) {
a = data[i++];
b = data[i++];
c = data[i++];
bytes[x++] = base64Bytes[(a >> 2) & 0x3F];
bytes[x++] = base64Bytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)];
bytes[x++] = base64Bytes[((b << 2) & 0x3C) | ((c >> 6) & 0x03)];
bytes[x++] = base64Bytes[c & 0x3F];
}
n -= i;
if (n > 0) {
a = data[i];
bytes[x++] = base64Bytes[(a >> 2) & 0x3F];
if (n == 1) {
bytes[x++] = base64Bytes[(a << 4) & 0x30];
bytes[x++] = '=';
bytes[x] = '=';
}
else {
b = data[i + 1];
bytes[x++] = base64Bytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)];
bytes[x++] = base64Bytes[(b << 2) & 0x3C];
bytes[x] = '=';
}
}
return bytes;
}
/**
* Encode a byte array into the URL variant of Base64, returning another byte array. The
* URL variant uses different characters for the last two positions in the encoding table,
* and it doesn't pad with equal signs.
*
* @param data the source data
* @return the encoded data
* @throws NullPointerException if the data is null
*/
public static byte[] encodeURL(byte[] data) {
int n = data.length;
if (n == 0)
return emptyBytes;
byte[] bytes = new byte[getEncodedURLLength(n)];
int i = 0;
int x = 0;
int a, b, c;
int nm3 = n - 3;
while (i <= nm3) {
a = data[i++];
b = data[i++];
c = data[i++];
bytes[x++] = base64URLBytes[(a >> 2) & 0x3F];
bytes[x++] = base64URLBytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)];
bytes[x++] = base64URLBytes[((b << 2) & 0x3C) | ((c >> 6) & 0x03)];
bytes[x++] = base64URLBytes[c & 0x3F];
}
n -= i;
if (n > 0) {
a = data[i];
bytes[x++] = base64URLBytes[(a >> 2) & 0x3F];
if (n == 1)
bytes[x++] = base64URLBytes[(a << 4) & 0x30];
else {
b = data[i + 1];
bytes[x++] = base64URLBytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)];
bytes[x++] = base64URLBytes[(b << 2) & 0x3C];
}
}
return bytes;
}
/**
* Append a byte array to an {@link Appendable} as Base64-encoded characters.
*
* @param app the {@link Appendable}
* @param data the source data
* @throws IOException if thrown by the {@link Appendable}
* @throws NullPointerException if the data is null
*/
public static void appendEncoded(Appendable app, byte[] data) throws IOException {
appendEncoded(app, data, 0, data.length);
}
/**
* Append a section of a byte array to an {@link Appendable} as Base64-encoded characters.
*
* @param app the {@link Appendable}
* @param data the source data
* @param start the start index of the data to be encoded
* @param end the end index
* @throws IOException if thrown by the {@link Appendable}
* @throws NullPointerException if the data is null
*/
public static void appendEncoded(Appendable app, byte[] data, int start, int end)
throws IOException {
int i = start;
int a, b, c;
int endm3 = end - 3;
while (i <= endm3) {
a = data[i++];
b = data[i++];
c = data[i++];
app.append((char)(base64Bytes[(a >> 2) & 0x3F])).
append((char)(base64Bytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)])).
append((char)(base64Bytes[((b << 2) & 0x3C) | ((c >> 6) & 0x03)])).
append((char)(base64Bytes[c & 0x3F]));
}
int n = end - i;
if (n > 0) {
a = data[i];
app.append((char)(base64Bytes[(a >> 2) & 0x3F]));
if (n == 1)
app.append((char)(base64Bytes[(a << 4) & 0x30])).append('=').append('=');
else {
b = data[i + 1];
app.append((char)(base64Bytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)])).
append((char)(base64Bytes[(b << 2) & 0x3C])).append('=');
}
}
}
/**
* Append a byte array to an {@link Appendable} as Base64-encoded characters, using the URL
* variant of Base64.
*
* @param app the {@link Appendable}
* @param data the source data
* @throws IOException if thrown by the {@link Appendable}
* @throws NullPointerException if the data is null
*/
public static void appendURLEncoded(Appendable app, byte[] data) throws IOException {
appendURLEncoded(app, data, 0, data.length);
}
/**
* Append a section of a byte array to an {@link Appendable} as Base64-encoded characters,
* using the URL variant of Base64.
*
* @param app the {@link Appendable}
* @param data the source data
* @param start the start index of the data to be encoded
* @param end the end index
* @throws IOException if thrown by the {@link Appendable}
* @throws NullPointerException if the data is null
*/
public static void appendURLEncoded(Appendable app, byte[] data, int start, int end)
throws IOException {
int i = start;
int a, b, c;
int endm3 = end - 3;
while (i <= endm3) {
a = data[i++];
b = data[i++];
c = data[i++];
app.append((char)(base64URLBytes[(a >> 2) & 0x3F])).
append((char)(base64URLBytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)])).
append((char)(base64URLBytes[((b << 2) & 0x3C) | ((c >> 6) & 0x03)])).
append((char)(base64URLBytes[c & 0x3F]));
}
int n = end - i;
if (n > 0) {
a = data[i];
app.append((char)(base64URLBytes[(a >> 2) & 0x3F]));
if (n == 1)
app.append((char)(base64URLBytes[(a << 4) & 0x30]));
else {
b = data[i + 1];
app.append((char)(base64URLBytes[((a << 4) & 0x30) | ((b >> 4) & 0x0F)])).
append((char)(base64URLBytes[(b << 2) & 0x3C]));
}
}
}
/**
* Encode a byte array into Base64, returning a string.
*
* @param data the source data
* @return the encoded string
* @throws NullPointerException if the data is null
*/
public String encodeString(byte[] data) {
StringBuilder sb = new StringBuilder(getEncodedLength(data.length));
try {
appendEncoded(sb, data);
}
catch (IOException e) {
// can't happen - StringBuilder.append() does not throw IOException
}
return sb.toString();
}
/**
* Encode a byte array into the URL variant of Base64, returning a string. The URL variant
* uses different characters for the last two positions in the encoding table, and it
* doesn't pad with equal signs.
*
* @param data the source data
* @return the encoded data
* @throws NullPointerException if the data is null
*/
public String encodeStringURL(byte[] data) {
StringBuilder sb = new StringBuilder(getEncodedURLLength(data.length));
try {
appendURLEncoded(sb, data);
}
catch (IOException e) {
// can't happen - StringBuilder.append() does not throw IOException
}
return sb.toString();
}
/**
* Decode a byte array from Base64. Both the original and the URL variants are handled.
*
* @param data the source data
* @return the decoded data
* @throws IllegalArgumentException if the data is not valid Base64
* @throws NullPointerException if the data is null
*/
public static byte[] decode(byte[] data) {
int n = data.length;
if (n == 0)
return emptyBytes;
if ((n & 3) == 0) { // length divisible by 4 - could have trailing = sign(s)
if (data[n - 1] == '='){
n--;
if (data[n - 1] == '=')
n--;
}
}
else { // otherwise length can't be 1, 5, 9, 13 ...
if ((n & 3) == 1)
throw new IllegalArgumentException("Incorrect number of bytes for Base64");
}
byte[] bytes = new byte[(n * 3) >> 2];
int x = 0;
int i = 0;
int a, b, c, d;
int nm4 = n - 4;
while (i <= nm4) {
a = decodeByte(data[i++]);
b = decodeByte(data[i++]);
c = decodeByte(data[i++]);
d = decodeByte(data[i++]);
bytes[x++] = (byte)(((a << 2) & 0xFC) | ((b >> 4) & 0x03));
bytes[x++] = (byte)(((b << 4) & 0xF0) | ((c >> 2) & 0xF));
bytes[x++] = (byte)(((c << 6) & 0xC0) | d);
}
n -= i;
if (n > 0) {
a = decodeByte(data[i]);
b = decodeByte(data[i + 1]);
bytes[x++] = (byte)(((a << 2) & 0xFC) | ((b >> 4) & 0x03));
if (n == 2) {
if ((b & 0xF) != 0)
throw new IllegalArgumentException("Illegal character in Base64");
}
else {
c = decodeByte(data[i + 2]);
bytes[x++] = (byte)(((b << 4) & 0xF0) | ((c >> 2) & 0xF));
if ((c & 3) != 0)
throw new IllegalArgumentException("Illegal character in Base64");
}
}
return bytes;
}
/**
* Decode a {@link CharSequence} ({@link String}, {@link StringBuilder} etc.) from Base64.
* Both the original and the URL variants are handled.
*
* @param data the source data
* @return the decoded data
* @throws IllegalArgumentException if the data is not valid Base64
* @throws NullPointerException if the data is null
*/
public static byte[] decode(CharSequence data) {
int n = data.length();
if (n == 0)
return emptyBytes;
if ((n & 3) == 0) { // length divisible by 4 - could have trailing = sign(s)
if (data.charAt(n - 1) == '='){
n--;
if (data.charAt(n - 1) == '=')
n--;
}
}
else { // otherwise length can't be 1, 5, 9, 13 ...
if ((n & 3) == 1)
throw new IllegalArgumentException("Incorrect number of bytes for Base64");
}
byte[] bytes = new byte[(n * 3) >> 2];
int x = 0;
int i = 0;
int a, b, c, d;
int nm4 = n - 4;
while (i <= nm4) {
a = decodeByte(data.charAt(i++));
b = decodeByte(data.charAt(i++));
c = decodeByte(data.charAt(i++));
d = decodeByte(data.charAt(i++));
bytes[x++] = (byte)(((a << 2) & 0xFC) | ((b >> 4) & 0x03));
bytes[x++] = (byte)(((b << 4) & 0xF0) | ((c >> 2) & 0xF));
bytes[x++] = (byte)(((c << 6) & 0xC0) | d);
}
n -= i;
if (n > 0) {
a = decodeByte(data.charAt(i));
b = decodeByte(data.charAt(i + 1));
bytes[x++] = (byte)(((a << 2) & 0xFC) | ((b >> 4) & 0x03));
if (n == 2) {
if ((b & 0xF) != 0)
throw new IllegalArgumentException("Illegal character in Base64");
}
else {
c = decodeByte(data.charAt(i + 2));
bytes[x++] = (byte)(((b << 4) & 0xF0) | ((c >> 2) & 0xF));
if ((c & 3) != 0)
throw new IllegalArgumentException("Illegal character in Base64");
}
}
return bytes;
}
private static int decodeByte(int b) {
if ((b & ~0x7F) == 0) {
byte result = reverseBytes[b];
if ((result & ~0x3F) == 0)
return result;
}
throw new IllegalArgumentException("Illegal character in Base64");
}
}
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