Base64.java
/*
* The contents of this file are subject to the terms of the Common Development and
* Distribution License (the License). You may not use this file except in compliance with the
* License.
*
* You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
* specific language governing permission and limitations under the License.
*
* When distributing Covered Software, include this CDDL Header Notice in each file and include
* the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
* Header, with the fields enclosed by brackets [] replaced by your own identifying
* information: "Portions copyright [year] [name of copyright owner]".
*
* Copyright 2015-2016 ForgeRock AS.
*/
package org.forgerock.util.encode;
import java.util.Arrays;
/**
* A very fast and memory efficient class to encode and decode to and from
* BASE64 in full accordance with RFC 2045.<br>
* <br>
* On Windows XP sp1 with 1.4.2_04 and later ;), this encoder and decoder is
* about 10 times faster on small arrays (10 - 1000 bytes) and 2-3 times as fast
* on larger arrays (10000 - 1000000 bytes) compared to
* <code>sun.misc.Encoder()/Decoder()</code>.<br>
* <br>
* On byte arrays the encoder is about 20% faster than Jakarta Commons Base64
* Codec for encode and about 50% faster for decoding large arrays. This
* implementation is about twice as fast on very small arrays (< 30 bytes).
* If source/destination is a <code>String</code> this version is about three
* times as fast due to the fact that the Commons Codec result has to be recoded
* to a <code>String</code> from <code>byte[]</code>, which is very expensive.<br>
* <br>
* This encode/decode algorithm doesn't create any temporary arrays as many
* other codecs do, it only allocates the resulting array. This produces less
* garbage and it is possible to handle arrays twice as large as algorithms that
* create a temporary array. (E.g. Jakarta Commons Codec). It is unknown whether
* Sun's <code>sun.misc.Encoder()/Decoder()</code> produce temporary arrays but
* since performance is quite low it probably does.<br>
* <br>
* The encoder produces the same output as the Sun one except that the Sun's
* encoder appends a trailing line separator if the last character isn't a pad.
* Unclear why but it only adds to the length and is probably a side effect.
* Both are in conformance with RFC 2045 though.<br>
* Commons codec seem to always att a trailing line separator.<br>
* <br>
* <b>Note!</b> The encode/decode method pairs (types) come in three versions
* with the <b>exact</b> same algorithm and thus a lot of code redundancy. This
* is to not create any temporary arrays for transcoding to/from different
* format types. The methods not used can simply be commented out.<br>
* <br>
* There is also a "fast" version of all decode methods that works the same way
* as the normal ones, but har a few demands on the decoded input. Normally
* though, these fast verions should be used if the source if the input is known
* and it hasn't bee tampered with.<br>
* <br>
* If you find the code useful or you find a bug, please send me a note at
* base64 @ miginfocom . com.
*
* @version 2.2
*/
public final class Base64 {
private static final char[] CA =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
private static final int[] IA = new int[256];
static {
Arrays.fill(IA, -1);
for (int i = 0, iS = CA.length; i < iS; i++) {
IA[CA[i]] = i;
}
IA['='] = 0;
}
/**
* Decodes a BASE64 encoded byte array. All illegal characters will be
* ignored and can handle both arrays with and without line separators.
*
* @param sArr
* The source array. Length 0 will return an empty array.
* <code>null</code> will throw an exception.
* @return The decoded array of bytes. May be of length 0. Will be
* <code>null</code> if the legal characters (including '=') isn't
* divideable by 4. (I.e. definitely corrupted).
*/
public static byte[] decode(final byte[] sArr) {
// Check special case
final int sLen = sArr.length;
/*
* Count illegal characters (including '\r', '\n') to know what size the
* returned array will be, so we don't have to reallocate & copy it
* later.
*/
int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)
// If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be removed.
for (byte aSArr : sArr) {
if (IA[aSArr & 0xff] < 0) {
sepCnt++;
}
}
/*
* Check so that legal chars (including '=') are evenly divideable by 4
* as specified in RFC 2045.
*/
if ((sLen - sepCnt) % 4 != 0) {
return null;
}
int pad = 0;
for (int i = sLen; i > 1 && IA[sArr[--i] & 0xff] <= 0;) {
if (sArr[i] == '=') {
pad++;
}
}
final int len = ((sLen - sepCnt) * 6 >> 3) - pad;
final byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
for (int s = 0, d = 0; d < len;) {
// Assemble three bytes into an int from four "valid" characters.
int i = 0;
for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
final int c = IA[sArr[s++] & 0xff];
if (c >= 0) {
i |= c << 18 - j * 6;
} else {
j--;
}
}
// Add the bytes
dArr[d++] = (byte) (i >> 16);
if (d < len) {
dArr[d++] = (byte) (i >> 8);
if (d < len) {
dArr[d++] = (byte) i;
}
}
}
return dArr;
}
/**
* Decodes a BASE64 encoded char array. All illegal characters will be
* ignored and can handle both arrays with and without line separators.
*
* @param sArr
* The source array. <code>null</code> or length 0 will return an
* empty array.
* @return The decoded array of bytes. May be of length 0. Will be
* <code>null</code> if the legal characters (including '=') isn't
* divideable by 4. (I.e. definitely corrupted).
*/
public static byte[] decode(final char[] sArr) {
// Check special case
final int sLen = sArr != null ? sArr.length : 0;
if (sLen == 0) {
return new byte[0];
}
/*
* Count illegal characters (including '\r', '\n') to know what size the
* returned array will be, so we don't have to reallocate & copy it
* later.
*/
// Number of separator characters. (Actually illegal characters, but that's a bonus...)
int sepCnt = 0;
// If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
for (int i = 0; i < sLen; i++) {
if (IA[sArr[i]] < 0) {
sepCnt++;
}
}
/*
* Check so that legal chars (including '=') are evenly divideable by 4
* as specified in RFC 2045.
*/
if ((sLen - sepCnt) % 4 != 0) {
return null;
}
int pad = 0;
for (int i = sLen; i > 1 && IA[sArr[--i]] <= 0;) {
if (sArr[i] == '=') {
pad++;
}
}
final int len = ((sLen - sepCnt) * 6 >> 3) - pad;
final byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
for (int s = 0, d = 0; d < len;) {
// Assemble three bytes into an int from four "valid" characters.
int i = 0;
for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
final int c = IA[sArr[s++]];
if (c >= 0) {
i |= c << 18 - j * 6;
} else {
j--;
}
}
// Add the bytes
dArr[d++] = (byte) (i >> 16);
if (d < len) {
dArr[d++] = (byte) (i >> 8);
if (d < len) {
dArr[d++] = (byte) i;
}
}
}
return dArr;
}
/**
* Decodes a BASE64 encoded <code>String</code>. All illegal characters will
* be ignored and can handle both strings with and without line separators.<br>
* <b>Note!</b> It can be up to about 2x the speed to call
* <code>decode(str.toCharArray())</code> instead. That will create a
* temporary array though. This version will use <code>str.charAt(i)</code>
* to iterate the string.
*
* @param str
* The source string. <code>null</code> or length 0 will return
* an empty array.
* @return The decoded array of bytes. May be of length 0. Will be
* <code>null</code> if the legal characters (including '=') isn't
* divideable by 4. (I.e. definitely corrupted).
*/
public static byte[] decode(final String str) {
// Check special case
final int sLen = str != null ? str.length() : 0;
if (sLen == 0) {
return new byte[0];
}
/*
* Count illegal characters (including '\r', '\n') to know what size the
* returned array will be, so we don't have to reallocate & copy it
* later.
*/
// Number of separator characters. (Actually illegal characters, but that's a bonus...)
int sepCnt = 0;
// If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
for (int i = 0; i < sLen; i++) {
if (IA[str.charAt(i)] < 0) {
sepCnt++;
}
}
/*
* Check so that legal chars (including '=') are evenly divideable by 4
* as specified in RFC 2045.
*/
if ((sLen - sepCnt) % 4 != 0) {
return null;
}
// Count '=' at end
int pad = 0;
for (int i = sLen; i > 1 && IA[str.charAt(--i)] <= 0;) {
if (str.charAt(i) == '=') {
pad++;
}
}
final int len = ((sLen - sepCnt) * 6 >> 3) - pad;
final byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
for (int s = 0, d = 0; d < len;) {
// Assemble three bytes into an int from four "valid" characters.
int i = 0;
for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
final int c = IA[str.charAt(s++)];
if (c >= 0) {
i |= c << 18 - j * 6;
} else {
j--;
}
}
// Add the bytes
dArr[d++] = (byte) (i >> 16);
if (d < len) {
dArr[d++] = (byte) (i >> 8);
if (d < len) {
dArr[d++] = (byte) i;
}
}
}
return dArr;
}
/**
* Decodes a BASE64 encoded byte array that is known to be resonably well
* formatted. The method is about twice as fast as {@link #decode(byte[])}.
* The preconditions are:<br>
* + The array must have a line length of 76 chars OR no line separators at
* all (one line).<br>
* + Line separator must be "\r\n", as specified in RFC 2045 + The array
* must not contain illegal characters within the encoded string<br>
* + The array CAN have illegal characters at the beginning and end, those
* will be dealt with appropriately.<br>
*
* @param sArr
* The source array. Length 0 will return an empty array.
* <code>null</code> will throw an exception.
* @return The decoded array of bytes. May be of length 0.
*/
public static byte[] decodeFast(final byte[] sArr) {
// Check special case
final int sLen = sArr.length;
if (sLen == 0) {
return new byte[0];
}
int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
// Trim illegal chars from start
while (sIx < eIx && IA[sArr[sIx] & 0xff] < 0) {
sIx++;
}
// Trim illegal chars from end
while (eIx > 0 && IA[sArr[eIx] & 0xff] < 0) {
eIx--;
}
// get the padding count (=) (0, 1 or 2)
final int pad = sArr[eIx] == '=' ? sArr[eIx - 1] == '=' ? 2 : 1 : 0; // Count '=' at end.
final int cCnt = eIx - sIx + 1; // Content count including possible separators
final int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
final int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
final byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
// Decode all but the last 0 - 2 bytes.
int d = 0;
for (int cc = 0, eLen = len / 3 * 3; d < eLen;) {
// Assemble three bytes into an int from four "valid" characters.
final int i =
IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6
| IA[sArr[sIx++]];
// Add the bytes
dArr[d++] = (byte) (i >> 16);
dArr[d++] = (byte) (i >> 8);
dArr[d++] = (byte) i;
// If line separator, jump over it.
if (sepCnt > 0 && ++cc == 19) {
sIx += 2;
cc = 0;
}
}
if (d < len) {
// Decode last 1-3 bytes (incl '=') into 1-3 bytes
int i = 0;
for (int j = 0; sIx <= eIx - pad; j++) {
i |= IA[sArr[sIx++]] << 18 - j * 6;
}
for (int r = 16; d < len; r -= 8) {
dArr[d++] = (byte) (i >> r);
}
}
return dArr;
}
/**
* Decodes a BASE64 encoded char array that is known to be resonably well
* formatted. The method is about twice as fast as {@link #decode(char[])}.
* The preconditions are:<br>
* + The array must have a line length of 76 chars OR no line separators at
* all (one line).<br>
* + Line separator must be "\r\n", as specified in RFC 2045 + The array
* must not contain illegal characters within the encoded string<br>
* + The array CAN have illegal characters at the beginning and end, those
* will be dealt with appropriately.<br>
*
* @param sArr
* The source array. Length 0 will return an empty array.
* <code>null</code> will throw an exception.
* @return The decoded array of bytes. May be of length 0.
*/
public static byte[] decodeFast(final char[] sArr) {
// Check special case
final int sLen = sArr.length;
if (sLen == 0) {
return new byte[0];
}
int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
// Trim illegal chars from start
while (sIx < eIx && IA[sArr[sIx]] < 0) {
sIx++;
}
// Trim illegal chars from end
while (eIx > 0 && IA[sArr[eIx]] < 0) {
eIx--;
}
// get the padding count (=) (0, 1 or 2)
final int pad = sArr[eIx] == '=' ? sArr[eIx - 1] == '=' ? 2 : 1 : 0; // Count '=' at end.
final int cCnt = eIx - sIx + 1; // Content count including possible separators
final int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
final int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
final byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
// Decode all but the last 0 - 2 bytes.
int d = 0;
for (int cc = 0, eLen = len / 3 * 3; d < eLen;) {
// Assemble three bytes into an int from four "valid" characters.
final int i =
IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6
| IA[sArr[sIx++]];
// Add the bytes
dArr[d++] = (byte) (i >> 16);
dArr[d++] = (byte) (i >> 8);
dArr[d++] = (byte) i;
// If line separator, jump over it.
if (sepCnt > 0 && ++cc == 19) {
sIx += 2;
cc = 0;
}
}
if (d < len) {
// Decode last 1-3 bytes (incl '=') into 1-3 bytes
int i = 0;
for (int j = 0; sIx <= eIx - pad; j++) {
i |= IA[sArr[sIx++]] << 18 - j * 6;
}
for (int r = 16; d < len; r -= 8) {
dArr[d++] = (byte) (i >> r);
}
}
return dArr;
}
/**
* Decodes a BASE64 encoded string that is known to be resonably well
* formatted. The method is about twice as fast as {@link #decode(String)}.
* The preconditions are:<br>
* + The array must have a line length of 76 chars OR no line separators at
* all (one line).<br>
* + Line separator must be "\r\n", as specified in RFC 2045 + The array
* must not contain illegal characters within the encoded string<br>
* + The array CAN have illegal characters at the beginning and end, those
* will be dealt with appropriately.<br>
*
* @param s
* The source string. Length 0 will return an empty array.
* <code>null</code> will throw an exception.
* @return The decoded array of bytes. May be of length 0.
*/
public static byte[] decodeFast(final String s) {
// Check special case
final int sLen = s.length();
if (sLen == 0) {
return new byte[0];
}
int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
// Trim illegal chars from start
while (sIx < eIx && IA[s.charAt(sIx) & 0xff] < 0) {
sIx++;
}
// Trim illegal chars from end
while (eIx > 0 && IA[s.charAt(eIx) & 0xff] < 0) {
eIx--;
}
// get the padding count (=) (0, 1 or 2)
final int pad = s.charAt(eIx) == '=' ? s.charAt(eIx - 1) == '=' ? 2 : 1 : 0; // Count '=' at end.
final int cCnt = eIx - sIx + 1; // Content count including possible separators
final int sepCnt = sLen > 76 ? (s.charAt(76) == '\r' ? cCnt / 78 : 0) << 1 : 0;
final int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
final byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
// Decode all but the last 0 - 2 bytes.
int d = 0;
for (int cc = 0, eLen = len / 3 * 3; d < eLen;) {
// Assemble three bytes into an int from four "valid" characters.
final int i =
IA[s.charAt(sIx++)] << 18 | IA[s.charAt(sIx++)] << 12
| IA[s.charAt(sIx++)] << 6 | IA[s.charAt(sIx++)];
// Add the bytes
dArr[d++] = (byte) (i >> 16);
dArr[d++] = (byte) (i >> 8);
dArr[d++] = (byte) i;
// If line separator, jump over it.
if (sepCnt > 0 && ++cc == 19) {
sIx += 2;
cc = 0;
}
}
if (d < len) {
// Decode last 1-3 bytes (incl '=') into 1-3 bytes
int i = 0;
for (int j = 0; sIx <= eIx - pad; j++) {
i |= IA[s.charAt(sIx++)] << 18 - j * 6;
}
for (int r = 16; d < len; r -= 8) {
dArr[d++] = (byte) (i >> r);
}
}
return dArr;
}
/**
* This method is using {@link #encode(byte[], boolean)}, and it only exists
* so we don't break the API.
*
* @param content
* The bytearray that needs to be Base64 encoded
* @return the Base64 encoded
*/
public static String encode(final byte[] content) {
return encode(content, false);
}
/**
* Encodes a raw byte array into a BASE64 <code>String</code> representation
* i accordance with RFC 2045.
*
* @param sArr
* The bytes to convert. If <code>null</code> or length 0 an
* empty array will be returned.
* @param lineSep
* Optional "\r\n" after 76 characters, unless end of file.<br>
* No line separator will be in breach of RFC 2045 which
* specifies max 76 per line but will be a little faster.
* @return A BASE64 encoded array. Never <code>null</code>.
*/
public static String encode(final byte[] sArr, final boolean lineSep) {
/*
* Reuse char[] since we can't create a String incrementally anyway and
* StringBuffer/Builder would be slower.
*/
return new String(encodeToChar(sArr, lineSep));
}
/**
* Encodes a raw byte array into a BASE64 <code>byte[]</code> representation
* i accordance with RFC 2045.
*
* @param sArr
* The bytes to convert. If <code>null</code> or length 0 an
* empty array will be returned.
* @param lineSep
* Optional "\r\n" after 76 characters, unless end of file.<br>
* No line separator will be in breach of RFC 2045 which
* specifies max 76 per line but will be a little faster.
* @return A BASE64 encoded array. Never <code>null</code>.
*/
public static byte[] encodeToByte(final byte[] sArr, final boolean lineSep) {
// Check special case
final int sLen = sArr != null ? sArr.length : 0;
if (sLen == 0) {
return new byte[0];
}
final int eLen = sLen / 3 * 3; // Length of even 24-bits.
final int cCnt = (sLen - 1) / 3 + 1 << 2; // Returned character count
final int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array
final byte[] dArr = new byte[dLen];
// Encode even 24-bits
for (int s = 0, d = 0, cc = 0; s < eLen;) {
// Copy next three bytes into lower 24 bits of int, paying attension to sign.
final int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | sArr[s++] & 0xff;
// Encode the int into four chars
dArr[d++] = (byte) CA[i >>> 18 & 0x3f];
dArr[d++] = (byte) CA[i >>> 12 & 0x3f];
dArr[d++] = (byte) CA[i >>> 6 & 0x3f];
dArr[d++] = (byte) CA[i & 0x3f];
// Add optional line separator
if (lineSep && ++cc == 19 && d < dLen - 2) {
dArr[d++] = '\r';
dArr[d++] = '\n';
cc = 0;
}
}
// Pad and encode last bits if source isn't an even 24 bits.
final int left = sLen - eLen; // 0 - 2.
if (left > 0) {
// Prepare the int
final int i =
(sArr[eLen] & 0xff) << 10 | (left == 2 ? (sArr[sLen - 1] & 0xff) << 2 : 0);
// Set last four chars
dArr[dLen - 4] = (byte) CA[i >> 12];
dArr[dLen - 3] = (byte) CA[i >>> 6 & 0x3f];
dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';
dArr[dLen - 1] = '=';
}
return dArr;
}
/**
* Encodes a raw byte array into a BASE64 <code>char[]</code> representation
* i accordance with RFC 2045.
*
* @param sArr
* The bytes to convert. If <code>null</code> or length 0 an
* empty array will be returned.
* @param lineSep
* Optional "\r\n" after 76 characters, unless end of file.<br>
* No line separator will be in breach of RFC 2045 which
* specifies max 76 per line but will be a little faster.
* @return A BASE64 encoded array. Never <code>null</code>.
*/
public static char[] encodeToChar(final byte[] sArr, final boolean lineSep) {
// Check special case
final int sLen = sArr != null ? sArr.length : 0;
if (sLen == 0) {
return new char[0];
}
final int eLen = sLen / 3 * 3; // Length of even 24-bits.
final int cCnt = (sLen - 1) / 3 + 1 << 2; // Returned character count
final int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array
final char[] dArr = new char[dLen];
// Encode even 24-bits
for (int s = 0, d = 0, cc = 0; s < eLen;) {
// Copy next three bytes into lower 24 bits of int, paying attension to sign.
final int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | sArr[s++] & 0xff;
// Encode the int into four chars
dArr[d++] = CA[i >>> 18 & 0x3f];
dArr[d++] = CA[i >>> 12 & 0x3f];
dArr[d++] = CA[i >>> 6 & 0x3f];
dArr[d++] = CA[i & 0x3f];
// Add optional line separator
if (lineSep && ++cc == 19 && d < dLen - 2) {
dArr[d++] = '\r';
dArr[d++] = '\n';
cc = 0;
}
}
// Pad and encode last bits if source isn't even 24 bits.
final int left = sLen - eLen; // 0 - 2.
if (left > 0) {
// Prepare the int
final int i =
(sArr[eLen] & 0xff) << 10 | (left == 2 ? (sArr[sLen - 1] & 0xff) << 2 : 0);
// Set last four chars
dArr[dLen - 4] = CA[i >> 12];
dArr[dLen - 3] = CA[i >>> 6 & 0x3f];
dArr[dLen - 2] = left == 2 ? CA[i & 0x3f] : '=';
dArr[dLen - 1] = '=';
}
return dArr;
}
private Base64() {
// No impl.
}
}