Base64.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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
*
* https://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 OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.codec.binary;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.Objects;
import org.apache.commons.codec.CodecPolicy;
/**
* Provides Base64 encoding and decoding as defined by <a href="https://www.ietf.org/rfc/rfc2045">RFC 2045 Multipurpose Internet Mail Extensions (MIME) Part
* One: Format of Internet Message Bodies</a> and portions of <a href="https://datatracker.ietf.org/doc/html/rfc4648">RFC 4648 The Base16, Base32, and Base64
* Data Encodings</a>
*
* <p>
* This class implements <a href="https://www.ietf.org/rfc/rfc2045#section-6.8">RFC 2045 6.8. Base64 Content-Transfer-Encoding</a>.
* </p>
* <p>
* The class can be parameterized in the following manner with various constructors:
* </p>
* <ul>
* <li>URL-safe mode: Default off.</li>
* <li>Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
* <li>Line separator: Default is CRLF ({@code "\r\n"})</li>
* </ul>
* <p>
* The URL-safe parameter is only applied to encode operations. Decoding seamlessly handles both modes.
* </p>
* <p>
* Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are
* compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
* </p>
* <p>
* This class is thread-safe.
* </p>
* <p>
* To configure a new instance, use a {@link Builder}. For example:
* </p>
*
* <pre>
* Base64 base64 = Base64.builder()
* .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient, null resets to default
* .setEncodeTable(customEncodeTable) // default is built in, null resets to default
* .setLineLength(0) // default is none
* .setLineSeparator('\r', '\n') // default is CR LF, null resets to default
* .setPadding('=') // default is '='
* .setUrlSafe(false) // default is false
* .get()
* </pre>
*
* @see Base64InputStream
* @see Base64OutputStream
* @see <a href="https://www.ietf.org/rfc/rfc2045">RFC 2045 Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</a>
* @see <a href="https://datatracker.ietf.org/doc/html/rfc4648">RFC 4648 The Base16, Base32, and Base64 Data Encodings</a>
* @since 1.0
*/
public class Base64 extends BaseNCodec {
/**
* Builds {@link Base64} instances.
*
* <p>
* To configure a new instance, use a {@link Builder}. For example:
* </p>
*
* <pre>
* Base64 base64 = Base64.builder()
* .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient, null resets to default
* .setEncodeTable(customEncodeTable) // default is built in, null resets to default
* .setLineLength(0) // default is none
* .setLineSeparator('\r', '\n') // default is CR LF, null resets to default
* .setPadding('=') // default is '='
* .setUrlSafe(false) // default is false
* .get()
* </pre>
*
* @since 1.17.0
*/
public static class Builder extends AbstractBuilder<Base64, Builder> {
/**
* Constructs a new instance.
*/
public Builder() {
super(STANDARD_ENCODE_TABLE);
setDecodeTableRaw(DECODE_TABLE);
setEncodeTableRaw(STANDARD_ENCODE_TABLE);
setEncodedBlockSize(BYTES_PER_ENCODED_BLOCK);
setUnencodedBlockSize(BYTES_PER_UNENCODED_BLOCK);
}
@Override
public Base64 get() {
return new Base64(this);
}
/**
* Sets the format of the decoding table. This method allows to explicitly state whether a standard or URL-safe Base64 decoding is expected. This method
* does not modify behavior on encoding operations. For configuration of the encoding behavior, please use {@link #setUrlSafe(boolean)} method.
* <p>
* By default, the implementation uses the {@link DecodeTableFormat#MIXED} approach, allowing a seamless handling of both
* {@link DecodeTableFormat#URL_SAFE} and {@link DecodeTableFormat#STANDARD} base64.
* </p>
*
* @param format table format to be used on Base64 decoding. Use {@link DecodeTableFormat#MIXED} or null to reset to the default behavior.
* @return {@code this} instance.
* @since 1.21
*/
public Builder setDecodeTableFormat(final DecodeTableFormat format) {
if (format == null) {
return setDecodeTableRaw(DECODE_TABLE);
}
switch (format) {
case STANDARD:
return setDecodeTableRaw(STANDARD_DECODE_TABLE);
case URL_SAFE:
return setDecodeTableRaw(URL_SAFE_DECODE_TABLE);
case MIXED:
default:
return setDecodeTableRaw(DECODE_TABLE);
}
}
@Override
public Builder setEncodeTable(final byte... encodeTable) {
final boolean isStandardEncodeTable = Arrays.equals(encodeTable, STANDARD_ENCODE_TABLE);
final boolean isUrlSafe = Arrays.equals(encodeTable, URL_SAFE_ENCODE_TABLE);
setDecodeTableRaw(isStandardEncodeTable || isUrlSafe ? DECODE_TABLE : calculateDecodeTable(encodeTable));
return super.setEncodeTable(encodeTable);
}
/**
* Sets the URL-safe encoding policy.
* <p>
* This method does not modify behavior on decoding operations. For configuration of the decoding behavior, please use
* {@code Builder.setDecodeTableFormat(DecodeTableFormat)} method.
* </p>
*
* @param urlSafe URL-safe encoding policy, null resets to the default.
* @return {@code this} instance.
*/
public Builder setUrlSafe(final boolean urlSafe) {
// Javadoc 8 can't find {@link #setDecodeTableFormat(DecodeTableFormat)}
return setEncodeTable(toUrlSafeEncodeTable(urlSafe));
}
}
/**
* Defines the Base64 table format to be used on decoding.
* <p>
* By default, the method uses {@link DecodeTableFormat#MIXED} approach, allowing a seamless handling of both {@link DecodeTableFormat#URL_SAFE} and
* {@link DecodeTableFormat#STANDARD} base64 options.
* </p>
*
* @since 1.21
*/
public enum DecodeTableFormat {
/**
* Corresponds to the standard Base64 coding table, as specified in
* <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The Base64 Alphabet</a>.
*/
STANDARD,
/**
* Corresponds to the URL-safe Base64 coding table, as specified in
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC
* 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet</a>.
*/
URL_SAFE,
/**
* Represents a joint approach, allowing a seamless decoding of both character sets, corresponding to either
* <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The Base64 Alphabet</a> or
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC
* 4648 Table 2: The "URL and Filename safe" Base 64 Alphabet</a>. This decoding table is used by default.
*/
MIXED
}
/**
* BASE64 characters are 6 bits in length.
* They are formed by taking a block of 3 octets to form a 24-bit string,
* which is converted into 4 BASE64 characters.
*/
private static final int BITS_PER_ENCODED_BYTE = 6;
private static final int BYTES_PER_UNENCODED_BLOCK = 3;
private static final int BYTES_PER_ENCODED_BLOCK = 4;
private static final int DECODING_TABLE_LENGTH = 256;
/**
* This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet" equivalents as specified in
* <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The Base64 Alphabet</a>.
* <p>
* Thanks to "commons" project in ws.apache.org for this code. https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
* </p>
*/
// @formatter:off
private static final byte[] STANDARD_ENCODE_TABLE = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};
/**
* This is a copy of the STANDARD_ENCODE_TABLE above, but with + and / changed to - and _ to make the encoded Base64 results more URL-SAFE. This table is
* only used when the Base64's mode is set to URL-SAFE.
*/
// @formatter:off
private static final byte[] URL_SAFE_ENCODE_TABLE = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
};
// @formatter:on
/**
* This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
* <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The Base64 Alphabet</a>) into their 6-bit
* positive integer equivalents. Characters that are not in the Base64 or Base64 URL-safe alphabets but fall within the bounds of the array are translated
* to -1.
* <p>
* The characters '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both URL_SAFE and STANDARD base64.
* (The encoder, on the other hand, needs to know ahead of time what to emit).
* </p>
* <p>
* Thanks to "commons" project in ws.apache.org for this code. https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
* </p>
*/
private static final byte[] DECODE_TABLE = {
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, // 20-2f + - /
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, // 30-3f 0-9
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 40-4f A-O
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, // 50-5f P-Z _
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 60-6f a-o
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 // 70-7a p-z
};
/**
* This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
* <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The Base64 Alphabet</a>) into their 6-bit
* positive integer equivalents. Characters that are not in the Base64 alphabet but fall within the bounds of the array are translated to -1. This decoding
* table handles only the standard base64 characters, such as '+' and '/'. The "url-safe" characters such as '-' and '_' are not supported by the table.
*/
private static final byte[] STANDARD_DECODE_TABLE = {
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, // 20-2f + /
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, // 30-3f 0-9
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 40-4f A-O
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, // 50-5f P-Z
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 60-6f a-o
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 // 70-7a p-z
};
/**
* This array is a lookup table that translates Unicode characters drawn from the "Base64 URL-safe Alphabet" (as specified in
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC 4648
* Table 2: The "URL and Filename safe" Base 64 Alphabet</a>) into their 6-bit positive integer equivalents. Characters that are not in the Base64 URL-safe
* alphabet but fall within the bounds of the array are translated to -1. This decoding table handles only the URL-safe base64 characters, such as '-' and
* '_'. The standard characters such as '+' and '/' are not supported by the table.
*/
private static final byte[] URL_SAFE_DECODE_TABLE = {
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, // 20-2f -
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, // 30-3f 0-9
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 40-4f A-O
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, // 50-5f P-Z _
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 60-6f a-o
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 // 70-7a p-z
};
/**
* Base64 uses 6-bit fields.
*/
/** Mask used to extract 6 bits, used when encoding */
private static final int MASK_6_BITS = 0x3f;
// The static final fields above are used for the original static byte[] methods on Base64.
// The private member fields below are used with the new streaming approach, which requires
// some state be preserved between calls of encode() and decode().
/** Mask used to extract 4 bits, used when decoding final trailing character. */
private static final int MASK_4_BITS = 0xf;
/** Mask used to extract 2 bits, used when decoding final trailing character. */
private static final int MASK_2_BITS = 0x3;
/**
* Creates a new Builder.
*
* <p>
* To configure a new instance, use a {@link Builder}. For example:
* </p>
*
* <pre>
* Base64 base64 = Base64.builder()
* .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient, null resets to default
* .setEncodeTable(customEncodeTable) // default is built in, null resets to default
* .setLineLength(0) // default is none
* .setLineSeparator('\r', '\n') // default is CR LF, null resets to default
* .setPadding('=') // default is '='
* .setUrlSafe(false) // default is false
* .get()
* </pre>
*
* @return a new Builder.
* @since 1.17.0
*/
public static Builder builder() {
return new Builder();
}
/**
* Calculates a decode table for a given encode table.
*
* @param encodeTable that is used to determine decode lookup table.
* @return A new decode table.
*/
private static byte[] calculateDecodeTable(final byte[] encodeTable) {
final byte[] decodeTable = new byte[DECODING_TABLE_LENGTH];
Arrays.fill(decodeTable, (byte) -1);
for (int i = 0; i < encodeTable.length; i++) {
decodeTable[encodeTable[i]] = (byte) i;
}
return decodeTable;
}
/**
* Decodes Base64 data into octets.
* <p>
* This method seamlessly handles data encoded in URL-safe or normal mode. For enforcing verification against strict standard Base64 or Base64 URL-safe
* tables, please use {@link #decodeBase64Standard(byte[])} or {@link #decodeBase64UrlSafe(byte[])} methods respectively. This method skips any unknown or
* not supported bytes.
* </p>
*
* @param base64Data Byte array containing Base64 data.
* @return New array containing decoded data.
*/
public static byte[] decodeBase64(final byte[] base64Data) {
return new Base64().decode(base64Data);
}
/**
* Decodes a Base64 String into octets.
* <p>
* This method seamlessly handles data encoded in URL-safe or normal mode. For enforcing verification against strict standard Base64 or Base64 URL-safe
* tables, please use {@link #decodeBase64Standard(String)} or {@link #decodeBase64UrlSafe(String)} methods respectively. This method skips any unknown or
* not supported bytes.
* </p>
*
* @param base64String String containing Base64 data.
* @return New array containing decoded data.
* @since 1.4
*/
public static byte[] decodeBase64(final String base64String) {
return new Base64().decode(base64String);
}
/**
* Decodes standard Base64 data into octets.
* <p>
* This implementation is aligned with the <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The
* Base64 Alphabet</a>. This method skips any unknown or not supported bytes.
* </p>
*
* @param base64Data Byte array containing Base64 data.
* @return New array containing decoded data.
* @since 1.21
*/
public static byte[] decodeBase64Standard(final byte[] base64Data) {
return builder().setDecodeTableFormat(DecodeTableFormat.STANDARD).get().decode(base64Data);
}
/**
* Decodes a standard Base64 String into octets.
* <p>
* This implementation is aligned with the <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The
* Base64 Alphabet</a>. This method skips any unknown or not supported characters.
* </p>
*
* @param base64String String containing Base64 data.
* @return New array containing decoded data.
* @since 1.21
*/
public static byte[] decodeBase64Standard(final String base64String) {
return builder().setDecodeTableFormat(DecodeTableFormat.STANDARD).get().decode(base64String);
}
/**
* Decodes URL-safe Base64 data into octets.
* <p>
* This implementation is aligned with
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC 4648
* Table 2: The "URL and Filename safe" Base 64 Alphabet</a>. This method skips any unknown or not supported characters.
* </p>
*
* @param base64Data Byte array containing Base64 data.
* @return New array containing decoded data.
* @since 1.21
*/
public static byte[] decodeBase64UrlSafe(final byte[] base64Data) {
return builder().setDecodeTableFormat(DecodeTableFormat.URL_SAFE).get().decode(base64Data);
}
/**
* Decodes a URL-safe Base64 String into octets.
* <p>
* This implementation is aligned with
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC 4648
* Table 2: The "URL and Filename safe" Base 64 Alphabet</a>. This method skips any unknown or not supported characters.
* </p>
*
* @param base64String String containing Base64 data.
* @return New array containing decoded data.
* @since 1.21
*/
public static byte[] decodeBase64UrlSafe(final String base64String) {
return builder().setDecodeTableFormat(DecodeTableFormat.URL_SAFE).get().decode(base64String);
}
/**
* Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
*
* @param array a byte array containing base64 character data.
* @return A BigInteger.
* @since 1.4
*/
public static BigInteger decodeInteger(final byte[] array) {
return new BigInteger(1, decodeBase64(array));
}
/**
* Encodes binary data using the base64 algorithm but does not chunk the output.
*
* @param binaryData binary data to encode.
* @return byte[] containing Base64 characters in their UTF-8 representation.
*/
public static byte[] encodeBase64(final byte[] binaryData) {
return encodeBase64(binaryData, false);
}
/**
* Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if {@code true} this encoder will chunk the base64 output into 76 character blocks.
* @return Base64-encoded data.
* @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}.
*/
public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked) {
return encodeBase64(binaryData, isChunked, false);
}
/**
* Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if {@code true} this encoder will chunk the base64 output into 76 character blocks.
* @param urlSafe if {@code true} this encoder will emit - and _ instead of the usual + and / characters. <strong>No padding is added when encoding using
* the URL-safe alphabet.</strong>
* @return Base64-encoded data.
* @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}.
* @since 1.4
*/
public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe) {
return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
}
/**
* Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if {@code true} this encoder will chunk the base64 output into 76 character blocks.
* @param urlSafe if {@code true} this encoder will emit - and _ instead of the usual + and / characters. <strong>No padding is added when encoding
* using the URL-safe alphabet.</strong>
* @param maxResultSize The maximum result size to accept.
* @return Base64-encoded data.
* @throws IllegalArgumentException Thrown when the input array needs an output array bigger than maxResultSize.
* @since 1.4
*/
public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe, final int maxResultSize) {
if (BinaryCodec.isEmpty(binaryData)) {
return binaryData;
}
// Create this so can use the super-class method
// Also ensures that the same roundings are performed by the ctor and the code
final Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
final long len = b64.getEncodedLength(binaryData);
if (len > maxResultSize) {
throw new IllegalArgumentException(
"Input array too big, the output array would be bigger (" + len + ") than the specified maximum size of " + maxResultSize);
}
return b64.encode(binaryData);
}
/**
* Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
*
* @param binaryData binary data to encode.
* @return Base64 characters chunked in 76 character blocks.
*/
public static byte[] encodeBase64Chunked(final byte[] binaryData) {
return encodeBase64(binaryData, true);
}
/**
* Encodes binary data using the base64 algorithm but does not chunk the output.
* <p>
* <strong> We changed the behavior of this method from multi-line chunking (1.4) to single-line non-chunking (1.5).</strong>
* </p>
*
* @param binaryData binary data to encode.
* @return String containing Base64 characters.
* @since 1.4 (NOTE: 1.4 chunked the output, whereas 1.5 does not).
*/
public static String encodeBase64String(final byte[] binaryData) {
return StringUtils.newStringUsAscii(encodeBase64(binaryData, false));
}
/**
* Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The url-safe variation emits - and _ instead of +
* and / characters. <strong>No padding is added.</strong>
*
* @param binaryData binary data to encode.
* @return byte[] containing Base64 characters in their UTF-8 representation.
* @since 1.4
*/
public static byte[] encodeBase64URLSafe(final byte[] binaryData) {
return encodeBase64(binaryData, false, true);
}
/**
* Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The url-safe variation emits - and _ instead of +
* and / characters. <strong>No padding is added.</strong>
*
* @param binaryData binary data to encode.
* @return String containing Base64 characters.
* @since 1.4
*/
public static String encodeBase64URLSafeString(final byte[] binaryData) {
return StringUtils.newStringUsAscii(encodeBase64(binaryData, false, true));
}
/**
* Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
*
* @param bigInteger a BigInteger.
* @return A byte array containing base64 character data.
* @throws NullPointerException if null is passed in.
* @since 1.4
*/
public static byte[] encodeInteger(final BigInteger bigInteger) {
Objects.requireNonNull(bigInteger, "bigInteger");
return encodeBase64(toIntegerBytes(bigInteger), false);
}
/**
* Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the method treats whitespace as valid.
*
* @param arrayOctet byte array to test.
* @return {@code true} if all bytes are valid characters in the Base64 alphabet or if the byte array is empty; {@code false}, otherwise.
* @deprecated 1.5 Use {@link #isBase64(byte[])}, will be removed in 2.0.
*/
@Deprecated
public static boolean isArrayByteBase64(final byte[] arrayOctet) {
return isBase64(arrayOctet);
}
/**
* Tests whether or not the {@code octet} is in the base 64 alphabet.
* <p>
* This method threats all characters included within standard base64 and base64url encodings as valid base64 characters. This includes the '+' and '/'
* (standard base64), as well as '-' and '_' (URL-safe base64) characters. For enforcing verification against strict standard Base64 or Base64 URL-safe
* tables, please use {@link #isBase64Standard(byte)} or {@link #isBase64Url(byte)} methods respectively.
* </p>
*
* @param octet The value to test.
* @return {@code true} if the value is defined in the base 64 alphabet, {@code false} otherwise.
* @since 1.4
*/
public static boolean isBase64(final byte octet) {
return octet == PAD_DEFAULT || octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1;
}
/**
* Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the method treats whitespace as valid.
* <p>
* This method treats all characters included within standard base64 and base64url encodings as valid base64 characters. This includes the '+' and '/'
* (standard base64), as well as '-' and '_' (URL-safe base64) characters. For enforcing verification against strict standard Base64 or Base64 URL-safe
* tables, please use {@link #isBase64Standard(byte[])} or {@link #isBase64Url(byte[])} methods respectively.
* </p>
*
* @param arrayOctet byte array to test.
* @return {@code true} if all bytes are valid characters in the Base64 alphabet or if the byte array is empty; {@code false}, otherwise.
* @since 1.5
*/
public static boolean isBase64(final byte[] arrayOctet) {
for (final byte element : arrayOctet) {
if (!isBase64(element) && !Character.isWhitespace(element)) {
return false;
}
}
return true;
}
/**
* Tests a given String to see if it contains only valid characters within the Base64 alphabet. Currently the method treats whitespace as valid.
* <p>
* This method threats all characters included within standard base64 and base64url encodings as valid base64 characters. This includes the '+' and '/'
* (standard base64), as well as '-' and '_' (URL-safe base64) characters. For enforcing verification against strict standard Base64 or Base64 URL-safe
* tables, please use {@link #isBase64Standard(String)} or {@link #isBase64Url(String)} methods respectively.
* </p>
*
* @param base64 String to test.
* @return {@code true} if all characters in the String are valid characters in the Base64 alphabet or if the String is empty; {@code false}, otherwise.
* @since 1.5
*/
public static boolean isBase64(final String base64) {
return isBase64(StringUtils.getBytesUtf8(base64));
}
/**
* Tests whether or not the {@code octet} is in the standard base 64 alphabet.
* <p>
* This implementation is aligned with <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The
* Base64 Alphabet</a>.
* </p>
*
* @param octet The value to test.
* @return {@code true} if the value is defined in the standard base 64 alphabet, {@code false} otherwise.
* @since 1.21
*/
public static boolean isBase64Standard(final byte octet) {
return octet == PAD_DEFAULT || octet >= 0 && octet < STANDARD_DECODE_TABLE.length && STANDARD_DECODE_TABLE[octet] != -1;
}
/**
* Tests a given byte array to see if it contains only valid characters within the standard Base64 alphabet. The method treats whitespace as valid.
* <p>
* This implementation is aligned with <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The
* Base64 Alphabet</a>.
* </p>
*
* @param arrayOctet byte array to test.
* @return {@code true} if all bytes are valid characters in the standard Base64 alphabet. {@code false}, otherwise.
* @since 1.21
*/
public static boolean isBase64Standard(final byte[] arrayOctet) {
for (final byte element : arrayOctet) {
if (!isBase64Standard(element) && !Character.isWhitespace(element)) {
return false;
}
}
return true;
}
/**
* Tests a given String to see if it contains only valid characters within the standard Base64 alphabet. The method treats whitespace as valid.
* <p>
* This implementation is aligned with <a href="https://www.ietf.org/rfc/rfc2045#:~:text=Table%201%3A%20The%20Base64%20Alphabet">RFC 2045 Table 1: The
* Base64 Alphabet</a>.
* </p>
*
* @param base64 String to test.
* @return {@code true} if all characters in the String are valid characters in the standard Base64 alphabet or if the String is empty; {@code false},
* otherwise.
* @since 1.21
*/
public static boolean isBase64Standard(final String base64) {
return isBase64Standard(StringUtils.getBytesUtf8(base64));
}
/**
* Tests whether or not the {@code octet} is in the URL-safe base 64 alphabet.
* <p>
* This implementation is aligned with
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC 4648
* Table 2: The "URL and Filename safe" Base 64 Alphabet</a>.
* </p>
*
* @param octet The value to test.
* @return {@code true} if the value is defined in the URL-safe base 64 alphabet, {@code false} otherwise.
* @since 1.21
*/
public static boolean isBase64Url(final byte octet) {
return octet == PAD_DEFAULT || octet >= 0 && octet < URL_SAFE_DECODE_TABLE.length && URL_SAFE_DECODE_TABLE[octet] != -1;
}
/**
* Tests a given byte array to see if it contains only valid characters within the URL-safe Base64 alphabet. The method treats whitespace as valid.
* <p>
* This implementation is aligned with
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC 4648
* Table 2: The "URL and Filename safe" Base 64 Alphabet</a>.
* </p>
*
* @param arrayOctet byte array to test.
* @return {@code true} if all bytes are valid characters in the URL-safe Base64 alphabet, {@code false}, otherwise.
* @since 1.21
*/
public static boolean isBase64Url(final byte[] arrayOctet) {
for (final byte element : arrayOctet) {
if (!isBase64Url(element) && !Character.isWhitespace(element)) {
return false;
}
}
return true;
}
/**
* Tests a given String to see if it contains only valid characters within the URL-safe Base64 alphabet. The method treats whitespace as valid.
* <p>
* This implementation is aligned with
* <a href="https://datatracker.ietf.org/doc/html/rfc4648#:~:text=Table%202%3A%20The%20%22URL%20and%20Filename%20safe%22%20Base%2064%20Alphabet">RFC 4648
* Table 2: The "URL and Filename safe" Base 64 Alphabet</a>.
* </p>
*
* @param base64 String to test.
* @return {@code true} if all characters in the String are valid characters in the URL-safe Base64 alphabet or if the String is empty; {@code false},
* otherwise.
* @since 1.21
*/
public static boolean isBase64Url(final String base64) {
return isBase64Url(StringUtils.getBytesUtf8(base64));
}
/**
* Returns a byte-array representation of a {@code BigInteger} without sign bit.
*
* @param bigInt {@code BigInteger} to be converted.
* @return a byte array representation of the BigInteger parameter.
*/
static byte[] toIntegerBytes(final BigInteger bigInt) {
int bitlen = bigInt.bitLength();
// round bitlen
bitlen = bitlen + 7 >> 3 << 3;
final byte[] bigBytes = bigInt.toByteArray();
if (bigInt.bitLength() % 8 != 0 && bigInt.bitLength() / 8 + 1 == bitlen / 8) {
return bigBytes;
}
// set up params for copying everything but sign bit
int startSrc = 0;
int len = bigBytes.length;
// if bigInt is exactly byte-aligned, just skip signbit in copy
if (bigInt.bitLength() % 8 == 0) {
startSrc = 1;
len--;
}
final int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
final byte[] resizedBytes = new byte[bitlen / 8];
System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
return resizedBytes;
}
static byte[] toUrlSafeEncodeTable(final boolean urlSafe) {
return urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
}
/**
* Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
*/
private final byte[] lineSeparator;
/**
* Convenience variable to help us determine when our buffer is going to run out of room and needs resizing. {@code encodeSize = 4 + lineSeparator.length;}
*/
private final int encodeSize;
private final boolean isUrlSafe;
private final boolean isStandardEncodeTable;
/**
* Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
* <p>
* When encoding the line length is 0 (no chunking), and the encoding table is STANDARD_ENCODE_TABLE.
* </p>
* <p>
* When decoding all variants are supported.
* </p>
*/
public Base64() {
this(0);
}
/**
* Constructs a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
* <p>
* When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
* </p>
* <p>
* When decoding all variants are supported.
* </p>
*
* @param urlSafe if {@code true}, URL-safe encoding is used. In most cases this should be set to {@code false}.
* @since 1.4
* @deprecated Use {@link #builder()} and {@link Builder}.
*/
@Deprecated
public Base64(final boolean urlSafe) {
this(MIME_CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
}
private Base64(final Builder builder) {
super(builder);
final byte[] encTable = builder.getEncodeTable();
if (encTable.length != STANDARD_ENCODE_TABLE.length) {
throw new IllegalArgumentException("encodeTable must have exactly 64 entries.");
}
this.isStandardEncodeTable = Arrays.equals(encTable, STANDARD_ENCODE_TABLE);
this.isUrlSafe = Arrays.equals(encTable, URL_SAFE_ENCODE_TABLE);
// TODO could be simplified if there is no requirement to reject invalid line sep when length <=0
// @see test case Base64Test.testConstructors()
if (builder.getLineSeparator().length > 0) {
final byte[] lineSeparatorB = builder.getLineSeparator();
if (containsAlphabetOrPad(lineSeparatorB)) {
final String sep = StringUtils.newStringUtf8(lineSeparatorB);
throw new IllegalArgumentException("lineSeparator must not contain base64 characters: [" + sep + "]");
}
if (builder.getLineLength() > 0) { // null line-sep forces no chunking rather than throwing IAE
this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparatorB.length;
this.lineSeparator = lineSeparatorB;
} else {
this.encodeSize = BYTES_PER_ENCODED_BLOCK;
this.lineSeparator = null;
}
} else {
this.encodeSize = BYTES_PER_ENCODED_BLOCK;
this.lineSeparator = null;
}
}
/**
* Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
* <p>
* When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
* </p>
* <p>
* Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
* </p>
* <p>
* When decoding all variants are supported.
* </p>
*
* @param lineLength Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0, then
* the output will not be divided into lines (chunks). Ignored when decoding.
* @since 1.4
* @deprecated Use {@link #builder()} and {@link Builder}.
*/
@Deprecated
public Base64(final int lineLength) {
this(lineLength, CHUNK_SEPARATOR);
}
/**
* Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
* <p>
* When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
* </p>
* <p>
* Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
* </p>
* <p>
* When decoding all variants are supported.
* </p>
*
* @param lineLength Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0,
* then the output will not be divided into lines (chunks). Ignored when decoding.
* @param lineSeparator Each line of encoded data will end with this sequence of bytes.
* @throws IllegalArgumentException Thrown when the provided lineSeparator included some base64 characters.
* @since 1.4
* @deprecated Use {@link #builder()} and {@link Builder}.
*/
@Deprecated
public Base64(final int lineLength, final byte[] lineSeparator) {
this(lineLength, lineSeparator, false);
}
/**
* Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
* <p>
* When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
* </p>
* <p>
* Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
* </p>
* <p>
* When decoding all variants are supported.
* </p>
*
* @param lineLength Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0,
* then the output will not be divided into lines (chunks). Ignored when decoding.
* @param lineSeparator Each line of encoded data will end with this sequence of bytes.
* @param urlSafe Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode operations. Decoding seamlessly
* handles both modes. <strong>No padding is added when using the URL-safe alphabet.</strong>
* @throws IllegalArgumentException Thrown when the {@code lineSeparator} contains Base64 characters.
* @since 1.4
* @deprecated Use {@link #builder()} and {@link Builder}.
*/
@Deprecated
public Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe) {
this(builder().setLineLength(lineLength).setLineSeparator(lineSeparator != null ? lineSeparator : EMPTY_BYTE_ARRAY).setPadding(PAD_DEFAULT)
.setEncodeTableRaw(toUrlSafeEncodeTable(urlSafe)).setDecodingPolicy(DECODING_POLICY_DEFAULT));
}
/**
* Constructs a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
* <p>
* When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
* </p>
* <p>
* Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
* </p>
* <p>
* When decoding all variants are supported.
* </p>
*
* @param lineLength Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4). If lineLength <= 0,
* then the output will not be divided into lines (chunks). Ignored when decoding.
* @param lineSeparator Each line of encoded data will end with this sequence of bytes.
* @param urlSafe Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode operations. Decoding seamlessly
* handles both modes. <strong>No padding is added when using the URL-safe alphabet.</strong>
* @param decodingPolicy The decoding policy.
* @throws IllegalArgumentException Thrown when the {@code lineSeparator} contains Base64 characters.
* @since 1.15
* @deprecated Use {@link #builder()} and {@link Builder}.
*/
@Deprecated
public Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe, final CodecPolicy decodingPolicy) {
this(builder().setLineLength(lineLength).setLineSeparator(lineSeparator).setPadding(PAD_DEFAULT).setEncodeTableRaw(toUrlSafeEncodeTable(urlSafe))
.setDecodingPolicy(decodingPolicy));
}
/**
* <p>
* Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once with the data to decode, and once with
* inAvail set to "-1" to alert decoder that EOF has been reached. The "-1" call is not necessary when decoding, but it doesn't hurt, either.
* </p>
* <p>
* Ignores all non-base64 characters. This is how chunked (for example 76 character) data is handled, since CR and LF are silently ignored, but has
* implications for other bytes, too. This method subscribes to the garbage-in, garbage-out philosophy: it will not check the provided data for validity.
* </p>
* <p>
* Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
* https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
* </p>
*
* @param input byte[] array of ASCII data to base64 decode.
* @param inPos Position to start reading data from.
* @param inAvail Amount of bytes available from input for decoding.
* @param context the context to be used.
*/
@Override
void decode(final byte[] input, int inPos, final int inAvail, final Context context) {
if (context.eof) {
return;
}
if (inAvail < 0) {
context.eof = true;
}
final int decodeSize = this.encodeSize - 1;
for (int i = 0; i < inAvail; i++) {
final byte[] buffer = ensureBufferSize(decodeSize, context);
final byte b = input[inPos++];
if (b == pad) {
// We're done.
context.eof = true;
break;
}
if (b >= 0 && b < decodeTable.length) {
final int result = decodeTable[b];
if (result >= 0) {
context.modulus = (context.modulus + 1) % BYTES_PER_ENCODED_BLOCK;
context.ibitWorkArea = (context.ibitWorkArea << BITS_PER_ENCODED_BYTE) + result;
if (context.modulus == 0) {
buffer[context.pos++] = (byte) (context.ibitWorkArea >> 16 & MASK_8BITS);
buffer[context.pos++] = (byte) (context.ibitWorkArea >> 8 & MASK_8BITS);
buffer[context.pos++] = (byte) (context.ibitWorkArea & MASK_8BITS);
}
}
}
}
// Two forms of EOF as far as base64 decoder is concerned: actual
// EOF (-1) and first time '=' character is encountered in stream.
// This approach makes the '=' padding characters completely optional.
if (context.eof && context.modulus != 0) {
final byte[] buffer = ensureBufferSize(decodeSize, context);
// We have some spare bits remaining
// Output all whole multiples of 8 bits and ignore the rest
switch (context.modulus) {
// case 0 : // impossible, as excluded above
case 1 : // 6 bits - either ignore entirely, or raise an exception
validateTrailingCharacter();
break;
case 2 : // 12 bits = 8 + 4
validateCharacter(MASK_4_BITS, context);
context.ibitWorkArea = context.ibitWorkArea >> 4; // dump the extra 4 bits
buffer[context.pos++] = (byte) (context.ibitWorkArea & MASK_8BITS);
break;
case 3 : // 18 bits = 8 + 8 + 2
validateCharacter(MASK_2_BITS, context);
context.ibitWorkArea = context.ibitWorkArea >> 2; // dump 2 bits
buffer[context.pos++] = (byte) (context.ibitWorkArea >> 8 & MASK_8BITS);
buffer[context.pos++] = (byte) (context.ibitWorkArea & MASK_8BITS);
break;
default:
throw new IllegalStateException("Impossible modulus " + context.modulus);
}
}
}
/**
* <p>
* Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with the data to encode, and once with
* inAvail set to "-1" to alert encoder that EOF has been reached, to flush last remaining bytes (if not multiple of 3).
* </p>
* <p>
* <strong>No padding is added when encoding using the URL-safe alphabet.</strong>
* </p>
* <p>
* Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
* https://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
* </p>
*
* @param in byte[] array of binary data to base64 encode.
* @param inPos Position to start reading data from.
* @param inAvail Amount of bytes available from input for encoding.
* @param context the context to be used.
*/
@Override
void encode(final byte[] in, int inPos, final int inAvail, final Context context) {
if (context.eof) {
return;
}
// inAvail < 0 is how we're informed of EOF in the underlying data we're
// encoding.
if (inAvail < 0) {
context.eof = true;
if (0 == context.modulus && lineLength == 0) {
return; // no leftovers to process and not using chunking
}
final byte[] buffer = ensureBufferSize(encodeSize, context);
final int savedPos = context.pos;
switch (context.modulus) { // 0-2
case 0 : // nothing to do here
break;
case 1 : // 8 bits = 6 + 2
// top 6 bits:
buffer[context.pos++] = encodeTable[context.ibitWorkArea >> 2 & MASK_6_BITS];
// remaining 2:
buffer[context.pos++] = encodeTable[context.ibitWorkArea << 4 & MASK_6_BITS];
// URL-SAFE skips the padding to further reduce size.
if (isStandardEncodeTable) {
buffer[context.pos++] = pad;
buffer[context.pos++] = pad;
}
break;
case 2 : // 16 bits = 6 + 6 + 4
buffer[context.pos++] = encodeTable[context.ibitWorkArea >> 10 & MASK_6_BITS];
buffer[context.pos++] = encodeTable[context.ibitWorkArea >> 4 & MASK_6_BITS];
buffer[context.pos++] = encodeTable[context.ibitWorkArea << 2 & MASK_6_BITS];
// URL-SAFE skips the padding to further reduce size.
if (isStandardEncodeTable) {
buffer[context.pos++] = pad;
}
break;
default:
throw new IllegalStateException("Impossible modulus " + context.modulus);
}
context.currentLinePos += context.pos - savedPos; // keep track of current line position
// if currentPos == 0 we are at the start of a line, so don't add CRLF
if (lineLength > 0 && context.currentLinePos > 0) {
System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
context.pos += lineSeparator.length;
}
} else {
for (int i = 0; i < inAvail; i++) {
final byte[] buffer = ensureBufferSize(encodeSize, context);
context.modulus = (context.modulus + 1) % BYTES_PER_UNENCODED_BLOCK;
int b = in[inPos++];
if (b < 0) {
b += 256;
}
context.ibitWorkArea = (context.ibitWorkArea << 8) + b; // BITS_PER_BYTE
if (0 == context.modulus) { // 3 bytes = 24 bits = 4 * 6 bits to extract
buffer[context.pos++] = encodeTable[context.ibitWorkArea >> 18 & MASK_6_BITS];
buffer[context.pos++] = encodeTable[context.ibitWorkArea >> 12 & MASK_6_BITS];
buffer[context.pos++] = encodeTable[context.ibitWorkArea >> 6 & MASK_6_BITS];
buffer[context.pos++] = encodeTable[context.ibitWorkArea & MASK_6_BITS];
context.currentLinePos += BYTES_PER_ENCODED_BLOCK;
if (lineLength > 0 && lineLength <= context.currentLinePos) {
System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
context.pos += lineSeparator.length;
context.currentLinePos = 0;
}
}
}
}
}
/**
* Gets the line separator (for testing only).
*
* @return the line separator.
*/
byte[] getLineSeparator() {
return lineSeparator;
}
/**
* Returns whether or not the {@code octet} is in the Base64 alphabet.
*
* @param octet The value to test.
* @return {@code true} if the value is defined in the Base64 alphabet {@code false} otherwise.
*/
@Override
protected boolean isInAlphabet(final byte octet) {
return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
}
/**
* Returns our current encode mode. True if we're URL-safe, false otherwise.
*
* @return true if we're in URL-safe mode, false otherwise.
* @since 1.4
*/
public boolean isUrlSafe() {
return isUrlSafe;
}
/**
* Validates whether decoding the final trailing character is possible in the context of the set of possible base 64 values.
* <p>
* The character is valid if the lower bits within the provided mask are zero. This is used to test the final trailing base-64 digit is zero in the bits
* that will be discarded.
* </p>
*
* @param emptyBitsMask The mask of the lower bits that should be empty.
* @param context the context to be used.
* @throws IllegalArgumentException if the bits being checked contain any non-zero value.
*/
private void validateCharacter(final int emptyBitsMask, final Context context) {
if (isStrictDecoding() && (context.ibitWorkArea & emptyBitsMask) != 0) {
throw new IllegalArgumentException(
"Strict decoding: Last encoded character (before the paddings if any) is a valid " +
"base 64 alphabet but not a possible encoding. " +
"Expected the discarded bits from the character to be zero.");
}
}
/**
* Validates whether decoding allows an entire final trailing character that cannot be used for a complete byte.
*
* @throws IllegalArgumentException if strict decoding is enabled.
*/
private void validateTrailingCharacter() {
if (isStrictDecoding()) {
throw new IllegalArgumentException(
"Strict decoding: Last encoded character (before the paddings if any) is a valid " +
"base 64 alphabet but not a possible encoding. " +
"Decoding requires at least two trailing 6-bit characters to create bytes.");
}
}
}