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com.microsoft.azure.storage.core.Base64 Maven / Gradle / Ivy
/**
* Copyright Microsoft Corporation
*
* 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 OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.microsoft.azure.storage.core;
/**
* RESERVED FOR INTERNAL USE. Provides Base64 encoding, decoding, and validation functionality.
*/
public final class Base64 {
/**
* The Base 64 Characters.
*/
private static final String BASE_64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/**
* Decoded values, -1 is invalid character, -2 is = pad character.
*/
private static final byte DECODE_64[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0-15
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*
* 16- 31
*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /*
* 32- 47
*/
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, /*
* 48- 63
*/
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 64-79 */
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /*
* 80- 95
*/
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /*
* 96- 111
*/
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 /*
* 112- 127
*/
};
/**
* Decodes a given Base64 string into its corresponding byte array.
*
* @param data
* the Base64 string, as a String object, to decode
*
* @return the corresponding decoded byte array
* @throws IllegalArgumentException
* If the string is not a valid base64 encoded string
*/
public static byte[] decode(final String data) {
if (data == null) {
throw new IllegalArgumentException(SR.STRING_NOT_VALID);
}
int byteArrayLength = 3 * data.length() / 4;
if (data.endsWith("==")) {
byteArrayLength -= 2;
}
else if (data.endsWith("=")) {
byteArrayLength -= 1;
}
final byte[] retArray = new byte[byteArrayLength];
int byteDex = 0;
int charDex = 0;
for (; charDex < data.length(); charDex += 4) {
// get 4 chars, convert to 3 bytes
final int char1 = DECODE_64[(byte) data.charAt(charDex)];
final int char2 = DECODE_64[(byte) data.charAt(charDex + 1)];
final int char3 = DECODE_64[(byte) data.charAt(charDex + 2)];
final int char4 = DECODE_64[(byte) data.charAt(charDex + 3)];
if (char1 < 0 || char2 < 0 || char3 == -1 || char4 == -1) {
// invalid character(-1), or bad padding (-2)
throw new IllegalArgumentException(SR.STRING_NOT_VALID);
}
int tVal = char1 << 18;
tVal += char2 << 12;
tVal += (char3 & 0xff) << 6;
tVal += char4 & 0xff;
if (char3 == -2) {
// two "==" pad chars, check bits 12-24
tVal &= 0x00FFF000;
retArray[byteDex++] = (byte) (tVal >> 16 & 0xFF);
}
else if (char4 == -2) {
// one pad char "=" , check bits 6-24.
tVal &= 0x00FFFFC0;
retArray[byteDex++] = (byte) (tVal >> 16 & 0xFF);
retArray[byteDex++] = (byte) (tVal >> 8 & 0xFF);
}
else {
// No pads take all 3 bytes, bits 0-24
retArray[byteDex++] = (byte) (tVal >> 16 & 0xFF);
retArray[byteDex++] = (byte) (tVal >> 8 & 0xFF);
retArray[byteDex++] = (byte) (tVal & 0xFF);
}
}
return retArray;
}
/**
* Decodes a given Base64 string into its corresponding byte array.
*
* @param data
* the Base64 string, as a String object, to decode
*
* @return the corresponding decoded byte array
* @throws IllegalArgumentException
* If the string is not a valid base64 encoded string
*/
public static Byte[] decodeAsByteObjectArray(final String data) {
int byteArrayLength = 3 * data.length() / 4;
if (data.endsWith("==")) {
byteArrayLength -= 2;
}
else if (data.endsWith("=")) {
byteArrayLength -= 1;
}
final Byte[] retArray = new Byte[byteArrayLength];
int byteDex = 0;
int charDex = 0;
for (; charDex < data.length(); charDex += 4) {
// get 4 chars, convert to 3 bytes
final int char1 = DECODE_64[(byte) data.charAt(charDex)];
final int char2 = DECODE_64[(byte) data.charAt(charDex + 1)];
final int char3 = DECODE_64[(byte) data.charAt(charDex + 2)];
final int char4 = DECODE_64[(byte) data.charAt(charDex + 3)];
if (char1 < 0 || char2 < 0 || char3 == -1 || char4 == -1) {
// invalid character(-1), or bad padding (-2)
throw new IllegalArgumentException(SR.STRING_NOT_VALID);
}
int tVal = char1 << 18;
tVal += char2 << 12;
tVal += (char3 & 0xff) << 6;
tVal += char4 & 0xff;
if (char3 == -2) {
// two "==" pad chars, check bits 12-24
tVal &= 0x00FFF000;
retArray[byteDex++] = (byte) (tVal >> 16 & 0xFF);
}
else if (char4 == -2) {
// one pad char "=" , check bits 6-24.
tVal &= 0x00FFFFC0;
retArray[byteDex++] = (byte) (tVal >> 16 & 0xFF);
retArray[byteDex++] = (byte) (tVal >> 8 & 0xFF);
}
else {
// No pads take all 3 bytes, bits 0-24
retArray[byteDex++] = (byte) (tVal >> 16 & 0xFF);
retArray[byteDex++] = (byte) (tVal >> 8 & 0xFF);
retArray[byteDex++] = (byte) (tVal & 0xFF);
}
}
return retArray;
}
/**
* Encodes a byte array as a Base64 string.
*
* @param data
* the byte array to encode
* @return the Base64-encoded string, as a String object
*/
public static String encode(final byte[] data) {
final StringBuilder builder = new StringBuilder();
final int dataRemainder = data.length % 3;
int j = 0;
int n = 0;
for (; j < data.length; j += 3) {
if (j < data.length - dataRemainder) {
n = ((data[j] & 0xFF) << 16) + ((data[j + 1] & 0xFF) << 8) + (data[j + 2] & 0xFF);
}
else {
if (dataRemainder == 1) {
n = (data[j] & 0xFF) << 16;
}
else if (dataRemainder == 2) {
n = ((data[j] & 0xFF) << 16) + ((data[j + 1] & 0xFF) << 8);
}
}
// Left here for readability
// byte char1 = (byte) ((n >>> 18) & 0x3F);
// byte char2 = (byte) ((n >>> 12) & 0x3F);
// byte char3 = (byte) ((n >>> 6) & 0x3F);
// byte char4 = (byte) (n & 0x3F);
builder.append(BASE_64_CHARS.charAt((byte) ((n >>> 18) & 0x3F)));
builder.append(BASE_64_CHARS.charAt((byte) ((n >>> 12) & 0x3F)));
builder.append(BASE_64_CHARS.charAt((byte) ((n >>> 6) & 0x3F)));
builder.append(BASE_64_CHARS.charAt((byte) (n & 0x3F)));
}
final int bLength = builder.length();
// append '=' to pad
if (data.length % 3 == 1) {
builder.replace(bLength - 2, bLength, "==");
}
else if (data.length % 3 == 2) {
builder.replace(bLength - 1, bLength, "=");
}
return builder.toString();
}
/**
* Encodes a byte array as a Base64 string.
*
* @param data
* the byte array to encode
* @return the Base64-encoded string, as a String object
*/
public static String encode(final Byte[] data) {
final StringBuilder builder = new StringBuilder();
final int dataRemainder = data.length % 3;
int j = 0;
int n = 0;
for (; j < data.length; j += 3) {
if (j < data.length - dataRemainder) {
n = ((data[j] & 0xFF) << 16) + ((data[j + 1] & 0xFF) << 8) + (data[j + 2] & 0xFF);
}
else {
if (dataRemainder == 1) {
n = (data[j] & 0xFF) << 16;
}
else if (dataRemainder == 2) {
n = ((data[j] & 0xFF) << 16) + ((data[j + 1] & 0xFF) << 8);
}
}
// Left here for readability
// byte char1 = (byte) ((n >>> 18) & 0x3F);
// byte char2 = (byte) ((n >>> 12) & 0x3F);
// byte char3 = (byte) ((n >>> 6) & 0x3F);
// byte char4 = (byte) (n & 0x3F);
builder.append(BASE_64_CHARS.charAt((byte) ((n >>> 18) & 0x3F)));
builder.append(BASE_64_CHARS.charAt((byte) ((n >>> 12) & 0x3F)));
builder.append(BASE_64_CHARS.charAt((byte) ((n >>> 6) & 0x3F)));
builder.append(BASE_64_CHARS.charAt((byte) (n & 0x3F)));
}
final int bLength = builder.length();
// append '=' to pad
if (data.length % 3 == 1) {
builder.replace(bLength - 2, bLength, "==");
}
else if (data.length % 3 == 2) {
builder.replace(bLength - 1, bLength, "=");
}
return builder.toString();
}
/**
* Determines whether the given string contains only Base64 characters.
*
* @param data
* the string, as a String object, to validate
* @return true if data is a valid Base64 string, otherwise false
*/
public static boolean validateIsBase64String(final String data) {
if (data == null || data.length() % 4 != 0) {
return false;
}
for (int m = 0; m < data.length(); m++) {
final byte charByte = (byte) data.charAt(m);
// pad char detected
if (DECODE_64[charByte] == -2) {
if (m < data.length() - 2) {
return false;
}
else if (m == data.length() - 2 && DECODE_64[(byte) data.charAt(m + 1)] != -2) {
return false;
}
}
if (charByte < 0 || DECODE_64[charByte] == -1) {
return false;
}
}
return true;
}
/**
* Private Default Ctor.
*/
private Base64() {
// No op
}
}
