245 lines
9.8 KiB
Java
245 lines
9.8 KiB
Java
/*
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* @(#)Base64.java 1.5 03/12/19
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*
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* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*/
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package de.hsadmin.cli;
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/**
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* Static methods for translating Base64 encoded strings to byte arrays
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* and vice-versa.
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*
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* @author Josh Bloch
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* @version 1.5, 12/19/03
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* @see Preferences
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* @since 1.4
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*/
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class Base64 {
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/**
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* Translates the specified byte array into a Base64 string as per
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* Preferences.put(byte[]).
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*/
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static String byteArrayToBase64(byte[] a) {
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return byteArrayToBase64(a, false);
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}
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/**
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* Translates the specified byte array into an "aternate representation"
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* Base64 string. This non-standard variant uses an alphabet that does
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* not contain the uppercase alphabetic characters, which makes it
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* suitable for use in situations where case-folding occurs.
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*/
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static String byteArrayToAltBase64(byte[] a) {
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return byteArrayToBase64(a, true);
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}
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private static String byteArrayToBase64(byte[] a, boolean alternate) {
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int aLen = a.length;
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int numFullGroups = aLen/3;
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int numBytesInPartialGroup = aLen - 3*numFullGroups;
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int resultLen = 4*((aLen + 2)/3);
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StringBuffer result = new StringBuffer(resultLen);
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char[] intToAlpha = (alternate ? intToAltBase64 : intToBase64);
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// Translate all full groups from byte array elements to Base64
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int inCursor = 0;
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for (int i=0; i<numFullGroups; i++) {
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int byte0 = a[inCursor++] & 0xff;
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int byte1 = a[inCursor++] & 0xff;
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int byte2 = a[inCursor++] & 0xff;
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result.append(intToAlpha[byte0 >> 2]);
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result.append(intToAlpha[(byte0 << 4)&0x3f | (byte1 >> 4)]);
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result.append(intToAlpha[(byte1 << 2)&0x3f | (byte2 >> 6)]);
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result.append(intToAlpha[byte2 & 0x3f]);
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}
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// Translate partial group if present
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if (numBytesInPartialGroup != 0) {
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int byte0 = a[inCursor++] & 0xff;
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result.append(intToAlpha[byte0 >> 2]);
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if (numBytesInPartialGroup == 1) {
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result.append(intToAlpha[(byte0 << 4) & 0x3f]);
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result.append("==");
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} else {
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// assert numBytesInPartialGroup == 2;
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int byte1 = a[inCursor++] & 0xff;
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result.append(intToAlpha[(byte0 << 4)&0x3f | (byte1 >> 4)]);
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result.append(intToAlpha[(byte1 << 2)&0x3f]);
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result.append('=');
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}
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}
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// assert inCursor == a.length;
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// assert result.length() == resultLen;
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return result.toString();
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}
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/**
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* This array is a lookup table that translates 6-bit positive integer
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* index values into their "Base64 Alphabet" equivalents as specified
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* in Table 1 of RFC 2045.
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*/
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private static final char intToBase64[] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
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'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
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};
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/**
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* This array is a lookup table that translates 6-bit positive integer
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* index values into their "Alternate Base64 Alphabet" equivalents.
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* This is NOT the real Base64 Alphabet as per in Table 1 of RFC 2045.
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* This alternate alphabet does not use the capital letters. It is
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* designed for use in environments where "case folding" occurs.
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*/
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private static final char intToAltBase64[] = {
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'!', '"', '#', '$', '%', '&', '\'', '(', ')', ',', '-', '.', ':',
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';', '<', '>', '@', '[', ']', '^', '`', '_', '{', '|', '}', '~',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '?'
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};
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/**
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* Translates the specified Base64 string (as per Preferences.get(byte[]))
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* into a byte array.
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*
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* @throw IllegalArgumentException if <tt>s</tt> is not a valid Base64
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* string.
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*/
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static byte[] base64ToByteArray(String s) {
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return base64ToByteArray(s, false);
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}
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/**
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* Translates the specified "aternate representation" Base64 string
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* into a byte array.
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*
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* @throw IllegalArgumentException or ArrayOutOfBoundsException
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* if <tt>s</tt> is not a valid alternate representation
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* Base64 string.
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*/
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static byte[] altBase64ToByteArray(String s) {
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return base64ToByteArray(s, true);
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}
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private static byte[] base64ToByteArray(String s, boolean alternate) {
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byte[] alphaToInt = (alternate ? altBase64ToInt : base64ToInt);
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int sLen = s.length();
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int numGroups = sLen/4;
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if (4*numGroups != sLen)
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throw new IllegalArgumentException(
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"String length must be a multiple of four.");
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int missingBytesInLastGroup = 0;
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int numFullGroups = numGroups;
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if (sLen != 0) {
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if (s.charAt(sLen-1) == '=') {
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missingBytesInLastGroup++;
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numFullGroups--;
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}
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if (s.charAt(sLen-2) == '=')
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missingBytesInLastGroup++;
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}
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byte[] result = new byte[3*numGroups - missingBytesInLastGroup];
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// Translate all full groups from base64 to byte array elements
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int inCursor = 0, outCursor = 0;
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for (int i=0; i<numFullGroups; i++) {
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int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch3 = base64toInt(s.charAt(inCursor++), alphaToInt);
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result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
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result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
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result[outCursor++] = (byte) ((ch2 << 6) | ch3);
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}
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// Translate partial group, if present
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if (missingBytesInLastGroup != 0) {
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int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
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result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
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if (missingBytesInLastGroup == 1) {
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int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
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result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
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}
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}
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// assert inCursor == s.length()-missingBytesInLastGroup;
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// assert outCursor == result.length;
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return result;
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}
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/**
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* Translates the specified character, which is assumed to be in the
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* "Base 64 Alphabet" into its equivalent 6-bit positive integer.
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*
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* @throw IllegalArgumentException or ArrayOutOfBoundsException if
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* c is not in the Base64 Alphabet.
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*/
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private static int base64toInt(char c, byte[] alphaToInt) {
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int result = alphaToInt[c];
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if (result < 0)
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throw new IllegalArgumentException("Illegal character " + c);
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return result;
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}
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/**
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* This array is a lookup table that translates unicode characters
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* drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045)
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* into their 6-bit positive integer equivalents. Characters that
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* are not in the Base64 alphabet but fall within the bounds of the
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* array are translated to -1.
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*/
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private static final byte base64ToInt[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54,
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55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
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5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
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24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
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35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
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};
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/**
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* This array is the analogue of base64ToInt, but for the nonstandard
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* variant that avoids the use of uppercase alphabetic characters.
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*/
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private static final byte altBase64ToInt[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1,
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2, 3, 4, 5, 6, 7, 8, -1, 62, 9, 10, 11, -1 , 52, 53, 54, 55, 56, 57,
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58, 59, 60, 61, 12, 13, 14, -1, 15, 63, 16, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, 17, -1, 18, 19, 21, 20, 26, 27, 28, 29, 30, 31, 32, 33,
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34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
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51, 22, 23, 24, 25
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};
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public static void main(String args[]) {
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int numRuns = Integer.parseInt(args[0]);
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int numBytes = Integer.parseInt(args[1]);
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java.util.Random rnd = new java.util.Random();
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for (int i=0; i<numRuns; i++) {
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for (int j=0; j<numBytes; j++) {
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byte[] arr = new byte[j];
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for (int k=0; k<j; k++)
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arr[k] = (byte)rnd.nextInt();
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String s = byteArrayToBase64(arr);
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byte [] b = base64ToByteArray(s);
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if (!java.util.Arrays.equals(arr, b))
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System.out.println("Dismal failure!");
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s = byteArrayToAltBase64(arr);
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b = altBase64ToByteArray(s);
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if (!java.util.Arrays.equals(arr, b))
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System.out.println("Alternate dismal failure!");
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}
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}
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}
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}
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