gnu.crypto.util.Util Maven / Gradle / Ivy
package gnu.crypto.util;
// ----------------------------------------------------------------------------
// $Id: Util.java,v 1.10 2003/09/27 00:03:01 raif Exp $
//
// Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU Crypto is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING. If not, write to the
//
// Free Software Foundation Inc.,
// 59 Temple Place - Suite 330,
// Boston, MA 02111-1307
// USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module. An independent module is a module which is
// not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so. If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------
import java.math.BigInteger;
/**
*
* A collection of utility methods used throughout this project.
*
* @version $Revision: 1.10 $
*/
public class Util {
// Constants and variables
// -------------------------------------------------------------------------
// Hex charset
private static final char[] HEX_DIGITS = "0123456789ABCDEF".toCharArray();
// Base-64 charset
private static final String BASE64_CHARS
= "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
private static final char[] BASE64_CHARSET = BASE64_CHARS.toCharArray();
// Constructor(s)
// -------------------------------------------------------------------------
/**
* Trivial constructor to enforce Singleton pattern.
*/
private Util() {
super();
}
// Class methods
// -------------------------------------------------------------------------
/**
*
* Returns a string of hexadecimal digits from a byte array. Each byte is
* converted to 2 hex symbols; zero(es) included.
*
*
* This method calls the method with same name and three arguments as:
*
*
* toString(ba, 0, ba.length);
*
*
* @param ba the byte array to convert.
* @return a string of hexadecimal characters (two for each byte)
* representing the designated input byte array.
*/
public static String toString(byte[] ba) {
return toString(ba, 0, ba.length);
}
/**
*
* Returns a string of hexadecimal digits from a byte array, starting at
* offset and consisting of length bytes. Each
* byte is converted to 2 hex symbols; zero(es) included.
*
* @param ba the byte array to convert.
* @param offset the index from which to start considering the bytes to
* convert.
* @param length the count of bytes, starting from the designated offset to
* convert.
* @return a string of hexadecimal characters (two for each byte)
* representing the designated input byte sub-array.
*/
public static final String toString(byte[] ba, int offset, int length) {
char[] buf = new char[length * 2];
for (int i = 0, j = 0, k; i < length;) {
k = ba[offset + i++];
buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
buf[j++] = HEX_DIGITS[k & 0x0F];
}
return new String(buf);
}
/**
*
* Returns a string of hexadecimal digits from a byte array. Each byte is
* converted to 2 hex symbols; zero(es) included. The argument is treated as
* a large little-endian integer and is returned as a large big-endian
* integer.
*
*
* This method calls the method with same name and three arguments as:
*
*
* toReversedString(ba, 0, ba.length);
*
*
* @param ba the byte array to convert.
* @return a string of hexadecimal characters (two for each byte)
* representing the designated input byte array.
*/
public static String toReversedString(byte[] ba) {
return toReversedString(ba, 0, ba.length);
}
/**
*
* Returns a string of hexadecimal digits from a byte array, starting at
* offset and consisting of length bytes. Each
* byte is converted to 2 hex symbols; zero(es) included.
*
*
* The byte array is treated as a large little-endian integer, and is
* returned as a large big-endian integer.
*
* @param ba the byte array to convert.
* @param offset the index from which to start considering the bytes to
* convert.
* @param length the count of bytes, starting from the designated offset to
* convert.
* @return a string of hexadecimal characters (two for each byte)
* representing the designated input byte sub-array.
*/
public static final String
toReversedString(byte[] ba, int offset, int length) {
char[] buf = new char[length * 2];
for (int i = offset + length - 1, j = 0, k; i >= offset;) {
k = ba[offset + i--];
buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
buf[j++] = HEX_DIGITS[k & 0x0F];
}
return new String(buf);
}
/**
*
* Returns a byte array from a string of hexadecimal digits.
*
* @param s a string of hexadecimal ASCII characters
* @return the decoded byte array from the input hexadecimal string.
*/
public static byte[] toBytesFromString(String s) {
int limit = s.length();
byte[] result = new byte[((limit + 1) / 2)];
int i = 0, j = 0;
if ((limit % 2) == 1) {
result[j++] = (byte) fromDigit(s.charAt(i++));
}
while (i < limit) {
result[j] = (byte) (fromDigit(s.charAt(i++)) << 4);
result[j++] |= (byte) fromDigit(s.charAt(i++));
}
return result;
}
/**
*
* Returns a byte array from a string of hexadecimal digits, interpreting
* them as a large big-endian integer and returning it as a large
* little-endian integer.
*
* @param s a string of hexadecimal ASCII characters
* @return the decoded byte array from the input hexadecimal string.
*/
public static byte[] toReversedBytesFromString(String s) {
int limit = s.length();
byte[] result = new byte[((limit + 1) / 2)];
int i = 0;
if ((limit % 2) == 1) {
result[i++] = (byte) fromDigit(s.charAt(--limit));
}
while (limit > 0) {
result[i] = (byte) fromDigit(s.charAt(--limit));
result[i++] |= (byte) (fromDigit(s.charAt(--limit)) << 4);
}
return result;
}
/**
*
* Returns a number from 0 to 15 corresponding to
* the designated hexadecimal digit.
*
* @param c a hexadecimal ASCII symbol.
*/
public static int fromDigit(char c) {
if (c >= '0' && c <= '9') {
return c - '0';
} else if (c >= 'A' && c <= 'F') {
return c - 'A' + 10;
} else if (c >= 'a' && c <= 'f') {
return c - 'a' + 10;
} else {
throw new IllegalArgumentException("Invalid hexadecimal digit: " + c);
}
}
/**
*
* Returns a string of 8 hexadecimal digits (most significant digit first)
* corresponding to the unsigned integer n.
*
* @param n the unsigned integer to convert.
* @return a hexadecimal string 8-character long.
*/
public static String toString(int n) {
char[] buf = new char[8];
for (int i = 7; i >= 0; i--) {
buf[i] = HEX_DIGITS[n & 0x0F];
n >>>= 4;
}
return new String(buf);
}
/**
*
* Returns a string of hexadecimal digits from an integer array. Each int is
* converted to 4 hex symbols.
*/
public static String toString(int[] ia) {
int length = ia.length;
char[] buf = new char[length * 8];
for (int i = 0, j = 0, k; i < length; i++) {
k = ia[i];
buf[j++] = HEX_DIGITS[(k >>> 28) & 0x0F];
buf[j++] = HEX_DIGITS[(k >>> 24) & 0x0F];
buf[j++] = HEX_DIGITS[(k >>> 20) & 0x0F];
buf[j++] = HEX_DIGITS[(k >>> 16) & 0x0F];
buf[j++] = HEX_DIGITS[(k >>> 12) & 0x0F];
buf[j++] = HEX_DIGITS[(k >>> 8) & 0x0F];
buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
buf[j++] = HEX_DIGITS[k & 0x0F];
}
return new String(buf);
}
/**
*
* Returns a string of 16 hexadecimal digits (most significant digit first)
* corresponding to the unsigned long n.
*
* @param n the unsigned long to convert.
* @return a hexadecimal string 16-character long.
*/
public static String toString(long n) {
char[] b = new char[16];
for (int i = 15; i >= 0; i--) {
b[i] = HEX_DIGITS[(int) (n & 0x0FL)];
n >>>= 4;
}
return new String(b);
}
/**
*
* Similar to the toString() method except that the Unicode
* escape character is inserted before every pair of bytes. Useful to
* externalise byte arrays that will be constructed later from such strings;
* eg. s-box values.
*
* @throws ArrayIndexOutOfBoundsException if the length is odd.
*/
public static String toUnicodeString(byte[] ba) {
return toUnicodeString(ba, 0, ba.length);
}
/**
*
* Similar to the toString() method except that the Unicode
* escape character is inserted before every pair of bytes. Useful to
* externalise byte arrays that will be constructed later from such strings;
* eg. s-box values.
*
* @throws ArrayIndexOutOfBoundsException if the length is odd.
*/
public static final String
toUnicodeString(byte[] ba, int offset, int length) {
StringBuffer sb = new StringBuffer();
int i = 0;
int j = 0;
int k;
sb.append('\n').append("\"");
while (i < length) {
sb.append("\\u");
k = ba[offset + i++];
sb.append(HEX_DIGITS[(k >>> 4) & 0x0F]);
sb.append(HEX_DIGITS[k & 0x0F]);
k = ba[offset + i++];
sb.append(HEX_DIGITS[(k >>> 4) & 0x0F]);
sb.append(HEX_DIGITS[k & 0x0F]);
if ((++j % 8) == 0) {
sb.append("\"+").append('\n').append("\"");
}
}
sb.append("\"").append('\n');
return sb.toString();
}
/**
*
* Similar to the toString() method except that the Unicode
* escape character is inserted before every pair of bytes. Useful to
* externalise integer arrays that will be constructed later from such
* strings; eg. s-box values.
*
* @throws ArrayIndexOutOfBoundsException if the length is not a multiple of
* 4.
*/
public static String toUnicodeString(int[] ia) {
StringBuffer sb = new StringBuffer();
int i = 0;
int j = 0;
int k;
sb.append('\n').append("\"");
while (i < ia.length) {
k = ia[i++];
sb.append("\\u");
sb.append(HEX_DIGITS[(k >>> 28) & 0x0F]);
sb.append(HEX_DIGITS[(k >>> 24) & 0x0F]);
sb.append(HEX_DIGITS[(k >>> 20) & 0x0F]);
sb.append(HEX_DIGITS[(k >>> 16) & 0x0F]);
sb.append("\\u");
sb.append(HEX_DIGITS[(k >>> 12) & 0x0F]);
sb.append(HEX_DIGITS[(k >>> 8) & 0x0F]);
sb.append(HEX_DIGITS[(k >>> 4) & 0x0F]);
sb.append(HEX_DIGITS[k & 0x0F]);
if ((++j % 4) == 0) {
sb.append("\"+").append('\n').append("\"");
}
}
sb.append("\"").append('\n');
return sb.toString();
}
public static byte[] toBytesFromUnicode(String s) {
int limit = s.length() * 2;
byte[] result = new byte[limit];
char c;
for (int i = 0; i < limit; i++) {
c = s.charAt(i >>> 1);
result[i] = (byte) (((i & 1) == 0) ? c >>> 8 : c);
}
return result;
}
/**
*
* Dumps a byte array as a string, in a format that is easy to read for
* debugging. The string m is prepended to the start of each
* line.
*
*
* If offset and length are omitted, the whole
* array is used. If m is omitted, nothing is prepended to each
* line.
*
* @param data the byte array to be dumped.
* @param offset the offset within data to start from.
* @param length the number of bytes to dump.
* @param m a string to be prepended to each line.
* @return a string containing the result.
*/
public static String dumpString(byte[] data, int offset, int length, String m) {
if (data == null) {
return m + "null\n";
}
StringBuffer sb = new StringBuffer(length * 3);
if (length > 32) {
sb.append(m).append("Hexadecimal dump of ").append(length).append(" bytes...\n");
}
// each line will list 32 bytes in 4 groups of 8 each
int end = offset + length;
String s;
int l = Integer.toString(length).length();
if (l < 4) {
l = 4;
}
for (; offset < end; offset += 32) {
if (length > 32) {
s = " " + offset;
sb.append(m).append(s.substring(s.length() - l)).append(": ");
}
int i = 0;
for (; i < 32 && offset + i + 7 < end; i += 8) {
sb.append(toString(data, offset + i, 8)).append(' ');
}
if (i < 32) {
for (; i < 32 && offset + i < end; i++) {
sb.append(byteToString(data[offset + i]));
}
}
sb.append('\n');
}
return sb.toString();
}
public static String dumpString(byte[] data) {
return (data == null) ? "null\n" : dumpString(data, 0, data.length, "");
}
public static String dumpString(byte[] data, String m) {
return (data == null) ? "null\n" : dumpString(data, 0, data.length, m);
}
public static String dumpString(byte[] data, int offset, int length) {
return dumpString(data, offset, length, "");
}
/**
*
* Returns a string of 2 hexadecimal digits (most significant digit first)
* corresponding to the lowest 8 bits of n.
*
* @param n the byte value to convert.
* @return a string of 2 hex characters representing the input.
*/
public static String byteToString(int n) {
char[] buf = {HEX_DIGITS[(n >>> 4) & 0x0F], HEX_DIGITS[n & 0x0F]};
return new String(buf);
}
/**
*
* Converts a designated byte array to a Base-64 representation, with the
* exceptions that (a) leading 0-byte(s) are ignored, and (b) the character
* '.' (dot) shall be used instead of "+' (plus).
*
*
* Used by SASL password file manipulation primitives.
*
* @param buffer an arbitrary sequence of bytes to represent in Base-64.
* @return unpadded (without the '=' character(s)) Base-64 representation of
* the input.
*/
public static final String toBase64(byte[] buffer) {
int len = buffer.length, pos = len % 3;
byte b0 = 0, b1 = 0, b2 = 0;
switch (pos) {
case 1:
b2 = buffer[0];
break;
case 2:
b1 = buffer[0];
b2 = buffer[1];
break;
}
StringBuffer sb = new StringBuffer();
int c;
boolean notleading = false;
do {
c = (b0 & 0xFC) >>> 2;
if (notleading || c != 0) {
sb.append(BASE64_CHARSET[c]);
notleading = true;
}
c = ((b0 & 0x03) << 4) | ((b1 & 0xF0) >>> 4);
if (notleading || c != 0) {
sb.append(BASE64_CHARSET[c]);
notleading = true;
}
c = ((b1 & 0x0F) << 2) | ((b2 & 0xC0) >>> 6);
if (notleading || c != 0) {
sb.append(BASE64_CHARSET[c]);
notleading = true;
}
c = b2 & 0x3F;
if (notleading || c != 0) {
sb.append(BASE64_CHARSET[c]);
notleading = true;
}
if (pos >= len) {
break;
} else {
try {
b0 = buffer[pos++];
b1 = buffer[pos++];
b2 = buffer[pos++];
} catch (ArrayIndexOutOfBoundsException x) {
break;
}
}
} while (true);
if (notleading) {
return sb.toString();
}
return "0";
}
/**
*
* The inverse function of the above.
*
*
* Converts a string representing the encoding of some bytes in Base-64 to
* their original form.
*
* @param str the Base-64 encoded representation of some byte(s).
* @return the bytes represented by the str.
* @throws NumberFormatException if str is null,
* or str contains an illegal Base-64 character.
* @see #toBase64(byte[])
*/
public static final byte[] fromBase64(String str) {
int len = str.length();
if (len == 0) {
throw new NumberFormatException("Empty string");
}
byte[] a = new byte[len + 1];
int i, j;
for (i = 0; i < len; i++) {
try {
a[i] = (byte) BASE64_CHARS.indexOf(str.charAt(i));
} catch (ArrayIndexOutOfBoundsException x) {
throw new NumberFormatException("Illegal character at #" + i);
}
}
i = len - 1;
j = len;
try {
while (true) {
a[j] = a[i];
if (--i < 0) {
break;
}
a[j] |= (a[i] & 0x03) << 6;
j--;
a[j] = (byte) ((a[i] & 0x3C) >>> 2);
if (--i < 0) {
break;
}
a[j] |= (a[i] & 0x0F) << 4;
j--;
a[j] = (byte) ((a[i] & 0x30) >>> 4);
if (--i < 0) {
break;
}
a[j] |= (a[i] << 2);
j--;
a[j] = 0;
if (--i < 0) {
break;
}
}
} catch (Exception ignored) {
}
try { // ignore leading 0-bytes
while (a[j] == 0) {
j++;
}
} catch (Exception x) {
return new byte[1]; // one 0-byte
}
byte[] result = new byte[len - j + 1];
System.arraycopy(a, j, result, 0, len - j + 1);
return result;
}
// BigInteger utilities ----------------------------------------------------
/**
*
* Treats the input as the MSB representation of a number, and discards
* leading zero elements. For efficiency, the input is simply returned if no
* leading zeroes are found.
*
* @param n the {@link BigInteger} to trim.
* @return the byte array representation of the designated
* {@link BigInteger} with no leading 0-bytes.
*/
public static final byte[] trim(BigInteger n) {
byte[] in = n.toByteArray();
if (in.length == 0 || in[0] != 0) {
return in;
}
int len = in.length;
int i = 1;
while (in[i] == 0 && i < len) {
++i;
}
byte[] result = new byte[len - i];
System.arraycopy(in, i, result, 0, len - i);
return result;
}
/**
*
* Returns a hexadecimal dump of the trimmed bytes of a {@link BigInteger}.
*
*
* @param x the {@link BigInteger} to display.
* @return the string representation of the designated {@link BigInteger}.
*/
public static final String dump(BigInteger x) {
return dumpString(trim(x));
}
}