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com.opslab.util.encrypt.Base32 Maven / Gradle / Ivy
package com.opslab.util.encrypt;
/**
* Base32的编码和解码
*/
public class Base32 {
private static final String ERR_CANONICAL = "Invalid Base32 string";
private static final char[] CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567".toCharArray();
private static final byte[] LOOKUP = {
26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, // 0123456789:;<=>?
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // @ABCDEFGHIJKLMNO
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, // PQRSTUVWXYZ[\]^_
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // `abcdefghijklmno
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 // pqrstuvwxyz
};
/**
* 使用Base32进行编码
*
* @param bytes
* @return
*/
public static String encode(final byte[] bytes) {
StringBuilder base32 = new StringBuilder((bytes.length * 8 + 4) / 5);
int currByte, digit, i = 0;
while (i < bytes.length) {
// STEP 0; insert new 5 bits, leave 3 bits
currByte = bytes[i++] & 255;
base32.append(CHARS[currByte >> 3]);
digit = (currByte & 7) << 2;
if (i >= bytes.length) {
base32.append(CHARS[digit]);
break;
}
// STEP 3: insert 2 new bits, then 5 bits, leave 1 bit
currByte = bytes[i++] & 255;
base32.append(CHARS[digit | (currByte >> 6)]);
base32.append(CHARS[(currByte >> 1) & 31]);
digit = (currByte & 1) << 4;
if (i >= bytes.length) {
base32.append(CHARS[digit]);
break;
}
// STEP 1: insert 4 new bits, leave 4 bit
currByte = bytes[i++] & 255;
base32.append(CHARS[digit | (currByte >> 4)]);
digit = (currByte & 15) << 1;
if (i >= bytes.length) {
base32.append(CHARS[digit]);
break;
}
// STEP 4: insert 1 new bit, then 5 bits, leave 2 bits
currByte = bytes[i++] & 255;
base32.append(CHARS[digit | (currByte >> 7)]);
base32.append(CHARS[(currByte >> 2) & 31]);
digit = (currByte & 3) << 3;
if (i >= bytes.length) {
base32.append(CHARS[digit]);
break;
}
// STEP 2: insert 3 new bits, then 5 bits, leave 0 bit
currByte = bytes[i++] & 255;
base32.append(CHARS[digit | (currByte >> 5)]);
base32.append(CHARS[currByte & 31]);
}
return base32.toString();
}
/**
* 用Base32进行解码
*
* @param base32
* @return
* @throws IllegalArgumentException
*/
public static String decode(final String base32) throws IllegalArgumentException {
switch (base32.length() % 8) {
case 1:
case 3:
case 6:
throw new IllegalArgumentException(ERR_CANONICAL);
}
byte[] bytes = new byte[base32.length() * 5 / 8];
int offset = 0, i = 0, lookup;
byte nextByte, digit;
while (i < base32.length()) {
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 0: leave 5 bits
nextByte = (byte) (digit << 3);
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 5: insert 3 bits, leave 2 bits
bytes[offset++] = (byte) (nextByte | (digit >> 2));
nextByte = (byte) ((digit & 3) << 6);
if (i >= base32.length()) {
if (nextByte != (byte) 0) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
break;
}
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 2: leave 7 bits
nextByte |= (byte) (digit << 1);
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 7: insert 1 bit, leave 4 bits
bytes[offset++] = (byte) (nextByte | (digit >> 4));
nextByte = (byte) ((digit & 15) << 4);
if (i >= base32.length()) {
if (nextByte != (byte) 0) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
break;
}
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 4: insert 4 bits, leave 1 bit
bytes[offset++] = (byte) (nextByte | (digit >> 1));
nextByte = (byte) ((digit & 1) << 7);
if (i >= base32.length()) {
if (nextByte != (byte) 0) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
break;
}
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 1: leave 6 bits
nextByte |= (byte) (digit << 2);
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 6: insert 2 bits, leave 3 bits
bytes[offset++] = (byte) (nextByte | (digit >> 3));
nextByte = (byte) ((digit & 7) << 5);
if (i >= base32.length()) {
if (nextByte != (byte) 0) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
break;
}
lookup = base32.charAt(i++) - '2';
if (lookup < 0 || lookup >= LOOKUP.length) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
digit = LOOKUP[lookup];
if (digit == -1) {
throw new IllegalArgumentException(ERR_CANONICAL);
}
// STEP n = 3: insert 5 bits, leave 0 bit
bytes[offset++] = (byte) (nextByte | digit);
}
return new String(bytes);
}
}
