package uc.crypto;
public final class BASE32Encoder {
private BASE32Encoder(){}
private static final String BASE32CHARS =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
private static final int[] BASE_32_LOOKUP =
{ 0xFF,0xFF,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F, // '0', '1', '2', '3', '4', '5', '6', '7'
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, // '8', '9', ':', ';', '<', '=', '>', '?'
0xFF,0x00,0x01,0x02,0x03,0x04,0x05,0x06, // '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G'
0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E, // 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O'
0x0F,0x10,0x11,0x12,0x13,0x14,0x15,0x16, // 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W'
0x17,0x18,0x19,0xFF,0xFF,0xFF,0xFF,0xFF, // 'X', 'Y', 'Z', '[', '\', ']', '^', '_'
0xFF,0x00,0x01,0x02,0x03,0x04,0x05,0x06, // '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g'
0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E, // 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o'
0x0F,0x10,0x11,0x12,0x13,0x14,0x15,0x16, // 'p', 'q', 'r', 's', 't', 'u', 'v', 'w'
0x17,0x18,0x19,0xFF,0xFF,0xFF,0xFF,0xFF // 'x', 'y', 'z', '{', '|', '}', '~', 'DEL'
};
/**
* Encodes byte array to Base32 String.
*
* @param bytes Bytes to encode.
* @return Encoded byte array <code>bytes</code> as a String.
*
*/
static public String encode(final byte[] bytes) {
int i = 0, index = 0, digit = 0;
int currByte, nextByte;
StringBuffer base32 = new StringBuffer((bytes.length + 7) * 8 / 5);
while (i < bytes.length) {
currByte = (bytes[i] >= 0) ? bytes[i] : (bytes[i] + 256); // unsign
/* Is the current digit going to span a byte boundary? */
if (index > 3) {
if ((i + 1) < bytes.length) {
nextByte =
(bytes[i + 1] >= 0) ? bytes[i + 1] : (bytes[i + 1] + 256);
} else {
nextByte = 0;
}
digit = currByte & (0xFF >> index);
index = (index + 5) % 8;
digit <<= index;
digit |= nextByte >> (8 - index);
i++;
} else {
digit = (currByte >> (8 - (index + 5))) & 0x1F;
index = (index + 5) % 8;
if (index == 0)
i++;
}
base32.append(BASE32CHARS.charAt(digit));
}
return base32.toString();
}
/**
* Decodes the given Base32 String to a raw byte array.
*
* @param base32
* @return Decoded <code>base32</code> String as a raw byte array.
*/
static public byte[] decode(final String base32) {
int i, index, lookup, offset, digit;
byte[] bytes = new byte[base32.length() * 5 / 8];
for (i = 0, index = 0, offset = 0; i < base32.length(); i++) {
lookup = base32.charAt(i) - '0';
/* Skip chars outside the lookup table */
if (lookup < 0 || lookup >= BASE_32_LOOKUP.length) {
continue;
}
digit = BASE_32_LOOKUP[lookup];
/* If this digit is not in the table, ignore it */
if (digit == 0xFF) {
continue;
}
if (index <= 3) {
index = (index + 5) % 8;
if (index == 0) {
bytes[offset] |= digit;
offset++;
if (offset >= bytes.length)
break;
} else {
bytes[offset] |= digit << (8 - index);
}
} else {
index = (index + 5) % 8;
bytes[offset] |= (digit >>> index);
offset++;
if (offset >= bytes.length) {
break;
}
bytes[offset] |= digit << (8 - index);
}
}
return bytes;
}
public static void main(String[] args){
//Test
String test="L66Q4YVNAFWVS23X2HJIRA5ZJ7WXR3F26RSASFA";
//System.out.println(test);
// System.out.println( BASE32Encoder.encode(BASE32Encoder.decode(test)) );
for (int i = 1; i < test.length() -1 ; i++) {
// System.out.println( BASE32Encoder.encode(BASE32Encoder.decode(test.substring(i))) );
}
}
}