public class Base32 extends Object {
private static final String base32Chars = "abcdefghijklmnopqrstuvwxyz234567";
private static final int[] base32Lookup = {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'
};
static public String encode(int version, byte[] payload) {
if (version < 0 || version > 255)
throw new IllegalArgumentException("Version not in range.");
// A stringified buffer is:
// 1 byte version + data bytes + 4 bytes check code (a truncated hash)
byte[] addressBytes = new byte[1 + payload.length + 4];
addressBytes[0] = (byte) version;
System.arraycopy(payload, 0, addressBytes, 1, payload.length);
byte[] checksum = Sha256Hash.hashTwice(addressBytes, 0, payload.length + 1);
System.arraycopy(checksum, 0, addressBytes, payload.length + 1, 4);
return encode(addressBytes);
}
/**
* 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 >= base32Lookup.length) {
continue;
}
digit = base32Lookup[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;
}
private static String toHex(byte[] decoded) {
StringBuffer sb = new StringBuffer();
sb.append("{");
for (int i = 0; i < decoded.length; i++) {
int b = decoded[i];
if (b < 0) {
b += 256;
}
sb.append("0x" + (Integer.toHexString(b + 256)).substring(1) + ",");
}
sb.deleteCharAt(sb.length() - 1);
sb.append("}");
return sb.toString();
}
}
Base32
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