Class Base32

src/main/java/org/apache/commons/codec/binary/Base32.java:43–582

Provides Base32 encoding and decoding as defined by RFC 4648 . The class can be parameterized in the following manner with various constructors: Whether to use the "base32hex" variant instead of the default "base32" Line le

 * @since 1.5
 */
public class Base32 extends BaseNCodec {

    /**
     * BASE32 characters are 5 bits in length.
     * They are formed by taking a block of five octets to form a 40-bit string,
     * which is converted into eight BASE32 characters.
     */
    private static final int BITS_PER_ENCODED_BYTE = 5;
    private static final int BYTES_PER_ENCODED_BLOCK = 8;
    private static final int BYTES_PER_UNENCODED_BLOCK = 5;

    /**
     * Chunk separator per RFC 2045 section 2.1.
     *
     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
     */
    private static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};

    /**
     * This array is a lookup table that translates Unicode characters drawn from the "Base32 Alphabet" (as specified
     * in Table 3 of RFC 4648) into their 5-bit positive integer equivalents. Characters that are not in the Base32
     * alphabet but fall within the bounds of the array are translated to -1.
     */
    private static final byte[] DECODE_TABLE = {
         //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20-2f
            -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, // 30-3f 2-7
            -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, // 40-4f A-O
            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,                     // 50-5a P-Z
                                                        -1, -1, -1, -1, -1, // 5b - 5f
            -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, // 60 - 6f a-o
            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,                     // 70 - 7a p-z/**/
    };

    /**
     * This array is a lookup table that translates 5-bit positive integer index values into their "Base32 Alphabet"
     * equivalents as specified in Table 3 of RFC 4648.
     */
    private static final byte[] ENCODE_TABLE = {
            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
            'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
            '2', '3', '4', '5', '6', '7',
    };

    /**
     * This array is a lookup table that translates Unicode characters drawn from the "Base32 Hex Alphabet" (as
     * specified in Table 4 of RFC 4648) into their 5-bit positive integer equivalents. Characters that are not in the
     * Base32 Hex alphabet but fall within the bounds of the array are translated to -1.
     */
    private static final byte[] HEX_DECODE_TABLE = {
         //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20-2f
             0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, // 30-3f 2-7
            -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 40-4f A-O