Package org.apache.commons.codec.binary

Class Base32

  • All Implemented Interfaces:
    BinaryDecoder, BinaryEncoder, Decoder, Encoder
    public class Base32
extends BaseNCodec
    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 length: Default 76. Line length that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
    • Line separator: Default is CRLF ("\r\n")

    This class operates directly on byte streams, and not character streams.

    This class is thread-safe.

    To configure a new instance, use a Base32.Builder. For example: 

     Base32 base32 = Base32.builder()
   .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient
   .setLineLength(0)                          // default is none
   .setLineSeparator('\r', '\n')              // default is CR LF
   .setPadding('=')                           // default is '='
   .setEncodeTable(customEncodeTable)         // default is RFC 4648 Section 6, Table 3: The Base 32 Alphabet
   .get()
    Since:
    1.5
    See Also:
    Base32InputStream, Base32OutputStream, RFC 4648

    • Field Detail

      • BITS_PER_ENCODED_BYTE

        private static final int BITS_PER_ENCODED_BYTE
        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.
        See Also:
        Constant Field Values

      • BYTES_PER_ENCODED_BLOCK

        private static final int BYTES_PER_ENCODED_BLOCK
        See Also:
        Constant Field Values

      • BYTES_PER_UNENCODED_BLOCK

        private static final int BYTES_PER_UNENCODED_BLOCK
        See Also:
        Constant Field Values

      • DECODE_TABLE

        private static final byte[] DECODE_TABLE
        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.

      • HEX_DECODE_TABLE

        private static final byte[] HEX_DECODE_TABLE
        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.

      • MASK_5_BITS

        private static final int MASK_5_BITS
        Mask used to extract 5 bits, used when encoding Base32 bytes
        See Also:
        Constant Field Values

      • MASK_4_BITS

        private static final long MASK_4_BITS
        Mask used to extract 4 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values

      • MASK_3_BITS

        private static final long MASK_3_BITS
        Mask used to extract 3 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values

      • MASK_2_BITS

        private static final long MASK_2_BITS
        Mask used to extract 2 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values

      • MASK_1_BITS

        private static final long MASK_1_BITS
        Mask used to extract 1 bits, used when decoding final trailing character.
        See Also:
        Constant Field Values

      • encodeSize

        private final int encodeSize
        Convenience variable to help us determine when our buffer is going to run out of room and needs resizing. encodeSize = {@link #BYTES_PER_ENCODED_BLOCK} + lineSeparator.length;

      • lineSeparator

        private final byte[] lineSeparator
        Line separator for encoding. Not used when decoding. Only used if lineLength > 0.

    • Constructor Detail

      • Base32

        public Base32()
        Constructs a Base32 codec used for decoding and encoding.

        When encoding the line length is 0 (no chunking).

      • Base32

        @Deprecated
public Base32​(byte pad)
        Deprecated.
        Use builder() and Base32.Builder.
        Constructs a Base32 codec used for decoding and encoding.

        When encoding the line length is 0 (no chunking).

        Parameters:
        pad - byte used as padding byte.

      • Base32

        @Deprecated
public Base32​(int lineLength)
        Deprecated.
        Use builder() and Base32.Builder.
        Constructs a Base32 codec used for decoding and encoding.

        When encoding the line length is given in the constructor, the line separator is CRLF.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.

      • Base32

        @Deprecated
public Base32​(int lineLength,
              byte[] lineSeparator)
        Deprecated.
        Use builder() and Base32.Builder.
        Constructs a Base32 codec used for decoding and encoding.

        When encoding the line length and line separator are given in the constructor.

        Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        lineSeparator - Each line of encoded data will end with this sequence of bytes.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters.

      • Base32

        @Deprecated
public Base32​(int lineLength,
              byte[] lineSeparator,
              boolean useHex)
        Deprecated.
        Use builder() and Base32.Builder.
        Constructs a Base32 / Base32 Hex codec used for decoding and encoding.

        When encoding the line length and line separator are given in the constructor.

        Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        lineSeparator - Each line of encoded data will end with this sequence of bytes.
        useHex -
        Throws:
        java.lang.IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters. Or the lineLength > 0 and lineSeparator is null.

      • Base32

        @Deprecated
public Base32​(int lineLength,
              byte[] lineSeparator,
              boolean useHex,
              byte padding)
        Deprecated.
        Use builder() and Base32.Builder.
        Constructs a Base32 / Base32 Hex codec used for decoding and encoding.

        When encoding the line length and line separator are given in the constructor.

        Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        lineSeparator - Each line of encoded data will end with this sequence of bytes.
        useHex -
        padding - padding byte.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters. Or the lineLength > 0 and lineSeparator is null.

      • Base32

        @Deprecated
public Base32​(int lineLength,
              byte[] lineSeparator,
              boolean useHex,
              byte padding,
              CodecPolicy decodingPolicy)
        Deprecated.
        Use builder() and Base32.Builder.
        Constructs a Base32 / Base32 Hex codec used for decoding and encoding.

        When encoding the line length and line separator are given in the constructor.

        Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.

        Parameters:
        lineLength - Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
        lineSeparator - Each line of encoded data will end with this sequence of bytes.
        useHex -
        padding - padding byte.
        decodingPolicy - The decoding policy.
        Throws:
        java.lang.IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters. Or the lineLength > 0 and lineSeparator is null.
        Since:
        1.15

    • Method Detail

      • builder

        public static Base32.Builder builder()
        Creates a new Builder.

        To configure a new instance, use a Base32.Builder. For example: 

         Base32 base32 = Base32.builder()
   .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient
   .setLineLength(0)                          // default is none
   .setLineSeparator('\r', '\n')              // default is CR LF
   .setPadding('=')                           // default is '='
   .setEncodeTable(customEncodeTable)         // default is RFC 4648 Section 6, Table 3: The Base 32 Alphabet
   .get()
        Returns:
        a new Builder.
        Since:
        1.17.0

      • decodeTable

        private static byte[] decodeTable​(boolean useHex)

      • decode

        void decode​(byte[] input,
            int inPos,
            int inAvail,
            BaseNCodec.Context context)

        Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1" call is not necessary when decoding, but it doesn't hurt, either.

        Ignores all non-Base32 characters. This is how chunked (for example 76 character) data is handled, since CR and LF are silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in, garbage-out philosophy: it will not check the provided data for validity.

        Output is written to Context#buffer as 8-bit octets, using Context#pos as the buffer position

        Specified by:
        decode in class BaseNCodec
        Parameters:
        input - byte[] array of ASCII data to Base32 decode.
        inPos - Position to start reading data from.
        inAvail - Amount of bytes available from input for decoding.
        context - the context to be used.

      • encode

        void encode​(byte[] input,
            int inPos,
            int inAvail,
            BaseNCodec.Context context)

        Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last remaining bytes (if not multiple of 5).

        Specified by:
        encode in class BaseNCodec
        Parameters:
        input - byte[] array of binary data to Base32 encode.
        inPos - Position to start reading data from.
        inAvail - Amount of bytes available from input for encoding.
        context - the context to be used.

      • getLineSeparator

        byte[] getLineSeparator()
        Gets the line separator (for testing only).
        Returns:
        the line separator.

      • isInAlphabet

        public boolean isInAlphabet​(byte octet)
        Returns whether or not the octet is in the Base32 alphabet.
        Specified by:
        isInAlphabet in class BaseNCodec
        Parameters:
        octet - The value to test.
        Returns:
        true if the value is defined in the Base32 alphabet false otherwise.

      • validateCharacter

        private void validateCharacter​(long emptyBitsMask,
                               BaseNCodec.Context context)
        Validates whether decoding the final trailing character is possible in the context of the set of possible Base32 values.

        The character is valid if the lower bits within the provided mask are zero. This is used to test the final trailing base-32 digit is zero in the bits that will be discarded.

        Parameters:
        emptyBitsMask - The mask of the lower bits that should be empty.
        context - the context to be used.
        Throws:
        java.lang.IllegalArgumentException - if the bits being checked contain any non-zero value.

      • validateTrailingCharacters

        private void validateTrailingCharacters()
        Validates whether decoding allows final trailing characters that cannot be created during encoding.
        Throws:
        java.lang.IllegalArgumentException - if strict decoding is enabled.