Class Base32

java.lang.Object
org.apache.commons.codec.binary.BaseNCodec
org.apache.commons.codec.binary.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.

Since:
1.5
See Also:
  • Nested Class Summary

    Nested classes/interfaces inherited from class org.apache.commons.codec.binary.BaseNCodec

    BaseNCodec.Context
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final int
    BASE32 characters are 5 bits in length.
    private static final int
     
    private static final int
     
    private static final byte[]
    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.
    private final int
    Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
    private final byte[]
    Decode table to use.
    private static final byte[]
    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 final int
    Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
    private final byte[]
    Encode table to use.
    private static final byte[]
    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.
    private static final byte[]
    This array is a lookup table that translates 5-bit positive integer index values into their "Base32 Hex Alphabet" equivalents as specified in Table 4 of RFC 4648.
    private final byte[]
    Line separator for encoding.
    private static final long
    Mask used to extract 1 bits, used when decoding final trailing character.
    private static final long
    Mask used to extract 2 bits, used when decoding final trailing character.
    private static final long
    Mask used to extract 3 bits, used when decoding final trailing character.
    private static final long
    Mask used to extract 4 bits, used when decoding final trailing character.
    private static final int
    Mask used to extract 5 bits, used when encoding Base32 bytes

    Fields inherited from class org.apache.commons.codec.binary.BaseNCodec

    CHUNK_SEPARATOR, DECODING_POLICY_DEFAULT, EOF, lineLength, MASK_8BITS, MIME_CHUNK_SIZE, pad, PAD, PAD_DEFAULT, PEM_CHUNK_SIZE
  • Constructor Summary

    Constructors
    Constructor
    Description
    Creates a Base32 codec used for decoding and encoding.
    Base32(boolean useHex)
    Creates a Base32 codec used for decoding and encoding.
    Base32(boolean useHex, byte padding)
    Creates a Base32 codec used for decoding and encoding.
    Base32(byte pad)
    Creates a Base32 codec used for decoding and encoding.
    Base32(int lineLength)
    Creates a Base32 codec used for decoding and encoding.
    Base32(int lineLength, byte[] lineSeparator)
    Creates a Base32 codec used for decoding and encoding.
    Base32(int lineLength, byte[] lineSeparator, boolean useHex)
    Creates a Base32 / Base32 Hex codec used for decoding and encoding.
    Base32(int lineLength, byte[] lineSeparator, boolean useHex, byte padding)
    Creates a Base32 / Base32 Hex codec used for decoding and encoding.
    Base32(int lineLength, byte[] lineSeparator, boolean useHex, byte padding, CodecPolicy decodingPolicy)
    Creates a Base32 / Base32 Hex codec used for decoding and encoding.
  • Method Summary

    Modifier and Type
    Method
    Description
    (package private) void
    decode(byte[] input, int inPos, int inAvail, BaseNCodec.Context context)
    Decodes all of the provided data, starting at inPos, for inAvail bytes.
    (package private) void
    encode(byte[] input, int inPos, int inAvail, BaseNCodec.Context context)
    Encodes all of the provided data, starting at inPos, for inAvail bytes.
    boolean
    isInAlphabet(byte octet)
    Returns whether or not the octet is in the Base32 alphabet.
    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 base 32 values.
    private void
    Validates whether decoding allows final trailing characters that cannot be created during encoding.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • 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:
    • BYTES_PER_ENCODED_BLOCK

      private static final int BYTES_PER_ENCODED_BLOCK
      See Also:
    • BYTES_PER_UNENCODED_BLOCK

      private static final int BYTES_PER_UNENCODED_BLOCK
      See Also:
    • 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.
    • ENCODE_TABLE

      private static final byte[] ENCODE_TABLE
      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.
    • 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.
    • HEX_ENCODE_TABLE

      private static final byte[] HEX_ENCODE_TABLE
      This array is a lookup table that translates 5-bit positive integer index values into their "Base32 Hex Alphabet" equivalents as specified in Table 4 of RFC 4648.
    • MASK_5BITS

      private static final int MASK_5BITS
      Mask used to extract 5 bits, used when encoding Base32 bytes
      See Also:
    • MASK_4BITS

      private static final long MASK_4BITS
      Mask used to extract 4 bits, used when decoding final trailing character.
      See Also:
    • MASK_3BITS

      private static final long MASK_3BITS
      Mask used to extract 3 bits, used when decoding final trailing character.
      See Also:
    • MASK_2BITS

      private static final long MASK_2BITS
      Mask used to extract 2 bits, used when decoding final trailing character.
      See Also:
    • MASK_1BITS

      private static final long MASK_1BITS
      Mask used to extract 1 bits, used when decoding final trailing character.
      See Also:
    • decodeSize

      private final int decodeSize
      Convenience variable to help us determine when our buffer is going to run out of room and needs resizing. decodeSize = {@link #BYTES_PER_ENCODED_BLOCK} - 1 + lineSeparator.length;
    • decodeTable

      private final byte[] decodeTable
      Decode table to use.
    • 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;
    • encodeTable

      private final byte[] encodeTable
      Encode table to use.
    • lineSeparator

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

    • Base32

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

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

    • Base32

      public Base32(boolean useHex)
      Creates a Base32 codec used for decoding and encoding.

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

      Parameters:
      useHex - if true then use Base32 Hex alphabet
    • Base32

      public Base32(boolean useHex, byte padding)
      Creates a Base32 codec used for decoding and encoding.

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

      Parameters:
      useHex - if true then use Base32 Hex alphabet
      padding - byte used as padding byte.
    • Base32

      public Base32(byte pad)
      Creates 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

      public Base32(int lineLength)
      Creates 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

      public Base32(int lineLength, byte[] lineSeparator)
      Creates 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:
      IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters.
    • Base32

      public Base32(int lineLength, byte[] lineSeparator, boolean useHex)
      Creates 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 - if true, then use Base32 Hex alphabet, otherwise use Base32 alphabet
      Throws:
      IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters. Or the lineLength > 0 and lineSeparator is null.
    • Base32

      public Base32(int lineLength, byte[] lineSeparator, boolean useHex, byte padding)
      Creates 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 - if true, then use Base32 Hex alphabet, otherwise use Base32 alphabet
      padding - byte used as padding byte.
      Throws:
      IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters. Or the lineLength > 0 and lineSeparator is null.
    • Base32

      public Base32(int lineLength, byte[] lineSeparator, boolean useHex, byte padding, CodecPolicy decodingPolicy)
      Creates 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 - if true, then use Base32 Hex alphabet, otherwise use Base32 alphabet
      padding - byte used as padding byte.
      decodingPolicy - The decoding policy.
      Throws:
      IllegalArgumentException - Thrown when the lineSeparator contains Base32 characters. Or the lineLength > 0 and lineSeparator is null.
      Since:
      1.15
  • Method Details

    • 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 (e.g. 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
    • 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 base 32 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:
      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:
      IllegalArgumentException - if strict decoding is enabled