Package org.cryptacular.codec

Class AbstractBaseNDecoder

java.lang.Object
org.cryptacular.codec.AbstractBaseNDecoder
All Implemented Interfaces:
Decoder
Direct Known Subclasses:
Base32Decoder, Base64Decoder
public abstract class AbstractBaseNDecoder extends Object implements Decoder
Base decoder class for encoding schemes described in RFC 3548.
Author:
Middleware Services

  • Constructor Details

    • AbstractBaseNDecoder

      public AbstractBaseNDecoder(byte[] decodingTable)
      Creates a new instance with given parameters.
      Parameters:
      decodingTable - Byte array indexed by characters in the character set encoding.

    • AbstractBaseNDecoder

      public AbstractBaseNDecoder(byte[] decodingTable, boolean paddedInput)
      Creates a new instance with given parameters.
      Parameters:
      decodingTable - Byte array indexed by characters in the character set encoding.
      paddedInput - True to enable support for padded input, false otherwise.

  • Method Details

    • isPaddedInput

      public boolean isPaddedInput()
      Returns:
      True if padded input is accepted (default), false otherwise.

    • decode

      public void decode(CharBuffer input, ByteBuffer output) throws EncodingException
      Description copied from interface: Decoder
      Decodes characters in input buffer into bytes placed in the output buffer. This method may be called multiple times, followed by Decoder.finalize(ByteBuffer). after all input bytes have been provided.
      Specified by:
      decode in interface Decoder
      Parameters:
      input - Input character buffer.
      output - Output byte buffer.
      Throws:
      EncodingException - on decoding errors.

    • finalize

      public void finalize(ByteBuffer output) throws EncodingException
      Description copied from interface: Decoder
      Performs final output decoding (e.g. padding) after all input characters have been provided.
      Specified by:
      finalize in interface Decoder
      Parameters:
      output - Output byte buffer.
      Throws:
      EncodingException - on decoding errors.

    • outputSize

      public int outputSize(int inputSize)
      Description copied from interface: Decoder
      Expected number of bytes in the output buffer for an input buffer of the given size.
      Specified by:
      outputSize in interface Decoder
      Parameters:
      inputSize - Size of input buffer in characters.
      Returns:
      Minimum byte buffer size required to store all decoded characters in input buffer.

    • getBlockLength

      protected abstract int getBlockLength()
      Returns:
      Number of bits in a block of encoded characters.

    • getBitsPerChar

      protected abstract int getBitsPerChar()
      Returns:
      Number of bits encoding a single character.

    • decodingTable

      protected static byte[] decodingTable(String alphabet, int n)
      Converts the given alphabet into a base-N decoding table.
      Parameters:
      alphabet - Decoding alphabet to use.
      n - Encoding base.
      Returns:
      Decoding table of 128 elements.