hcrypto.engines
Class SubstitutionEngine

java.lang.Object
  |
  +--hcrypto.cipher.CipherEngine
        |
        +--hcrypto.cipher.BlockCipher
              |
              +--hcrypto.engines.SubstitutionEngine

public class SubstitutionEngine

extends BlockCipher

This class implements a keyword-based Substitution cipher algorithm for any range of alphabets, including az, AZ, azAZ, azAZ09, printable characters, all ASCII, and any of the Unicode character sets. A plaintext alphabet is retrieved from the SubstitutionKey class and stored in a character array. A cipher alphabet is created by inserting the characters from the keyword into the first elements of the array, followed by all remaining characters in the particular alphabet.

Encryption involves replacing a plaintext character from a given message with a character from the cipher alphabet with the same index. Decrypting works in the reverse order.

      plainAlphabet = [a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,......];
      keyword = calm;
      cipherAlphabet = [c,a,l,m,b,d,e,f,g,h,i,j,k,n,o,p,......];
      
      engineEncrypt("cab") == "lca"
      engineDecrypt("lca") == "cab"
 

See also:

SubstitutionKey
Alphabet

Fields inherited from class hcrypto.cipher.BlockCipher

alphabet, blocksize, cipherAlphabet

Fields inherited from class hcrypto.cipher.CipherEngine

alphabetRangeOptions

Constructor Summary

SubstitutionEngine()
Creates a SubstitutionEngine and sets the alphabetRangeOptions instance variable to "111111", which translates to all six alphabet options.

Method Summary

java.lang.String	engineDecode(java.lang.String s) Returns an encoded String for the specified String.
java.lang.String	engineEncode(java.lang.String s) Returns an encoded String for the specified String.
protected void	engineInit(HistoricalKey hKey) Initializes the SubstitutionEngine with the specified hKey.

Methods inherited from class hcrypto.cipher.BlockCipher

decodeShift, encodeShift, engineDecrypt, engineDecryptFile, engineDecryptFile, engineEncrypt, engineEncryptFile, engineEncryptFile

Methods inherited from class hcrypto.cipher.CipherEngine

getAlphabetRangeOptions

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SubstitutionEngine

public SubstitutionEngine()

Creates a SubstitutionEngine and sets the alphabetRangeOptions instance variable to "111111", which translates to all six alphabet options.

Method Detail

engineInit

protected void engineInit(HistoricalKey hKey)
                   throws java.lang.Exception

Initializes the SubstitutionEngine with the specified hKey.

Overrides:

engineInit in class BlockCipher

Parameters:

hKey - a SubstitutionKey.

engineEncode

public java.lang.String engineEncode(java.lang.String s)
                              throws java.lang.Exception

Returns an encoded String for the specified String. Characters which are not part of the chosen alphabet set are ignored.

Overrides:

engineEncode in class BlockCipher

Parameters:

s - the String to be encrypted

engineDecode

public java.lang.String engineDecode(java.lang.String s)
                              throws java.lang.Exception

Returns an encoded String for the specified String. Characters which are not part of the chosen alphabet set are ignored.

Overrides:

engineDecode in class BlockCipher

Parameters:

s - the String to be decrypted