encryption.java

package DiffieHellman;

public class encryption 
{
  /**
    *The list of substitution keys.
    */
  private static final String[] SUBSTITUTION_KEYS = 
  {
      "U;0XeSMLqn'V>)42zY|_fPTiJ=r Cj:phF/5Qgy63H%!-ZOkl#E8@`dRvtGxB[9?Ac]\"oIW{}<Nw^D(u$1*K+,am.sb7&",
      "<r$;8xkq|%2OP5Jey(?oW@:uRcjEaQ-vmU`^A'\"[B)fG!zh9bg4#}1iwF.VL,Z60_]NtDl=p/&>3XKd7MI*+ THnS{sYC",
      "8^NMg:v=wDzQs?9xiIjYEB{,!$de/Ty_G+m@U&t\"]rlA1*ChW)bL5ZXu 7pKH`[0R|<%n;fac>3(6POF#Sk}4V.o-q'2J",
      "n4YGp$uB<K`?}PH:Le0sW{SoO =)('jbw|^%c#A8ixZ2rM.56D]3vfR&1zy!\"/QqJTlkF;V_N9[*gCE,7>UItahdm@+-X",
      "LnF@Ax.kdE%/HZzYq`2BeN$|4p8}6lG0: JQU5Kw]VbP(mO;W='I>R*vaX<o-7y!T3\"h)i+gu1_st?[9{CMf#j,D^cSr&",
      "LtSAEHo]823iTOXf:-B@VZa&# */qd,6(;9gejPIm%xW!kM4?1FN^UR)5G| _pvzblu`c7yC.DY}'wJ[0=$h<+r>Qs{Kn\"",
      "flTWg(19Yp0sQqKybaEOXkF+L=Zd/B3HcAP<'}Mwe!-x,;)oCD5GrV.jz]|hu#:N_*{`mi\" 87RU%v&S[$2>?I6^4Jnt@",
      "w/h+JR63[b7zNuaUYG(^\"pKTcd VAeD>Ii%'$oHEMn@rCxv0l9|B;m-L#t!,_5f<sW2`4:=q]*g{j)ky.&8S}?1OXFQZP",
      "hI9Vx.OWEN*Qn<g8mY)'1zu{&adR!4:j-Fvl>L6\"0ofcCy_?i`Z[Se#bD/t%M5w3Pk,}^;pTK+XJ2( @qU]GH$7s|ABr=",
      "wkrF+Z;odYi`\"W/T,CJpt.BD{Oc]1me'}<0s(f-z&nu#AU?q)R>[QgVjvL@HaG2lby_$4N!=97hM6SE*%X| ^K:85xIP3"
    };
  
  /**
    *The list of transposition keys. 
    */
  private static final int[][] TRANSPOSITION_KEYS = 
  {
      new int[] {4, 5, 1, 2, 0, 3},
      new int[] {0, 5, 9, 6, 3, 4, 1, 7, 2, 8},
      new int[] {2, 3, 4, 7, 0, 6, 5, 1},
      new int[] {3, 1, 0, 2},
      new int[] {6, 2, 1, 0, 4, 3, 5},
      new int[] {8, 2, 6, 5, 7, 4, 3, 1, 0},
      new int[] {1, 2, 3, 6, 5, 0, 4},
      new int[] {4, 5, 2, 1, 0, 3},
      new int[] {8, 2, 3, 7, 9, 1, 0, 6, 4, 5},
      new int[] {3, 4, 2, 1, 0}
  };

  private final SubstitutionScheme substitutionScheme;
  private final TranspositionScheme transpositionScheme;
  
  /**
    *Initializes the substitution and transposition schemes.
    */
  public encryption(int privateKey) 
  {
    int keyIndex = (privateKey % SUBSTITUTION_KEYS.length);
    this.substitutionScheme = 
    new SubstitutionScheme(SUBSTITUTION_KEYS[keyIndex]);
    this.transpositionScheme = 
    new TranspositionScheme(TRANSPOSITION_KEYS[keyIndex]);
  }
  
  /**
    *Encrypts the text through substitution and then transposition.
    */
  public String encrypt(String plaintext) 
  {
    String substitutedText = substitutionScheme.encrypt(plaintext);
    return transpositionScheme.encrypt(substitutedText);
  }

  /**
    *Decrypts the text through transposition and then substitution.
    */
  public String decrypt(String ciphertext) 
  {
    String decryptedTransposition = transpositionScheme.decrypt(ciphertext);
    return substitutionScheme.decrypt(decryptedTransposition);
  }
 }