des.pas

DES加密算法,是一个很著名的加密算法

procedure permutation(var inData: array of Byte); 
var 
  newData: array[0..3] of Byte; 
  i: Integer; 
begin 
  FillChar(newData, 4, 0); 
  for i := 0 to 31 do 
    if (inData[BitPM[i] shr 3] and (1 shl (7-(BitPM[i] and $07))))  < > 0 then 
      newData[i shr 3] := newData[i shr 3] or (1 shl (7-(i and $07))); 
  for i := 0 to 3 do inData[i] := newData[i]; 
end; 

function si(s,inByte: Byte): Byte; 
var 
  c: Byte; 
begin 
  c := (inByte and $20) or ((inByte and $1e) shr 1) or 
    ((inByte and $01) shl 4); 
  Result := (sBox[s][c] and $0f); 
end; 

procedure permutationChoose1(inData: array of Byte; 
  var outData: array of Byte); 
var 
  i: Integer; 
begin 
  FillChar(outData, 7, 0); 
  for i := 0 to 55 do 
    if (inData[BitPMC1[i] shr 3] and (1 shl (7-(BitPMC1[i] and $07))))  < > 0 then 
      outData[i shr 3] := outData[i shr 3] or (1 shl (7-(i and $07))); 
end; 

procedure permutationChoose2(inData: array of Byte; 
  var outData: array of Byte); 
var 
  i: Integer; 
begin 
  FillChar(outData, 6, 0); 
  for i := 0 to 47 do 
    if (inData[BitPMC2[i] shr 3] and (1 shl (7-(BitPMC2[i] and $07))))  < > 0 then 
      outData[i shr 3] := outData[i shr 3] or (1 shl (7-(i and $07))); 
end; 

procedure cycleMove(var inData: array of Byte; bitMove: Byte); 
var 
  i: Integer; 
begin 
  for i := 0 to bitMove - 1 do 
  begin 
    inData[0] := (inData[0] shl 1) or (inData[1] shr 7); 
    inData[1] := (inData[1] shl 1) or (inData[2] shr 7); 
    inData[2] := (inData[2] shl 1) or (inData[3] shr 7); 
    inData[3] := (inData[3] shl 1) or ((inData[0] and $10) shr 4); 
    inData[0] := (inData[0] and $0f); 
  end; 
end; 

procedure makeKey(inKey: array of Byte; var outKey: array of TKeyByte); 
const 
  bitDisplace: array[0..15] of Byte = 
    ( 1,1,2,2, 2,2,2,2, 1,2,2,2, 2,2,2,1 ); 
var 
  outData56: array[0..6] of Byte; 
  key28l: array[0..3] of Byte; 
  key28r: array[0..3] of Byte; 
  key56o: array[0..6] of Byte; 
  i: Integer; 
begin 
  permutationChoose1(inKey, outData56); 

  key28l[0] := outData56[0] shr 4; 
  key28l[1] := (outData56[0] shl 4) or (outData56[1] shr 4); 
  key28l[2] := (outData56[1] shl 4) or (outData56[2] shr 4); 
  key28l[3] := (outData56[2] shl 4) or (outData56[3] shr 4); 
  key28r[0] := outData56[3] and $0f; 
  key28r[1] := outData56[4]; 
  key28r[2] := outData56[5]; 
  key28r[3] := outData56[6]; 

  for i := 0 to 15 do 
  begin 
    cycleMove(key28l, bitDisplace[i]); 
    cycleMove(key28r, bitDisplace[i]); 
    key56o[0] := (key28l[0] shl 4) or (key28l[1] shr 4); 
    key56o[1] := (key28l[1] shl 4) or (key28l[2] shr 4); 
    key56o[2] := (key28l[2] shl 4) or (key28l[3] shr 4); 
    key56o[3] := (key28l[3] shl 4) or (key28r[0]); 
    key56o[4] := key28r[1]; 
    key56o[5] := key28r[2]; 
    key56o[6] := key28r[3]; 
    permutationChoose2(key56o, outKey[i]); 
  end; 
end; 

procedure encry(inData, subKey: array of Byte; 
   var outData: array of Byte); 
var 
  outBuf: array[0..5] of Byte; 
  buf: array[0..7] of Byte; 
  i: Integer; 
begin 
  expand(inData, outBuf); 
  for i := 0 to 5 do outBuf[i] := outBuf[i] xor subKey[i]; 
                                                // outBuf       xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx 
  buf[0] := outBuf[0] shr 2;                                  //xxxxxx - > 2 
  buf[1] := ((outBuf[0] and $03) shl 4) or (outBuf[1] shr 4); // 4  <- xx xxxx - > 4 
  buf[2] := ((outBuf[1] and $0f) shl 2) or (outBuf[2] shr 6); //        2  <- xxxx xx - > 6 
  buf[3] := outBuf[2] and $3f;                                //                    xxxxxx 
  buf[4] := outBuf[3] shr 2;                                  //                           xxxxxx 
  buf[5] := ((outBuf[3] and $03) shl 4) or (outBuf[4] shr 4); //                                 xx xxxx 
  buf[6] := ((outBuf[4] and $0f) shl 2) or (outBuf[5] shr 6); //                                        xxxx xx 
  buf[7] := outBuf[5] and $3f;                                //                                               xxxxxx 
  for i := 0 to 7 do buf[i] := si(i, buf[i]); 
  for i := 0 to 3 do outBuf[i] := (buf[i*2] shl 4) or buf[i*2+1]; 
  permutation(outBuf); 
  for i := 0 to 3 do outData[i] := outBuf[i]; 
end; 

procedure desData(desMode: TDesMode; 
  inData: array of Byte; var outData: array of Byte); 
// inData, outData 都为8Bytes，否则出错 
var 
  i, j: Integer; 
  temp, buf: array[0..3] of Byte; 
begin 
  for i := 0 to 7 do outData[i] := inData[i]; 
  initPermutation(outData); 
  if desMode = dmEncry then 
  begin 
    for i := 0 to 15 do 
    begin 
      for j := 0 to 3 do temp[j] := outData[j];                 //temp = Ln 
      for j := 0 to 3 do outData[j] := outData[j + 4];         //Ln+1 = Rn 
      encry(outData, subKey[i], buf);                           //Rn ==Kn== > buf 
      for j := 0 to 3 do outData[j + 4] := temp[j] xor buf[j];  //Rn+1 = Ln^buf 
    end; 

    for j := 0 to 3 do temp[j] := outData[j + 4]; 
    for j := 0 to 3 do outData[j + 4] := outData[j]; 
    for j := 0 to 3 do outData[j] := temp[j]; 
  end 
  else if desMode = dmDecry then 
  begin 
    for i := 15 downto 0 do 
    begin 
      for j := 0 to 3 do temp[j] := outData[j]; 
      for j := 0 to 3 do outData[j] := outData[j + 4]; 
      encry(outData, subKey[i], buf); 
      for j := 0 to 3 do outData[j + 4] := temp[j] xor buf[j]; 
    end; 
    for j := 0 to 3 do temp[j] := outData[j + 4]; 
    for j := 0 to 3 do outData[j + 4] := outData[j]; 
    for j := 0 to 3 do outData[j] := temp[j]; 
  end; 
  conversePermutation(outData); 
end; 

////////////////////////////////////////////////////////////// 

function EncryStr(Str, Key: String): String; 
var 
  StrByte, OutByte, KeyByte: array[0..7] of Byte; 
  StrResult: String; 
  I, J: Integer; 
begin 
  if (Length(Str)  > 0) and (Ord(Str[Length(Str)]) = 0) then 
    raise Exception.Create( 'Error: the last char is NULL char. '); 
  if Length(Key)  < 8 then 
    while Length(Key)  < 8 do Key := Key + Chr(0); 
  while Length(Str) mod 8  < > 0 do Str := Str + Chr(0); 

  for J := 0 to 7 do KeyByte[J] := Ord(Key[J + 1]); 
  makeKey(keyByte, subKey); 

  StrResult :=  ' '; 

  for I := 0 to Length(Str) div 8 - 1 do 
  begin 
    for J := 0 to 7 do 
      StrByte[J] := Ord(Str[I * 8 + J + 1]); 
    desData(dmEncry, StrByte, OutByte); 
    for J := 0 to 7 do 
      StrResult := StrResult + Chr(OutByte[J]); 
  end; 

  Result := StrResult; 
end; 

function DecryStr(Str, Key: String): String; 
var 
  StrByte, OutByte, KeyByte: array[0..7] of Byte; 
  StrResult: String; 
  I, J: Integer; 
begin 
  if Length(Key)  < 8 then 
    while Length(Key)  < 8 do Key := Key + Chr(0); 

  for J := 0 to 7 do KeyByte[J] := Ord(Key[J + 1]); 
  makeKey(keyByte, subKey); 

  StrResult :=  ' '; 

  for I := 0 to Length(Str) div 8 - 1 do 
  begin 
    for J := 0 to 7 do StrByte[J] := Ord(Str[I * 8 + J + 1]); 
    desData(dmDecry, StrByte, OutByte); 
    for J := 0 to 7 do 
      StrResult := StrResult + Chr(OutByte[J]); 
  end; 
  while (Length(StrResult)  > 0) and 
    (Ord(StrResult[Length(StrResult)]) = 0) do 
    Delete(StrResult, Length(StrResult), 1); 
  Result := StrResult; 
end; 

/////////////////////////////////////////////////////////// 

function EncryStrHex(Str, Key: String): String; 
var 
  StrResult, TempResult, Temp: String; 
  I: Integer; 
begin 
  TempResult := EncryStr(Str, Key); 
  StrResult :=  ' '; 
  for I := 0 to Length(TempResult) - 1 do 
  begin 
    Temp := Format( '%x ', [Ord(TempResult[I + 1])]); 
    if Length(Temp) = 1 then Temp :=  '0 ' + Temp; 
    StrResult := StrResult + Temp; 
  end; 
  Result := StrResult; 
end; 

function DecryStrHex(StrHex, Key: String): String; 
  function HexToInt(Hex: String): Integer; 
  var 
    I, Res: Integer; 
    ch: Char; 
  begin 
    Res := 0; 
    for I := 0 to Length(Hex) - 1 do 
    begin 
      ch := Hex[I + 1]; 
      if (ch  >=  '0 ') and (ch  <=  '9 ') then 
        Res := Res * 16 + Ord(ch) - Ord( '0 ') 
      else if (ch  >=  'A ') and (ch  <=  'F ') then 
        Res := Res * 16 + Ord(ch) - Ord( 'A ') + 10 
      else if (ch  >=  'a ') and (ch  <=  'f ') then 
        Res := Res * 16 + Ord(ch) - Ord( 'a ') + 10 
      else raise Exception.Create( 'Error: not a Hex String '); 
    end; 
    Result := Res; 
  end; 

var 
  Str, Temp: String; 
  I: Integer; 
begin 
  Str :=  ' '; 
  for I := 0 to Length(StrHex) div 2 - 1 do 
  begin 
    Temp := Copy(StrHex, I * 2 + 1, 2); 
    Str := Str + Chr(HexToInt(Temp)); 
  end; 
  Result := DecryStr(Str, Key); 
end; 

end.