www.pudn.com > woool12.rar > EncryptUnit.pas

unit EncryptUnit; 
 
interface 
uses 
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
  Dialogs; 
type 
  TBase64 = class(TObject) 
  private 
    FOStream: TStream; 
    FIStream: TStream; 
  public 
    { 输入流 } 
    property IStream: TStream read FIStream write FIStream; 
    { 输出流 } 
    property OStream: TStream read FOStream write FOStream; 
    { 编码 } 
    function Encode(Str: string): string; 
    { 解码 } 
    function Decode(Str: string): string; 
  end; 
 
implementation 
 
const 
  SBase64           : string = 
    '23456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz~#%&*+-'; 
  UnBase64          : array[0..255] of Byte = 
    (128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //, //0-15 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //  //16-31 
    128, 128, 128, 58, 128, 59, 60, 128, 128, 128, 61, 62, 128, 63, 128, 128, 
    //32-47 
    128, 128, 0, 1, 2, 3, 4, 5, 6, 7, 128, 128, 128, 128, 128, 128, //48-63 
    128, 8, 9, 10, 11, 12, 13, 14, 15, 128, 16, 17, 18, 19, 20, 128, //64-79 
    21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 128, 128, 128, 128, 128, //80-95 
    128, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 128, 43, 44, 45, //96-111 
    46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 128, 128, 128, 57, 128, //112-127 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //128-143 
 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //144-159 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //160-175 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //176-191 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //192-207 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //208-223 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128,                                //224-239 
    128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 
    128);                               //240-255 
 
  { TBase64 } 
 
function TBase64.Decode(Str: string): string; 
var 
  j, k, len, Position: Integer; 
  B                 : Byte; 
  W, Tmp            : Byte;             //用于阅读流的临时变量 
begin 
  Result := ''; 
  if (Str <> '') then 
  begin 
    { 初始化} 
    B := 0; 
    j := 0; 
    k := 2; 
    len := Length(Str); 
    Tmp := Ord(Str[1]); 
    Position := 1; 
    while (Position <= len) and (Char(Tmp) <> '.') do 
    begin 
      if j = 0 then 
      begin 
        B := UnBase64[Tmp]; 
        k := 2; 
      end 
      else 
      begin 
        W := UnBase64[Tmp] or ((B shl k) and $C0); 
        Result := Result + Chr(W); 
        Inc(k, 2); 
      end; 
      Inc(j); 
      j := j and 3; 
      Inc(Position); 
      Tmp := Ord(Str[Position]); 
    end; 
  end; 
end; 
 
function TBase64.Encode(Str: string): string; 
var 
  SBuffer           : array[1..4] of Byte; 
  j, k, len, Position: Integer; 
  B                 : Byte; 
  Tmp               : Byte;             {### 用于阅读流的临时变量 ###} 
begin 
  Result := ''; 
  if (Str <> '') then 
  begin 
    { 初始化 } 
    len := Length(Str); 
    Tmp := Ord(Str[1]); 
    Position := 1; 
    B := 0; 
    j := 2; 
    k := 2; 
    while (Position <= len) do 
    begin 
 
      begin 
        B := B or ((Tmp and $C0) shr k); 
        Inc(k, 2); 
        SBuffer[j] := Byte(SBase64[(Tmp and $3F) + 1]); 
        Inc(j); 
        if j > 4 then 
        begin 
          SBuffer[1] := Byte(SBase64[B + 1]); 
          B := 0; 
          j := 2; 
          k := 2; 
          Result := Result + Chr(SBuffer[1]); 
        end; 
      end; 
    end; 
 
    { 平整数据到 SBuffer } 
    if j <> 2 then 
    begin 
      SBuffer[j] := Ord('.'); 
      SBuffer[1] := Byte(SBase64[B + 1]); 
      for k := 1 to j do 
        Result := Result + Chr(SBuffer[k]); 
    end 
    else 
    begin 
      SBuffer[1] := Ord('.'); 
      for k := 1 to j do 
        Result := Result + Chr(SBuffer[k]); 
    end; 
 
  end; 
end; 
 
end.