unit Base64Unit;

unit Base64Unit;

//Download by http://www.codefans.net

interface

uses

  Classes, SysUtils;

  function Base64Encryption(const Input:String):String;

  function Base64Decryption(const Input:String):String;

implementation

const

  BASE64Table : array[0..63] of Char = ( #65,  #66,  #67,  #68,  #69,

         #70,  #71,  #72,  #73,  #74,  #75,  #76,  #77,  #78,  #79,

         #80,  #81,  #82,  #83,  #84,  #85,  #86,  #87,  #88,  #89,

         #90,  #97,  #98,  #99, #100, #101, #102, #103, #104, #105,

        #106, #107, #108, #109, #110, #111, #112, #113, #114, #115,

        #116, #117, #118, #119, #120, #121, #122,  #48,  #49,  #50,

         #51,  #52,  #53,  #54,  #55,  #56,  #57,  #43,  #47);

const

  BASE64DeTable : array[43..122] of Byte = ($3E, $7F, $7F, $7F, $3F, $34,

      $35, $36, $37, $38, $39, $3A, $3B, $3C, $3D, $7F, $7F, $7F, $7F,

      $7F, $7F, $7F, $00, $01, $02, $03, $04, $05, $06, $07, $08, $09,

      $0A, $0B, $0C, $0D, $0E, $0F, $10, $11, $12, $13, $14, $15, $16,

      $17, $18, $19, $7F, $7F, $7F, $7F, $7F, $7F, $1A, $1B, $1C, $1D,

      $1E, $1F, $20, $21, $22, $23, $24, $25, $26, $27, $28, $29, $2A,

      $2B, $2C, $2D, $2E, $2F, $30, $31, $32, $33);

//BASE64算法流加密

procedure EncodeStream(InStream, OutStream : TStream);

var

  I, O, Count : Integer;

  InBuf  : array[1..45] of Byte;

  OutBuf : array[0..62] of Char;

  Temp : Byte;

begin

  FillChar(OutBuf, Sizeof(OutBuf), #0);

  repeat

    Count := InStream.Read(InBuf, SizeOf(InBuf));

    if Count = 0 then Break;

    I := 1;

    O := 0;

    while I <= (Count-2) do begin

      { 编码第一个字节 }

      Temp := (InBuf[I] shr 2);

      OutBuf[O] := Char(BASE64Table[Temp and $3F]);

      { 编码第二个字节 }

      Temp := (InBuf[I] shl 4) or (InBuf[I+1] shr 4);

      OutBuf[O+1] := Char(BASE64Table[Temp and $3F]);

      { 编码第三个字节 }

      Temp := (InBuf[I+1] shl 2) or (InBuf[I+2] shr 6);

      OutBuf[O+2] := Char(BASE64Table[Temp and $3F]);

      { 编码第四个字节 }

      Temp := (InBuf[I+2] and $3F);

      OutBuf[O+3] := Char(BASE64Table[Temp]);

      Inc(I, 3);

      Inc(O, 4);

    end;

    if (I <= Count) then begin

      Temp := (InBuf[I] shr 2);

      OutBuf[O] := Char(BASE64Table[Temp and $3F]);

      { 一个奇数字节 }

      if I = Count then begin

        Temp := (InBuf[I] shl 4) and $30;

        OutBuf[O+1] := Char(BASE64Table[Temp and $3F]);

        OutBuf[O+2] := '=';

      { 两个基数字节 }

      end else begin

        Temp := ((InBuf[I] shl 4) and $30) or ((InBuf[I+1] shr 4) and $0F);

        OutBuf[O+1] := Char(BASE64Table[Temp and $3F]);

        Temp := (InBuf[I+1] shl 2) and $3C;

        OutBuf[O+2] := Char(BASE64Table[Temp and $3F]);

      end;

      { 增加= }

      OutBuf[O+3] := '=';

      Inc(O, 4);

    end;

    { 把编码好的块写到流中 }

    OutStream.Write(OutBuf, O);

  until Count < SizeOf(InBuf);

end;

//BASE64算法流解密

procedure DecodeStream(InStream, OutStream : TStream);

var

  I, O, Count, c1, c2, c3 : Byte;

  InBuf  : array[0..87] of Byte;

  OutBuf : array[0..65] of Byte;

begin

  repeat

    O := 0;

    I := 0;

    Count := InStream.Read(InBuf, SizeOf(InBuf));

    if (Count = 0) then

      Break;

    { 解密的数据输入到流中 }

    while I < Count do begin

      if (InBuf[I] < 43) or (InBuf[I] > 122) or

         (InBuf[I+1] < 43) or (InBuf[I+1] > 122) or

         (InBuf[I+2] < 43) or (InBuf[I+2] > 122) or

         (InBuf[I+3] < 43) or (InBuf[I+3] > 122) then

        raise Exception.Create('Invalid Base64 Character');

      c1 := BASE64DeTable[InBuf[I]];

      c2 := BASE64DeTable[InBuf[I+1]];

      c3 := BASE64DeTable[InBuf[I+2]];

      OutBuf[O] := ((c1 shl 2) or (c2 shr 4));

      Inc(O);

      if Char(InBuf[I+2]) <> '=' then begin

        OutBuf[O] := ((c2 shl 4) or (c3 shr 2));

        Inc(O);

        if Char(InBuf[I+3]) <> '=' then begin

          OutBuf[O] := ((c3 shl 6) or BASE64DeTable[InBuf[I+3]]);

          Inc(O);

        end;

      end;

      Inc(I, 4);

    end;

    OutStream.Write(OutBuf, O);

  until Count < SizeOf(InBuf);

end;

//BASE64算法字符串加密

function Base64Encryption(const Input:String):String;

var

  InStream  : TMemoryStream;

  OutStream : TMemoryStream;

begin

  InStream := TMemoryStream.Create;

  OutStream := TMemoryStream.Create;

  InStream.Write(Input[1], Length(Input));

  InStream.Position := 0;

  EncodeStream(InStream, OutStream);

  OutStream.Position := 0;

  SetLength(Result, OutStream.Size);

  OutStream.Read(Result[1], OutStream.Size);

  InStream.Free;

  OutStream.Free;

end;

//BASE64算法字符串解密

function Base64Decryption(const Input:String):String;

var

  InStream  : TMemoryStream;

  OutStream : TMemoryStream;

begin

  InStream := TMemoryStream.Create;

  OutStream := TMemoryStream.Create;

  InStream.Write(Input[1], Length(Input));

  InStream.Position := 0;

  DecodeStream(InStream, OutStream);

  OutStream.Position := 0;

  SetLength(Result, OutStream.Size);

  OutStream.Read(Result[1], OutStream.Size);

  InStream.Free;

  OutStream.Free;

end;

end.