Base64加解密

const

  cBase64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

function Base64Encode(mSource: AnsiString; mAddLine: Boolean = True): AnsiString;

var

  I, J: Integer;

  S: string;

begin

  Result := '';

  J := 0;

  for I := 0 to Length(mSource) div 3 - 1 do begin

    S := Copy(mSource, I * 3 + 1, 3);

    Result := Result + cBase64[Ord(S[1]) shr 2 + 1];

    Result := Result + cBase64[((Ord(S[1]) and $03) shl 4) + (Ord(S[2]) shr 4) + 1];

    Result := Result + cBase64[((Ord(S[2]) and $0F) shl 2) + (Ord(S[3]) shr 6) + 1];

    Result := Result + cBase64[Ord(S[3]) and $3F + 1];

    if mAddLine then begin

      Inc(J, 4);

      if J >= 76 then begin

        Result := Result + #13#10;

        J := 0;

      end;

    end;

  end;

  I := Length(mSource) div 3;

  S := Copy(mSource, I * 3 + 1, 3);

  case Length(S) of

    1: begin

        Result := Result + cBase64[Ord(S[1]) shr 2 + 1];

        Result := Result + cBase64[(Ord(S[1]) and $03) shl 4 + 1];

        Result := Result + cBase64[65];

        Result := Result + cBase64[65];

      end;

    2: begin

        Result := Result + cBase64[Ord(S[1]) shr 2 + 1];

        Result := Result + cBase64[((Ord(S[1]) and $03) shl 4) + (Ord(S[2]) shr 4) + 1];

        Result := Result + cBase64[(Ord(S[2]) and $0F) shl 2 + 1];

        Result := Result + cBase64[65];

      end;

  end;

end;

function Base64Decode(mCode: AnsiString): AnsiString;

var

  I, L: Integer;

  S: string;

begin

  Result := '';

  L := Length(mCode);

  I := 1;

  while I <= L do begin

    if Pos(mCode[I], cBase64) > 0 then begin

      S := Copy(mCode, I, 4);

      if (Length(S) = 4) then begin

        Result := Result + Chr((Pos(S[1], cBase64) - 1) shl 2 +

          (Pos(S[2], cBase64) - 1) shr 4);

        if S[3] <> cBase64[65] then begin

          Result := Result + Chr(((Pos(S[2], cBase64) - 1) and $0F) shl 4 +

            (Pos(S[3], cBase64) - 1) shr 2);

          if S[4] <> cBase64[65] then

            Result := Result + Chr(((Pos(S[3], cBase64) - 1) and $03) shl 6 +

              (Pos(S[4], cBase64) - 1));

        end;

      end;

      Inc(I, 4);

    end else Inc(I);

  end;

end;