Base64 кодирование
Материал из DRKB
type
TAByte = array [0..maxInt-1] of Byte;
TPAByte = ^TAByte;
function Encode(data: string): string; overload;
const
b64: array [0..63] of char = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
var
ic, len: Integer;
pi, po: TPAByte;
c1: DWord;
begin
len := Length(data);
if len > 0 then
begin
SetLength(Result, ((len + 2) div 3) * 4);
pi := Pointer(data);
po := Pointer(Result);
for ic := 1 to len div 3 do
begin
c1 := pi^[0] shl 16 + pi^[1] shl 8 + pi^[2];
po^[0] := Byte(b64[(c1 shr 18) and $3f]);
po^[1] := Byte(b64[(c1 shr 12) and $3f]);
po^[2] := Byte(b64[(c1 shr 6) and $3f]);
po^[3] := Byte(b64[(c1 ) and $3f]);
Inc(DWord(po), 4);
Inc(DWord(pi), 3);
end;
case len mod 3 of
1:
begin
c1 := pi^[0] shl 16;
po^[0] := Byte(b64[(c1 shr 18) and $3f]);
po^[1] := Byte(b64[(c1 shr 12) and $3f]);
po^[2] := Byte('=');
po^[3] := Byte('=');
end;
2:
begin
c1 := pi^[0] shl 16 + pi^[1] shl 8;
po^[0] := byte(b64[(c1 shr 18) and $3f]);
po^[1] := byte(b64[(c1 shr 12) and $3f]);
po^[2] := byte(b64[(c1 shr 6) and $3f]);
po^[3] := byte('=');
end;
end;
end
else
Result := '';
end;
function Decode(data: string): string; overload;
var
i1, i2, len: Integer;
pi, po: TPAByte;
ch1: Char;
c1: DWord;
begin
len := Length(data);
if (len > 0) and (len mod 4 = 0) then
begin
len := len shr 2;
SetLength(Result, len * 3);
pi := Pointer(data);
po := Pointer(Result);
for i1 := 1 to len do
begin
c1 := 0;
i2 := 0;
while true do
begin
ch1 := char(pi^[i2]);
case ch1 of
'A'..'Z' : c1 := c1 or (dword(ch1) - byte('A') );
'a'..'z' : c1 := c1 or (dword(ch1) - byte('a') + 26);
'0'..'9' : c1 := c1 or (dword(ch1) - byte('0') + 52);
'+' : c1 := c1 or 62;
'/' : c1 := c1 or 63;
else
begin
if i2 = 3 then
begin
po^[0] := c1 shr 16;
po^[1] := byte(c1 shr 8);
SetLength(result, Length(result) - 1);
end
else
begin
po^[0] := c1 shr 10;
SetLength(result, Length(result) - 2);
end;
exit;
end;
end;
if i2 = 3 then
break;
Inc(i2);
c1 := c1 shl 6;
end;
po^[0] := c1 shr 16;
po^[1] := Byte(c1 shr 8);
po^[2] := Byte(c1);
Inc(DWord(pi), 4);
Inc(DWord(po), 3);
end;
end
else
Result := '';
end;
// Example
var
a, b: string;
begin
a := 'aaa';
b := Encode(a);
ShowMessage(b);
a := Decode(b);
ShowMessage(a);
end;
Author: P.O.D.
ID: 04022
const
Codes64 = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/';
function Encode64(S: string): string;
var
i: Integer;
a: Integer;
x: Integer;
b: Integer;
begin
Result := '';
a := 0;
b := 0;
for i := 1 to Length(s) do
begin
x := Ord(s[i]);
b := b * 256 + x;
a := a + 8;
while a >= 6 do
begin
a := a - 6;
x := b div (1 shl a);
b := b mod (1 shl a);
Result := Result + Codes64[x + 1];
end;
end;
if a > 0 then
begin
x := b shl (6 - a);
Result := Result + Codes64[x + 1];
end;
end;
const
Codes64 = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/';
function Decode64(S: string): string;
var
i: Integer;
a: Integer;
x: Integer;
b: Integer;
begin
Result := '';
a := 0;
b := 0;
for i := 1 to Length(s) do
begin
x := Pos(s[i], codes64) - 1;
if x >= 0 then
begin
b := b * 64 + x;
a := a + 6;
if a >= 8 then
begin
a := a - 8;
x := b shr a;
b := b mod (1 shl a);
x := x mod 256;
Result := Result + chr(x);
end;
end
else
Exit;
end;
end;
Source: http://www.swissdelphicenter.ch/en/tipsindex.php
ID: 04023
{ 64-битное декодирование файлов }
{ Arne de Bruijn }
uses dos;
var
Base64: array[43..122] of Byte;
T: text;
Chars: set of Char;
S: string;
K, I, J: Word;
Buf: Pointer;
DShift: Integer;
F: file;
B, B1: Byte;
Decode: array[0..63] of Byte;
Shift2: Byte;
Size, W: Word;
begin
FillChar(Base64, SizeOf(Base64), 255);
J := 0;
for I := 65 to 90 do
begin
Base64[I] := J;
Inc(J);
end;
for I := 97 to 122 do
begin
Base64[I] := J;
Inc(J);
end;
for I := 48 to 57 do
begin
Base64[I] := J;
Inc(J);
end;
Base64[43] := J;
Inc(J);
Base64[47] := J;
Inc(J);
if ParamCount = 0 then
begin
WriteLn('UNBASE64 <mime-файл> [<выходной файл>]');
Halt(1);
end;
S := ParamStr(1);
Assign(T, S);
GetMem(Buf, 32768);
SetTextBuf(T, Buf^, 32768);
{$I-}
Reset(T);
{$I+}
if IOResult <> 0 then
begin
WriteLn('Ошибка считывания ', S);
Halt(1);
end;
if ParamCount >= 2 then
S := ParamStr(2)
else
begin
Write('Расположение:');
ReadLn(S);
end;
Assign(F, S);
{$I-}
Rewrite(F, 1);
{$I+}
if IOResult <> 0 then
begin
WriteLn('Ошибка создания ', S);
Halt(1);
end;
while not eof(T) do
begin
ReadLn(T, S);
if (S <> '') and (pos(' ', S) = 0) and (S[1] >= #43) and (S[1] <= #122) and
(Base64[byte(S[1])] <> 255) then
begin
FillChar(Decode, SizeOf(Decode), 0);
DShift := 0;
J := 0;
Shift2 := 1;
Size := 255;
B := 0;
for I := 1 to Length(S) do
begin
case S[I] of
#43..#122: B1 := Base64[Ord(S[I])];
else
B1 := 255;
end;
if B1 = 255 then
if S[I] = '=' then
begin
B1 := 0;
if Size = 255 then
Size := J;
end
else
WriteLn('Ошибка символа:', S[I], ' (', Ord(S[I]), ')');
if DShift and 7 = 0 then
begin
Decode[J] := byte(B1 shl 2);
DShift := 2;
end
else
begin
Decode[J] := Decode[J] or Hi(word(B1) shl (DShift + 2));
Decode[J + 1] := Lo(word(B1) shl (DShift + 2));
Inc(J);
Inc(DShift, 2);
end;
end;
if Size = 255 then
Size := J;
BlockWrite(F, Decode, Size);
end;
end;
Close(F);
Close(T);
end.
Source: http://delphiworld.narod.ru/
ID: 04024