{Алгоритм 128-битного шифрования (TEA)}
unit ucrypt;
interface
type
TEAKey = array[0..3] of cardinal;
//Use 64-bit aligned data size (8,16...) or else some data will be left unencrypted!
procedure TEA_Encode(Input, Output: pointer; size: integer; key: TEAKey);
procedure TEA_Decode(Input, Output: pointer; size: integer; key: TEAKey);
implementation
type
TEAData = array[0..1] of cardinal;
PTEAKey = ^TEAKey;
PTEAData = ^TEAData;
procedure TEA_Cipher(v: PTEAData; var w: PTEAData; k: PTEAKey);
var
y, z, sum, delta, n: Cardinal;
begin
y := (v)[0];
z := (v)[1];
sum := 0;
delta := $9E3779B9;
n := 32;
while (n > 0) do
begin
inc(y, (z shl 4 xor z shr 5) + z xor sum + (k)[sum and 3]);
inc(sum, delta);
inc(z, (y shl 4 xor y shr 5) + y xor sum + (k)[sum shr 11 and 3]);
dec(n);
end;
(w)[0] := y;
(w)[1] := z;
end;
procedure TEA_DeCipher(v: PTEAData; var w: PTEAData; k: PTEAKey);
var
y, z, sum, delta, n: Cardinal;
begin
y := v[0];
z := v[1];
sum := $0C6EF3720;
delta := $9E3779B9;
n := 32;
while (n > 0) do
begin
dec(z, (y shl 4 xor y shr 5) + y xor sum + k[sum shr 11 and 3]);
dec(sum, delta);
dec(y, (z shl 4 xor z shr 5) + z xor sum + k[sum and 3]);
dec(n);
end;
w[0] := y;
w[1] := z;
end;
procedure TEA_EnDec(encode: boolean; Input, Output: pointer; size: integer; key:
TEAKey);
var
DataIn, DataOut: TEAData;
DOut: PTEAData;
i, sz: integer;
begin
DOut := @DataOut;
sz := (size shr 3) shl 3;
i := 0;
repeat
DataIn[0] := Cardinal((pointer(Cardinal(Input) + Cardinal(i)))^);
DataIn[1] := Cardinal((pointer(Cardinal(Input) + Cardinal(i + 4)))^);
if encode then
TEA_Cipher(@DataIn, DOut, @key)
else
TEA_DECipher(@DataIn, DOut, @key);
Cardinal(pointer(Cardinal(Output) + Cardinal(i))^) := DataOut[0];
Cardinal(pointer(Cardinal(Output) + Cardinal(i + 4))^) := DataOut[1];
inc(i, 8);
until i >= sz;
end;
procedure TEA_Encode(Input, Output: pointer; size: integer; key: TEAKey);
begin
TEA_EnDec(true, Input, Output, size, key);
end;
procedure TEA_Decode(Input, Output: pointer; size: integer; key: TEAKey);
begin
TEA_EnDec(false, Input, Output, size, key);
end;
end.
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