 function DecrypTText(Intext: string): string;
var
  Buffer: array[0..8191] of byte;
  Hash: TDCP_sha1;
  HashDigest, HashRead: array[0..31] of byte;
  Decrypt: TDCP_blockcipher;
  // IDEA:TDCP_IDEA;
  Read: integer;
  tm, tx: tStringStream;
begin
  result := '';
  FillChar(HashDigest, Sizeof(HashDigest), $FF);
  // fill the digest with $FF as the actual digest may not fill the entire digest
  Hash := TDCP_sha1.Create(Application);
  Hash.Init; // hash the passphrase to get the key
  Hash.UpdateStr(HashPhrase);
  Hash.Final(HashDigest);
  Hash.Free;
  // IDEA:=TDCP_IDEA.create(Application);
  Decrypt := TDCP_blockcipher(Mainform.IDEA);
  // get the component from the combo box
  if (Sizeof(HashDigest) * 8) > Decrypt.MaxKeySize then
    Decrypt.Init(HashDigest, Decrypt.MaxKeySize, nil)
      // make sure the key isn't too big
  else
    Decrypt.Init(HashDigest, Sizeof(HashDigest) * 8, nil);
  // initialize the cipher with the digest, IV= nil to generate one automatically (note: size in bits ie. sizeof(x)*8)
  Decrypt.EncryptCBC(HashDigest, HashDigest, Sizeof(HashDigest));
  // encrypt the hash to use as confirmation
  Decrypt.Reset;

  intext := uuencode(intext, false);

  tx := tstringStream.create(intext);
  tm := tstringStream.create('');
  tx.seek(0, soFromBeginning);
  tx.read(HashRead, sizeof(hashread));
  (* if not CompareMem(@HashRead,@HashDigest,Sizeof(HashRead)) then
   begin
     Decrypt.Burn;
     MessageDlg('Incorrect passphrase',mtInformation,[mbOK],0);
     tx.free;
     tm.free;
     Exit;
   end;   *)
  tm.seek(0, soFromBeginning);
  repeat
    read := tx.read(buffer, sizeof(buffer));
    Decrypt.DecryptCBC(Buffer, Buffer, Read);
    // read from the source decrypt and write out the result
    tm.Write(buffer, read);
  until Read <> Sizeof(Buffer);
  Decrypt.Burn;
  // IDEA.free;
  tx.free;
  result := tm.datastring;
  tm.free;

end;

created 2 years ago

Pascal online compiler

Write, Run & Share Pascal code online using OneCompiler’s Pascal online compiler for free. It’s a straightforward, accessible way to learn and experiment with Pascal programming right from your browser. OneCompiler supports modern Pascal syntax and provides a ready-to-use editor for immediate execution.

About Pascal

Pascal is a procedural programming language developed in the 1970s by Niklaus Wirth. It was designed to encourage good programming practices and structured programming. Pascal is widely used in teaching computer science fundamentals and has influenced many modern languages.

Sample Code

The following is a simple Pascal program that prints a greeting:

program HelloWorld;
begin
  writeln('Hello, OneCompiler!');
end.

Taking inputs (stdin)

OneCompiler’s Pascal editor supports stdin through the I/O tab. Here’s an example that reads a user's name and prints a greeting:

program GreetUser;
var
  name: string;
begin
  readln(name);
  writeln('Hello, ', name, '!');
end.

Syntax Basics

Variables

var
  age: integer;
  name: string;
  score: real;
  flag: boolean;

Data Types

Type	Description
integer	Whole numbers
real	Floating-point numbers
char	Single character
string	Sequence of characters
boolean	True or False

Conditionals

if score >= 50 then
  writeln('Pass')
else
  writeln('Fail');

Loops

For loop

for i := 1 to 5 do
  writeln(i);

While loop

i := 1;
while i <= 5 do
begin
  writeln(i);
  i := i + 1;
end;

Repeat-Until loop

i := 1;
repeat
  writeln(i);
  i := i + 1;
until i > 5;

Procedures and Functions

procedure SayHello;
begin
  writeln('Hello!');
end;

function Add(a, b: integer): integer;
begin
  Add := a + b;
end;

This guide provides a quick reference to Pascal programming syntax and features. Start coding in Pascal using OneCompiler’s Pascal online compiler today!