<solved>Easy encryption of text files... Code added 16052024

[Thaddy]

Interesting way of doing @Thaddy
IKR that what I now suggest would be against your code but I'll suggest to make it a class, internal work with TStream, at end or start add a fixed size hash generated from password/passkey so the class could quick abort decryption or output some other kind of data ....

I made it a advanced record, but I want to reduce (without speed loss ) the code a little.
Here's what I have now:

Code: Pascal  [Select][+][-]

1. unit cryptrandom;
2.  
3. {$mode objfpc}{$modeswitch advancedrecords}
4. {$warn 5024 off}
5. interface
6.  
7. type
8. {$if not declared(Tbytes) It may be declared in another used unit }
9.    TBytes = Array of byte;
10. {$ifend}
11.  
12.   TRandomCrypt = record
13.   strict private
14.     { Maintains state }
15.     FRandSeed:Cardinal;
16.     function IM:Cardinal;inline;
17.   public
18.     { ShortString encryption }
19.     function Crypt(const Value:ShortString; Key:Cardinal;Cycles:Cardinal = 1):ShortString;inline;
20.     { AnsiString encryption }
21.     function Crypt(const Value:AnsiString; Key:Cardinal;Cycles:Cardinal = 1):AnsiString;inline;
22.     { UTF8String encryption }
23.     function Crypt(const Value:UTF8String; Key:Cardinal;Cycles:Cardinal = 1):UTF8String;inline;
24.     { UnicodeString encryption }
25.     function Crypt(const Value:UnicodeString; Key:Cardinal;Cycles:Cardinal = 1):UnicodeString;inline;
26.     { RawByteString, preserves codepage }
27.     function Crypt(const Value:RawByteString; Key:Cardinal;Cycles:Cardinal = 1):RawByteString;
28.     { Binary encryption }
29.     function Crypt(const Value:TBytes; Key:Cardinal;Cycles:Cardinal = 1):TBytes;inline;
30.   end;
31.  
32. implementation
33.  
34.   function TRandomCrypt.IM:Cardinal;inline;
35.   begin
36.     FRandSeed := FRandSeed * 134775813  + 1;
37.     Result := FRandSeed;
38.   end;
39.  
40.   function TRandomCrypt.Crypt(const Value:ShortString; Key:Cardinal;Cycles:Cardinal = 1):ShortString;inline;
41.   var
42.     i,j:integer;
43.   begin
44.     Result :='';
45.     FRandSeed:= Key;
46.     Setlength(Result, Length(Value));
47.     For i:= 1 to Cycles do
48.       for j:= 1 to length(Value) do
49.         Result[j] := chr(Ord(Value[j]) xor (IM * Key shr 32));
50.   end;
51.  
52.   function TRandomCrypt.Crypt(const Value:AnsiString; Key:Cardinal;Cycles:Cardinal = 1):AnsiString;inline;
53.   var
54.     i,j:integer;
55.   begin
56.     Result :='';
57.     FRandSeed:= Key;
58.     Setlength(Result, Length(Value));
59.     For i:= 1 to Cycles do
60.       for j:= 1 to length(Value) do
61.         Result[j] := chr(Ord(Value[j]) xor (IM * Key shr 32));
62.   end;
63.  
64.   function TRandomCrypt.Crypt(const Value:UTF8String; Key:Cardinal;Cycles:Cardinal = 1):UTF8String;
65.   var
66.     i,j:integer;
67.   begin
68.     Result :='';
69.     FRandSeed:= Key;
70.     Setlength(Result, Length(Value));
71.     For i:= 1 to Cycles do
72.       for j:= 1 to length(Value) do
73.         Result[j] := chr(Ord(AnsiChar(Value[j])) xor (IM * Key shr 32));
74.   end;
75.  
76.   function TRandomCrypt.Crypt(const Value:UnicodeString; Key:Cardinal;Cycles:Cardinal = 1):UnicodeString;
77.   var
78.     i,j:integer;
79.   begin
80.   {$ifdef unix}
81.   {$hint Not all Nixes always play nice with UTF16, use UTF8String instead. Crypt is OK, though }
82.   {$endif}
83.     Result :='';
84.     FRandSeed:= Key;
85.     Setlength(Result, Length(Value));
86.     For i:= 1 to Cycles do
87.       for j:= 1 to length(Value) do
88.         Result[j] := chr(Ord(AnsiChar(Value[j])) xor (IM * Key shr 32));
89.   end;
90.  
91.   function TRandomCrypt.Crypt(const Value:RawByteString; Key:Cardinal;Cycles:Cardinal = 1):RawByteString;
92.   var
93.     i,j:integer;
94.   begin
95.     Setlength(Result,Length(Value));
96.     FRandSeed:= Key;
97.     Setlength(Result, Length(Value));
98.     For i:= 1 to Cycles do
99.       for j:= 1 to length(Value) do
100.         Result[j] := chr(Ord(AnsiChar(Value[j])) xor (IM * Key shr 32));
101.   end;
102.  
103.   function TRandomCrypt.Crypt(const Value:TBytes; Key:Cardinal;Cycles:Cardinal = 1):TBytes;inline;
104.   var
105.     i,j:integer;
106.   begin
107.     Setlength(Result,Length(Value));
108.     FRandSeed:= Key;
109.     Setlength(Result, Length(Value));
110.     For i:= 1 to Cycles do
111.       for j:= 0 to high(Value) do
112.         Result[j] := Value[j] xor (IM * Key shr 32);
113.   end;
114.  
115. end.

example to play with:

Code: Pascal  [Select][+][-]

1. { using a localized random based on Delphi's LCG, but you can use any PRNG }
2. {$mode objfpc}{$modeswitch advancedrecords}
3. {$codepage UTF8}// so we can use Unicode literal strings for testing}
4. uses
5.   CryptRandom;
6.  
7. var
8. { change string type as required. All encrypt good,
9.   but presentation may be confusing}
10.  a:UnicodeString;
11.  Crypt:TRandomCrypt;
12.  Key:Cardinal = 12345;
13. begin
14.  Crypt := Default(TRandomCrypt);
15.  a:='This is thè téxt to êncrypt/decrypt Ä.'; // based on nothing at all...
16.  writeln(a);
17.  writeln('Encrypting..');
18.  a:=Crypt.Crypt(a,Key, 100);
19.  writeln(a);
20.  writeln('Decrypting..');
21.  a:=Crypt.Crypt(a, Key, 100);
22.  writeln(a);
23. end.

I am pretty sure I will get comments about this code from people who do not know what they are talking about.
I am also pretty sure I get comments from the dick heads like me...(which are sane except not for other people)
Meaning, yes, there is repeating code that should be factored out. So don't comment on that.

This code works on most string types and binary data and is much better than simply xor.

If Key and cycles do not match, you will get garbage.
This one is pretty safe, but not cryptographically secure, (But close)

You can plug-in any PRNG you like based on this code (which uses Delphi's PRNG)
The random is now locallized to the record scope and can't interfear with the normal random.

[Dzandaa]

Hi,
@Sprek Skik

I use this:

Package: DCPCrypt

Code: Pascal  [Select][+][-]

1. use
2.         Classes, SysUtils, Dialogs,
3.         DCPrc6, DCPsha512, base64,
4.         zstream;  
5.  
6. // ************************
7. // ***** Crypt String *****
8. // ************************
9. function Encrypt(SInput, SKey: String): String;
10. var
11.         DecodedStream: TStringStream;
12.         EncodedStream: TStringStream;
13.         Str: String;
14.         Cipher: TDCP_rc6;
15. begin
16.         try
17.                 DecodedStream := TStringStream.Create(SInput);
18.                 EncodedStream := TStringStream.Create('');
19.  
20.                 Cipher:= TDCP_rc6.Create(nil);
21.                 Cipher.InitStr(SKey,TDCP_sha512);              // initialize the cipher with a hash of the passphrase
22.                 Cipher.EncryptStream(DecodedStream,EncodedStream,DecodedStream.Size); // encrypt the contents of the file
23.  
24.                 Str := EncodeStringBase64(EncodedStream.DataString); // Convert to Base64
25.  
26.                 Cipher.Burn;
27.                 Cipher.Free;
28.                 DecodedStream.Free;
29.                 EncodedStream.Free;
30.                 exit(Str);
31.         except
32.                         exit('');
33.         end;
34.         exit('');
35. end;
36.  
37. // **************************
38. // ***** Decrypt String *****
39. // **************************
40. function Decrypt(Sinput, SKey: String): String;
41. var
42.         DecodedStream: TStringStream;
43.         EncodedStream: TStringStream;
44.         Str: String;
45.         Cipher: TDCP_rc6;
46. begin
47.         try
48.                 EncodedStream := TStringStream.Create(DecodeStringBase64(SInput)); // Base 64 Decode the Data
49.                 DecodedStream := TStringStream.Create('');
50.  
51.                 Cipher:= TDCP_rc6.Create(nil);
52.                 Cipher.InitStr(SKey,TDCP_sha512);              // initialize the cipher with a hash of the passphrase
53.                 Cipher.DecryptStream(EncodedStream,DecodedStream,EncodedStream.Size); // decrypt the contents of the file
54.  
55.                 Str := DecodedStream.DataString;
56.                 Cipher.Burn;
57.                 Cipher.Free;
58.                 EncodedStream.Free;
59.                 DecodedStream.Free;
60.                 exit(Str)
61.         except
62.                 exit('');
63.         end;
64.         exit('');
65. end;
66.  
67. // ***************************
68. // ***** Compress String *****
69. // ***************************
70. function Compress(SInput: String): String;
71. var
72.         Compressor: TCompressionStream;
73.         strInput, strOutput: TStringStream;
74.         Str: String;
75. begin
76.  
77.         strInput := TStringStream.Create(SInput);
78.         strOutput := TStringStream.Create('');
79.  
80.         try
81.                 Compressor := TCompressionStream.Create(clDefault, strOutput);
82.  
83.                 Compressor.CopyFrom(strInput, strInput.Size);
84.                 Compressor.Free;
85.                 Str := strOutput.DataString;
86.  
87.                 strOutput.Free;
88.                 strInput.Free;
89.  
90.                 exit(Str);
91.         except
92.                 exit('');
93.         end;
94.         exit('');
95. end;
96.  
97. // *****************************
98. // ***** Decompress String *****
99. // *****************************
100. function Decompress(Sinput: String): String;
101. var
102.         Decompressor: TDecompressionStream;
103.         strInput, strOutput: TStringStream;
104.         Str: String;
105. begin
106.         strInput := TStringStream.Create(Sinput);
107.         strOutput := TStringStream.Create('');
108.  
109.         try
110.                 Decompressor := TDecompressionStream.Create(strInput);
111.  
112.                 strOutput.Position := 0;
113.                 strOutput.Size := 0;
114.  
115.                 strOutput.CopyFrom(Decompressor, 0);
116.                 Decompressor.Free;
117.                 Str := strOutput.DataString;
118.  
119.                 strOutput.Free;
120.                 strInput.Free;
121.  
122.                 exit(Str);
123.         except
124.                 exit('');
125.         end;
126.         exit('');
127. end;                                            
128.  

B->

[Thaddy]

That is not the issue at hand: the issue is proving random can be used to encrypt and decrypt.
To quote myself:

I am pretty sure I will get comments about this code from people who do not know what they are talking about.

I am sure your intentions are good.

[KodeZwerg]

the issue is

That nobody offered a solution for what the OP is asking for, de-/encrypt text files.
However cool the crypt logic might be, no shown method as of right now do that.
TBytes is at least a possibility to work with files when for that purpose a wrapper would be added.

[Fibonacci]

the issue is

That nobody offered a solution for what the OP is asking for, de-/encrypt text files.

Code: Pascal  [Select][+][-]

1. uses chacha20, Classes;
2.  
3. var
4.   cc: chacha20state;
5.   f: TFileStream;
6.   n: integer;
7.   buff: array[0..(1024*64)-1] of byte;
8.  
9. begin
10.   // ---- encrypt ----
11.  
12.   chacha20_init(cc, 'key', 'nonce');
13.  
14.   f := TFileStream.Create('file.txt', fmOpenReadWrite);
15.  
16.   while f.Position < f.Size do begin
17.     // read chunk
18.     n := f.Read(buff, length(buff));
19.     // encrypt or decrypt
20.     chacha20_xor(cc, @buff[0], n);
21.     // save
22.     f.Position := f.Position-n;
23.     f.Write(buff, n);
24.   end;
25.  
26.   f.Free;
27.  
28.   writeln('file encrypted, <enter> to decrypt');
29.   readln;
30.  
31.   // ---- decrypt ----
32.  
33.   chacha20_init(cc, 'key', 'nonce');
34.  
35.   f := TFileStream.Create('file.txt', fmOpenReadWrite);
36.  
37.   while f.Position < f.Size do begin
38.     // read chunk
39.     n := f.Read(buff, length(buff));
40.     // encrypt or decrypt
41.     chacha20_xor(cc, @buff[0], n);
42.     // save
43.     f.Position := f.Position-n;
44.     f.Write(buff, n);
45.   end;
46.  
47.   f.Free;
48.  
49.   writeln('file decrypted');
50.   readln;
51. end.

[Thaddy]

That is again beyond the scope .

[Sprek Skik]

Hi,
@Sprek Skik

I use this:

Package: DCPCrypt

Code: Pascal  [Select][+][-]

1. use
2.         Classes, SysUtils, Dialogs,
3.         DCPrc6, DCPsha512, base64,
4.         zstream;  
5.  
6. // ************************
7. // ***** Crypt String *****
8. // ************************
9. function Encrypt(SInput, SKey: String): String;
10. var
11.         DecodedStream: TStringStream;
12.         EncodedStream: TStringStream;
13.         Str: String;
14.         Cipher: TDCP_rc6;
15. begin
16.         try
17.                 DecodedStream := TStringStream.Create(SInput);
18.                 EncodedStream := TStringStream.Create('');
19.  
20.                 Cipher:= TDCP_rc6.Create(nil);
21.                 Cipher.InitStr(SKey,TDCP_sha512);              // initialize the cipher with a hash of the passphrase
22.                 Cipher.EncryptStream(DecodedStream,EncodedStream,DecodedStream.Size); // encrypt the contents of the file
23.  
24.                 Str := EncodeStringBase64(EncodedStream.DataString); // Convert to Base64
25.  
26.                 Cipher.Burn;
27.                 Cipher.Free;
28.                 DecodedStream.Free;
29.                 EncodedStream.Free;
30.                 exit(Str);
31.         except
32.                         exit('');
33.         end;
34.         exit('');
35. end;
36.  
37. // **************************
38. // ***** Decrypt String *****
39. // **************************
40. function Decrypt(Sinput, SKey: String): String;
41. var
42.         DecodedStream: TStringStream;
43.         EncodedStream: TStringStream;
44.         Str: String;
45.         Cipher: TDCP_rc6;
46. begin
47.         try
48.                 EncodedStream := TStringStream.Create(DecodeStringBase64(SInput)); // Base 64 Decode the Data
49.                 DecodedStream := TStringStream.Create('');
50.  
51.                 Cipher:= TDCP_rc6.Create(nil);
52.                 Cipher.InitStr(SKey,TDCP_sha512);              // initialize the cipher with a hash of the passphrase
53.                 Cipher.DecryptStream(EncodedStream,DecodedStream,EncodedStream.Size); // decrypt the contents of the file
54.  
55.                 Str := DecodedStream.DataString;
56.                 Cipher.Burn;
57.                 Cipher.Free;
58.                 EncodedStream.Free;
59.                 DecodedStream.Free;
60.                 exit(Str)
61.         except
62.                 exit('');
63.         end;
64.         exit('');
65. end;
66.  
67. // ***************************
68. // ***** Compress String *****
69. // ***************************
70. function Compress(SInput: String): String;
71. var
72.         Compressor: TCompressionStream;
73.         strInput, strOutput: TStringStream;
74.         Str: String;
75. begin
76.  
77.         strInput := TStringStream.Create(SInput);
78.         strOutput := TStringStream.Create('');
79.  
80.         try
81.                 Compressor := TCompressionStream.Create(clDefault, strOutput);
82.  
83.                 Compressor.CopyFrom(strInput, strInput.Size);
84.                 Compressor.Free;
85.                 Str := strOutput.DataString;
86.  
87.                 strOutput.Free;
88.                 strInput.Free;
89.  
90.                 exit(Str);
91.         except
92.                 exit('');
93.         end;
94.         exit('');
95. end;
96.  
97. // *****************************
98. // ***** Decompress String *****
99. // *****************************
100. function Decompress(Sinput: String): String;
101. var
102.         Decompressor: TDecompressionStream;
103.         strInput, strOutput: TStringStream;
104.         Str: String;
105. begin
106.         strInput := TStringStream.Create(Sinput);
107.         strOutput := TStringStream.Create('');
108.  
109.         try
110.                 Decompressor := TDecompressionStream.Create(strInput);
111.  
112.                 strOutput.Position := 0;
113.                 strOutput.Size := 0;
114.  
115.                 strOutput.CopyFrom(Decompressor, 0);
116.                 Decompressor.Free;
117.                 Str := strOutput.DataString;
118.  
119.                 strOutput.Free;
120.                 strInput.Free;
121.  
122.                 exit(Str);
123.         except
124.                 exit('');
125.         end;
126.         exit('');
127. end;                                            
128.  

B->

Looking at the code I don't know how to implement it to my code. See my added code in the original message.
thnx for the response

[KodeZwerg]

Looking at the code I don't know how to implement it to my code. See my added code in the original message.
thnx for the response

First your should fix the encryption part, aslong that is wrong, decrypt will always fail.
Your code:

Code: Pascal  [Select][+][-]

1.   for i:= 0 to Memo1.Lines.Count-1 do       // decrypt the contents of the memo
2.     begin
3.       if Memo1.Lines <> '' then
4.         Memo1.Lines:= Cipher.EncryptString(Memo1.Lines);
5.     end;

Fixed:

Code: Pascal  [Select][+][-]

1. Cipher.EncryptString(Memo1.Text);

I have not looked in detail but that is a main error. Hope it helps!

[Dzandaa]

Hi,
@Sprek Skik

Try This:

Code: Pascal  [Select][+][-]

1. var Str, MyKey: String;
2. ...
3.  MyKey := 'TestKey';
4. // Encrypt
5.  Str := Memo1.Text;
6.  Str := Encrypt(Compress(Str), MyKey);  
7.  Memo1.Clear;
8.  Memo1.Append(Str);
9.  
10. // Decrypt
11.  Str := Memo1.Text;
12.  Str := Decompress(Decrypt(Str, MyKey));
13.  Memo1.Clear;
14.  Memo1.Append(Str);
15.  

B->

[Thaddy]

In my examle code it would be simply:

Code: Pascal  [Select][+][-]

1.   Memo1.Iines.Text := Crypt.Crypt(Memo1.Lines.Text, Key);

To decrypt it, You call the same method.
It is also stronger encryped than e.g. RC4 or DES3. Especially if you use cycles.

Code: Pascal  [Select][+][-]

1.   Memo1.Iines.Text := Crypt.Crypt(Memo1.Lines.Text, Key,10);

This is a known property of PRNG's

[Dzandaa]

Hi,
Compress and Decompress are optional, just for add complexity to the cryptage

You can also use:

Code: Pascal  [Select][+][-]

1.  Memo1.Iines.Text := Encrypt(Memo1.Lines.Text, MyKey);
2.  Memo1.Iines.Text := Decrypt(Memo1.Lines.Text, MyKey);
3.  

B->

[Thaddy]

With my code you can use:

Code: Pascal  [Select][+][-]

1. {$macro on}{$define encode := crypt.crypt}{$define decode:= crypt.crypt}

[Sprek Skik]

Looking at the code I don't know how to implement it to my code. See my added code in the original message.
thnx for the response

First your should fix the encryption part, aslong that is wrong, decrypt will always fail.
Your code:

Code: Pascal  [Select][+][-]

1.   for i:= 0 to Memo1.Lines.Count-1 do       // decrypt the contents of the memo
2.     begin
3.       if Memo1.Lines <> '' then
4.         Memo1.Lines:= Cipher.EncryptString(Memo1.Lines);
5.     end;

Fixed:

Code: Pascal  [Select][+][-]

1. Cipher.EncryptString(Memo1.Text);

I have not looked in detail but that is a main error. Hope it helps!

Something was wrong so I will try it...... It was example code that I tried to fix, but everything is new for me.
thnx for the info

[Sprek Skik]

Looking at the code I don't know how to implement it to my code. See my added code in the original message.
thnx for the response

First your should fix the encryption part, aslong that is wrong, decrypt will always fail.
Your code:

Code: Pascal  [Select][+][-]

1.   for i:= 0 to Memo1.Lines.Count-1 do       // decrypt the contents of the memo
2.     begin
3.       if Memo1.Lines <> '' then
4.         Memo1.Lines:= Cipher.EncryptString(Memo1.Lines);
5.     end;

Fixed:

Code: Pascal  [Select][+][-]

1. Cipher.EncryptString(Memo1.Text);

I have not looked in detail but that is a main error. Hope it helps!

I have tried your code but there is no encryption at all, but also no problems ;-)

[Fibonacci]

Code: Pascal  [Select][+][-]

1. uses chacha20, base64, md5;

ChaCha20.pas here

Code: Pascal  [Select][+][-]

1. function encrypt(data, password: string): string;
2. var
3.   key: string;
4.   cc: chacha20state;
5. begin
6.   // md5 hash of password as key
7.   key := MD5Print(MD5String(password));
8.   // encrypt with ChaCha20
9.   chacha20_init(cc, key, ''{empty nonce});
10.   chacha20_xor(cc, @data[1], length(data));
11.   // return base64 encoded
12.   result := EncodeStringBase64(data);
13. end;
14.  
15. function decrypt(data, password: string): string;
16. var
17.   key: string;
18.   cc: chacha20state;
19. begin
20.   // decode base64
21.   data := DecodeStringBase64(data);
22.   // md5 hash of password as key
23.   key := MD5Print(MD5String(password));
24.   // decrypt with ChaCha20
25.   chacha20_init(cc, key, ''{empty nonce});
26.   chacha20_xor(cc, @data[1], length(data));
27.   // return decrypted
28.   result := data;
29. end;
30.  
31. procedure TForm1.Button1Click(Sender: TObject);
32. begin
33.   Memo1.Text := encrypt(Memo1.Text, 'password');
34. end;
35.  
36. procedure TForm1.Button2Click(Sender: TObject);
37. begin
38.   Memo1.Text := decrypt(Memo1.Text, 'password');
39. end;