Bacon cipher: Difference between revisions
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# Show an example plaintext message encoded and then decoded here on this page.
<br><br>
=={{header|Ada}}==
{{trans|Kotlin}}
<lang Ada>-- Bacon cipher
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
with Ada.Characters.Handling; use Ada.Characters.Handling;
with Ada.Strings.Fixed; use Ada.Strings.Fixed;
with Ada.Containers.Ordered_Maps;
procedure Main is
subtype encode_str is String (1 .. 5);
subtype lower_case is Character range 'a' .. 'z';
subtype Upper_case is Character range 'A' .. 'Z';
package Alphabet is new Ada.Containers.Ordered_Maps
(Key_Type => Character, Element_Type => encode_str);
use Alphabet;
blank : constant Character := ' ';
Bacon : Map;
function encode (Plain_Text : String; Message : String) return String is
plain_lower : String := To_Lower (Plain_Text);
temp : Unbounded_String;
msg_lower : String := To_Lower (Message);
str : encode_str;
begin
for c of plain_lower loop
if c in lower_case then
str := Bacon.Element (c);
else
str := Bacon.Element (blank);
end if;
Append (Source => temp, New_Item => str);
end loop;
declare
encoded : String := To_String (temp);
Count : Positive := encoded'First;
result : Unbounded_String;
begin
for c of msg_lower loop
exit when Count > encoded'last;
if c in lower_case then
if encoded (Count) = 'A' then
Append (Source => result, New_Item => c);
else
Append (Source => result, New_Item => To_Upper (c));
end if;
Count := Count + 1;
else
Append (Source => result, New_Item => c);
end if;
end loop;
return To_String (result);
end;
end encode;
function Index (Item : Map; Pattern : encode_str) return Character is
result : Character := ' ';
value : encode_str;
begin
for key in lower_case loop
value := Item.Element (key);
if value = Pattern then
result := key;
exit;
end if;
end loop;
return result;
end Index;
function decode (Message : String) return String is
encoded : Unbounded_String;
begin
for c of Message loop
if c in lower_case then
Append (Source => encoded, New_Item => 'A');
elsif c in Upper_case then
Append (Source => encoded, New_Item => 'B');
end if;
end loop;
declare
encoded_string : String := To_String (encoded);
idx : Positive := encoded_string'First;
Result : Unbounded_String;
c : Character;
str : encode_str;
begin
loop
str := encoded_string (idx .. idx + 4);
c := Index (Item => Bacon, Pattern => str);
Append (Source => Result, New_Item => c);
idx := idx + 5;
exit when idx + 4 > encoded_string'Last;
end loop;
return To_String (Result);
end;
end decode;
P_Text : String := "the quick brown fox jumps over the lazy dog";
P_Msg : String :=
"bacon's cipher is a method of steganography created by francis bacon. " &
"this task is to implement a program for encryption and decryption of " &
"plaintext using the simple alphabet of the baconian cipher or some " &
"other kind of representation of this alphabet (make anything signify anything). " &
"the baconian alphabet may optionally be extended to encode all lower " &
"case characters individually and/or adding a few punctuation characters " &
"such as the space.";
begin
Bacon.Insert (Key => 'a', New_Item => "AAAAA");
Bacon.Insert (Key => 'b', New_Item => "AAAAB");
Bacon.Insert (Key => 'c', New_Item => "AAABA");
Bacon.Insert (Key => 'd', New_Item => "AAABB");
Bacon.Insert (Key => 'e', New_Item => "AABAA");
Bacon.Insert (Key => 'f', New_Item => "AABAB");
Bacon.Insert (Key => 'g', New_Item => "AABBA");
Bacon.Insert (Key => 'h', New_Item => "AABBB");
Bacon.Insert (Key => 'i', New_Item => "ABAAA");
Bacon.Insert (Key => 'j', New_Item => "ABAAB");
Bacon.Insert (Key => 'k', New_Item => "ABABA");
Bacon.Insert (Key => 'l', New_Item => "ABABB");
Bacon.Insert (Key => 'm', New_Item => "ABBAA");
Bacon.Insert (Key => 'n', New_Item => "ABBAB");
Bacon.Insert (Key => 'o', New_Item => "ABBBA");
Bacon.Insert (Key => 'p', New_Item => "ABBBB");
Bacon.Insert (Key => 'q', New_Item => "BAAAA");
Bacon.Insert (Key => 'r', New_Item => "BAAAB");
Bacon.Insert (Key => 's', New_Item => "BAABA");
Bacon.Insert (Key => 't', New_Item => "BAABB");
Bacon.Insert (Key => 'u', New_Item => "BABAA");
Bacon.Insert (Key => 'v', New_Item => "BABAB");
Bacon.Insert (Key => 'w', New_Item => "BABBA");
Bacon.Insert (Key => 'x', New_Item => "BABBB");
Bacon.Insert (Key => 'y', New_Item => "BBAAA");
Bacon.Insert (Key => 'z', New_Item => "BBAAB");
Bacon.Insert (Key => blank, New_Item => "BBBAA");
declare
ciphertext : String := encode (Plain_Text => P_Text, Message => P_Msg);
begin
Put_Line ("Cipher text:");
Put_Line (ciphertext);
New_Line;
Put_Line ("Hidden text:");
Put_Line (decode (ciphertext));
end;
end Main;</lang>
{{output}}
<pre>
Cipher text:
BacON's cIPHer Is a METhoD of stEgAnogRaphy crEatEd By FRAncis baCOn. thIs TASk Is TO imPLeMENT a proGrAm FOR eNcRYPTIOn anD deCRyPtioN Of plAINTExt UsING the SIMpLe AlPhaBet Of thE BAConIan CIphER Or sOme OTHer kInD Of reprESenTATion OF This alPHaBET (makE An
Hidden text:
the quick brown fox jumps over the lazy dog
</pre>
=={{header|Agena}}==
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