Vigenère cipher: Difference between revisions
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}</syntaxhighlight>
The output is the same.
=={{header|Delphi}}==
{{works with|Delphi|6.0}}
{{libheader|SysUtils,StdCtrls}}
<syntaxhighlight lang="Delphi">
function UpperAlphaOnly(S: string): string;
{Remove all }
var I: integer;
begin
Result:='';
S:=UpperCase(S);
for I:=1 to Length(S) do
if S[I] in ['A'..'Z'] then Result:=Result+S[I];
end;
function VigenereEncrypt(Text, Key: string): string;
{Encrypt Text using specified key}
var KInx,TInx,I: integer;
var TC: byte;
begin
Result:='';
{Force Text and Key upper case}
Text:=UpperAlphaOnly(Text);
Key:=UpperAlphaOnly(Key);
{Point to first Key-character}
KInx:=1;
for I:=1 to Length(Text) do
begin
{Offset Text-char by key-char amount}
TC:=byte(Text[I])-byte('A')+Byte(Key[KInx]);
{if it is shifted past "Z", wrap back around past "A"}
if TC>Byte('Z') then TC:=byte('@')+(TC-Byte('Z'));
{Store in output string}
Result:=Result+Char(TC);
{Point to next Key-char}
Inc(Kinx);
{If index post end of key, start over}
if KInx>Length(Key) then KInx:=1;
end;
end;
function VigenereDecrypt(Text, Key: string): string;
{Encrypt Text using specified key}
var KInx,TInx,I: integer;
var TC: byte;
begin
Result:='';
{For Key and text uppercase}
Text:=UpperAlphaOnly(Text);
Key:=UpperAlphaOnly(Key);
KInx:=1;
for I:=1 to Length(Text) do
begin
{subtrack key-char from text-char}
TC:=byte(Text[I])-Byte(Key[Kinx])+Byte('A');
{if result below "A" wrap back around to "Z"}
if TC<Byte('A') then TC:=(byte('Z')-((Byte('A')-TC)))+1;
{store in result}
Result:=Result+Char(TC);
{Point to next key char}
Inc(Kinx);
{Past the end, start over}
if KInx>Length(Key) then KInx:=1;
end;
end;
const TestKey = 'VIGENERECIPHER';
const TestStr = 'Beware the Jabberwock, my son! The jaws that bite, the claws that catch!';
procedure VigenereCipher(Memo: TMemo);
var S: string;
begin
{Show plain text}
Memo.Lines.Add(TestStr);
S:=VigenereEncrypt(TestStr, TestKey);
{Show encrypted text}
Memo.Lines.Add(S);
S:=VigenereDecrypt(S, TestKey);
{Show decrypted text}
Memo.Lines.Add(S);
end;
</syntaxhighlight>
{{out}}
<pre>
Beware the Jabberwock, my son! The jaws that bite, the claws that catch!
WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY
BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH
Elapsed Time: 4.549 ms.
</pre>
=={{header|EasyLang}}==
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