Initial data commit

Task/Vigen-re-cipher/Delphi/vigen-re-cipher.delphi

@@ -0,0 +1,79 @@
+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;