The project:CryptographyCeasar with our own alphabeth Exercise: Store in a variable named "Alphabet" a string containing all printable symbols.with(StringTools):[seq(convert([i],bytes),i=1..127)];Implode([seq(convert([i],bytes),i=1..127)]);Select( IsPrintable , Implode([seq(convert([i],bytes),i=1..127)]));Alphabet:=cat("\134t\134n", Select( IsPrintable , Implode([seq(convert([i],bytes),i=1..127)])));Exercise: 1. Design a procedure that takes a string of characters as input and replaces each character with the number corresponding to that character in Alphabet.2. Repeat 1. with the condition that the first character of the Alphabet should get the number 0.StringToList0:=proc(plaintext)
global Alphabet;
local i;
[seq( SearchText(plaintext[i],Alphabet),i=1..length(plaintext))];
end proc:
listN:=StringToList0("I can never make a good example");StringToList:=proc(plaintext)
global Alphabet;
local i;
[seq( -1+ SearchText(plaintext[i],Alphabet) ,i=1..length(plaintext))];
end proc:listN:=StringToList("This is the new test");Exercise: 1. Design a procedure that takes as input list of integers and replaces each entry of the list with character in that position position in Alphabet. 2. Repeat 1. with the condition that the first character of the Alphabet should get the number 0.ListToString:=proc(listnum)
global Alphabet;
Implode([seq(Alphabet[listnum[i]+1],i=1..nops(listnum))]);
end proc:ListToString(listN);Exercise: Using the two procedures above, create a new implementation of Ceaser method using the alphabet stored in "Alphabet". How would you decode an encoded message?Caesar:=proc(plaintext, shift)
local aux;
aux:=StringToList(plaintext);
aux:=map(x->modp(x+shift, length(Alphabet)), aux);
ListToString(aux);
end proc:Caesar("Now we are implementing Caesar",1);The Vignere cipherExercise: Modify the Ceasar cipher in the following way: Shift the first letter by 1, the second by 7 and the third by 3, the fourt by 1, the fifth by 7, the sixth by 3 adn so on.babyVignere:=proc(plaintext)
local aux,i;
aux:=StringToList(plaintext);
for i from 1 to length(plaintext) do
if(modp(i,3)=1) then aux[i]:=modp(aux[i]+1,length(Alphabet));
else if (modp(i,3)=2) then aux[i]:=modp(aux[i]+3,length(Alphabet));
else aux[i]:= modp(aux[i]+7,length(Alphabet));
fi; fi;
od;
return ListToString(aux);
end proc:babyVignere("New test");Exercise: Modify the Ceasar cipher in the following way: The input should be the plaintext and a list of positive integers.
Shift the first letter by the first number on the list, the second by the second number on the list and so on. This implementation will only work if your list of numbers is longer than the plaintex. How can you modify this if the list is shorter than your plaintext?NOT FINISHED . We'll continue Thursday.Vignere2:=proc(plaintext,key)
local aux,i,lengthKey;
lengthKey:=nops(key);
aux:=StringToList(plaintext);
aux[4]:=modp( aux[4]+key[mopd(4,3)] ,length(Alphabet));
return ListToString(aux);
end proc:babyVignere("New test");Exercise: Modify the Ceasar cipher in the following way: The input should be the plaintext and a string of symbols of the Alphabet.
Shift the i-th letter by the position of the i-th symbol of the string in the Alphabeth. This implementation will only work if your string is longer than the plaintex. How can you modify this if the string is shorter than your plaintext?LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYlLUkjbW9HRiQ2LVEhRicvJSxtYXRodmFyaWFudEdRJ25vcm1hbEYnLyUmZmVuY2VHUSZmYWxzZUYnLyUqc2VwYXJhdG9yR0Y0LyUpc3RyZXRjaHlHRjQvJSpzeW1tZXRyaWNHRjQvJShsYXJnZW9wR0Y0LyUubW92YWJsZWxpbWl0c0dGNC8lJ2FjY2VudEdGNC8lJ2xzcGFjZUdRLDAuMjc3Nzc3OGVtRicvJSdyc3BhY2VHRkMvJStleGVjdXRhYmxlR0Y0Ri8=Affine EncodingPublic Key CryptographyEXERCISE: Find greater common divisor of 24472 and 1540 using the Euclidean algorithm