Completely Working now

playfair.py

@@ -1,15 +1,19 @@
-
 def matrix(key):
 	matrix=[]
+
 	for e in key.upper():
+		# we ignore the letter "J" and convert all occurances of "J" in the key to "I"
+		if e == "J":
+			e = "I"
+
 		if e not in matrix:
 			matrix.append(e)
 	alphabet="ABCDEFGHIKLMNOPQRSTUVWXYZ"
-	
+
 	for e in alphabet:
 		if e not in matrix:
-			matrix.append(e)	
-	
+			matrix.append(e)
+
 	#initialize a new list. Is there any elegant way to do that?
 	matrix_group=[]
 	for e in range(5):
@@ -29,21 +33,23 @@ def message_to_digraphs(message_original):
 	for e in message_original:
 		message.append(e)
 
-	#Delet space
+	#Delete space
 	for unused in range(len(message)):
 		if " " in message:
 			message.remove(" ")
 
+	# Use "X" as a filler letter
 	#If both letters are the same, add an "X" after the first letter.
 	i=0
 	for e in range(len(message)/2):
 		if message[i]==message[i+1]:
 			message.insert(i+1,'X')
 		i=i+2
 
-	#If it is odd digit, add an "X" at the end
+	# Use "Z" as a padding letters
+	#If it is odd digit, add an "Z" at the end
 	if len(message)%2==1:
-		message.append("X")
+		message.append("Z")
 	#Grouping
 	i=0
 	new=[]
@@ -62,20 +68,22 @@ def find_position(key_matrix,letter):
 
 	return x,y
 
-def encrypt(message):
+def encrypt(message, key):
 	message=message_to_digraphs(message)
 	key_matrix=matrix(key)
 	cipher=[]
 	for e in message:
-		p1,q1=find_position(key_matrix,e[0])
-		p2,q2=find_position(key_matrix,e[1])
+
+		# There was an error here as the lowercase letters were checked in the key_matrix containing uppercase letters
+		p1,q1=find_position(key_matrix,e[0].upper())
+		p2,q2=find_position(key_matrix,e[1].upper())
 		if p1==p2:
 			if q1==4:
 				q1=-1
 			if q2==4:
 				q2=-1
 			cipher.append(key_matrix[p1][q1+1])
-			cipher.append(key_matrix[p1][q2+1])		
+			cipher.append(key_matrix[p1][q2+1])
 		elif q1==q2:
 			if p1==4:
 				p1=-1;
@@ -97,20 +105,20 @@ def cipher_to_digraphs(cipher):
 	return new
 
 
-def decrypt(cipher):	
+def decrypt(cipher):
 	cipher=cipher_to_digraphs(cipher)
 	key_matrix=matrix(key)
 	plaintext=[]
 	for e in cipher:
-		p1,q1=find_position(key_matrix,e[0])
-		p2,q2=find_position(key_matrix,e[1])
+		p1,q1=find_position(key_matrix,e[0].upper())
+		p2,q2=find_position(key_matrix,e[1].upper())
 		if p1==p2:
 			if q1==4:
 				q1=-1
 			if q2==4:
 				q2=-1
 			plaintext.append(key_matrix[p1][q1-1])
-			plaintext.append(key_matrix[p1][q2-1])		
+			plaintext.append(key_matrix[p1][q2-1])
 		elif q1==q2:
 			if p1==4:
 				p1=-1;
@@ -125,7 +133,7 @@ def decrypt(cipher):
 	for unused in range(len(plaintext)):
 		if "X" in plaintext:
 			plaintext.remove("X")
-	
+
 	output=""
 	for e in plaintext:
 		output+=e
@@ -141,17 +149,21 @@ def decrypt(cipher):
 
 
 print "Playfair Cipher"
-order=input("Choose :\n1,Encrypting \n2,Decrypting\n")
+order=input("Choose :\n1.Encryption \n2.Decryption\n")
 if order==1:
 	key=raw_input("Please input the key : ")
 	message=raw_input("Please input the message : ")
 	print "Encrypting: \n"+"Message: "+message
 	print "Break the message into digraphs: "
 	print message_to_digraphs(message)
+
+	# print the matrix in a bettter way
 	print "Matrix: "
-	print matrix(key) 
-	print "Cipher: " 
-	print encrypt(message)
+	for element in matrix(key):
+		print element
+
+	print "Cipher: "
+	print encrypt(message, key)
 elif order==2:
 	key=raw_input("Please input the key : ")
 	cipher=raw_input("Please input the cipher text: ")
@@ -161,5 +173,3 @@ def decrypt(cipher):
 	print decrypt(cipher)
 else:
 	print "Error"
-
-