Railfence Cipher implementation in cipher

shivansh2310 · web-flow · commit dcbc0ea14a96 · 2020-10-22T00:29:23.000+05:30
diff --git a/algorithms/cryptography/railfence_cipher.py b/algorithms/cryptography/railfence_cipher.py
@@ -0,0 +1,78 @@
+def railencrypt(st,k):
+    c = 0
+    x = 0
+    m =[[0] * (len(st)) for i in range(k)]
+    for r in range(len(st)):
+        m[c][r] = st[r]
+        if x == 0:
+            if c == (k-1):
+                x = 1
+                c -= 1
+            else:
+                c += 1
+        else:
+            if c == 0:
+                x = 0
+                c += 1
+            else:    
+                c -= 1
+           
+    result = [] 
+    for i in range(k): 
+        for j in range(len(st)): 
+            if m[i][j] != 0: 
+                    result.append(m[i][j]) 
+    print("CipherText:","" . join(result))       
+ 
+def raildecrypt(st,k):
+    c , x = 0 , 0
+    m =[[0] * (len(st)) for i in range(k)]
+    for r in range(len(st)):
+        m[c][r] = 1
+        if x == 0:
+            if c == (k-1):
+                x = 1
+                c -= 1
+            else:
+                c += 1
+        else:
+            if c == 0:
+                x = 0
+                c += 1
+            else:    
+                c -= 1
+    result = []
+    c , x = 0 , 0
+    for i in range(k): 
+        for j in range(len(st)): 
+            if m[i][j] == 1:
+                m[i][j] = st[x]
+                x += 1
+    for r in range(len(st)):
+        if m[c][r] != 0:
+            result.append(m[c][r])
+        if x == 0:
+            if c == (k-1):
+                x = 1
+                c -= 1
+            else:
+                c += 1
+        else:
+            if c == 0:
+                x = 0
+                c += 1
+            else:    
+                c -= 1
+    print("PlainText:","" . join(result))
+
+if __name__ == "__main__": 
+    string = input("Enter the Message:")
+    string = string.upper()
+    key = int(input("Enter the Key:"))
+    n = int(input("1.Encryption\n2.Decryption\nInput Your choice:"))
+    if(n == 1):
+        railencrypt(string,key)
+    elif(n == 2):
+        raildecrypt(string,key)
+    else:
+        print("Error")
