CN

CISCO/CRC.py

@@ -0,0 +1,79 @@
+
+# Returns XOR of 'a' and 'b' 
+# (both of same length) 
+def xor(a, b): 
+
+    # initialize result 
+    result = [] 
+
+    # Traverse all bits, if bits are 
+    # same, then XOR is 0, else 1 
+    for i in range(1, len(b)): 
+        if a[i] == b[i]: 
+            result.append('0') 
+        else: 
+            result.append('1') 
+
+    return ''.join(result) 
+
+
+# Performs Modulo-2 division 
+def mod2div(divident, divisor): 
+
+    # Number of bits to be XORed at a time. 
+    pick = len(divisor) 
+
+    # Slicing the divident to appropriate 
+    # length for particular step 
+    tmp = divident[0 : pick] 
+
+    while pick < len(divident): 
+
+        if tmp[0] == '1': 
+
+            # replace the divident by the result 
+            # of XOR and pull 1 bit down 
+            tmp = xor(divisor, tmp) + divident[pick] 
+
+        else:   # If leftmost bit is '0' 
+            # If the leftmost bit of the dividend (or the 
+            # part used in each step) is 0, the step cannot 
+            # use the regular divisor; we need to use an 
+            # all-0s divisor. 
+            tmp = xor('0'*pick, tmp) + divident[pick] 
+
+        # increment pick to move further 
+        pick += 1
+
+    # For the last n bits, we have to carry it out 
+    # normally as increased value of pick will cause 
+    # Index Out of Bounds. 
+    if tmp[0] == '1': 
+        tmp = xor(divisor, tmp) 
+    else: 
+        tmp = xor('0'*pick, tmp) 
+
+    checkword = tmp 
+    return checkword 
+
+# Function used at the sender side to encode 
+# data by appending remainder of modular division 
+# at the end of data. 
+def encodeData(data, key): 
+
+    l_key = len(key) 
+
+    # Appends n-1 zeroes at end of data 
+    appended_data = data + '0'*(l_key-1) 
+    remainder = mod2div(appended_data, key) 
+
+    # Append remainder in the original data 
+    codeword = data + remainder 
+    print("Remainder : ", remainder) 
+    print("Encoded Data (Data + Remainder) : ", 
+          codeword) 
+
+# Driver code 
+data = "10110010"
+key = "101"
+encodeData(data, key)

CISCO/Socket Programming/client.py

@@ -0,0 +1,9 @@
+import socket
+
+c = socket.socket()
+
+c.connect(('localhost',9999))
+name  = input("Enter your Name:")
+c.send(bytes(name,'utf-8'))
+
+print(c.recv(1024).decode())

CISCO/Socket Programming/server.py

@@ -0,0 +1,17 @@
+import socket
+
+s = socket.socket()
+print('Socket Created')
+
+s.bind(('localhost', 9999))
+
+s.listen(3)
+print('Waiting for the connection')
+
+while True:
+    c , addr = s.accept()
+
+    name = c.recv(1024).decode()
+    print('Connected with : ', addr , name)
+    c.send(bytes('Thankyou','utf-8'))
+    c.close()