Hacktober

python/checksum.py

@@ -0,0 +1,85 @@
+# checksum 
+# author : Om Rawal
+# 15/09/2020 19:31
+
+
+def BinaryToDecimal(binary):  
+
+    binary1 = binary  
+    decimal, i, n = 0, 0, 0
+    while(binary != 0):  
+        dec = binary % 10
+        decimal = decimal + dec * pow(2, i)  
+        binary = binary//10
+        i += 1
+    return (decimal)     
+
+def binaryToDec(n): 
+    return int(n,2) 
+
+print('Welcome to CheckSum')
+message=input('Enter the message to send.: ')
+print('Message entered is ',message)
+print('Generating Dataword ...')
+dataword=[] #length 7
+for i in range(len(message)):
+    if(message[i]!=' '):
+        res = ''.join(format(k, 'b') for k in bytearray(message[i], encoding ='utf-8'))
+        dataword.append(res)
+    else:
+        res = ''.join(format(k, 'b') for k in bytearray(message[i], encoding ='utf-8'))
+        res='0'+res
+        dataword.append(res)
+print('calculating checksum......')
+csum='0000000'
+for i in dataword:
+    csum= bin(int(csum,2) + int(i,2))[2:]
+dataword.append(csum)
+
+print('sending dataword......')
+print(''.join(dataword))
+flag=int(input('1. To induce error\n2. To have no error'))
+if(flag==1):
+    index=int(input('Enter Index: '))
+    ak=''.join(dataword)
+    k=list(ak)
+    # print('k',k)
+    # print('ak',ak)
+    if(k[index]=='0'):
+        k[index]='1'
+    else:
+        k[index]='0'
+    a=[]
+    i=0
+    while(i<len(k)):
+        kk=''.join(k[i:i+7])
+        a.append(kk)
+        i+=7
+    dataword=a
+
+print('receiving dataword......')
+print(''.join(dataword))
+print('checking error....')
+csum='0000000'
+for i in range(len(dataword)-1):
+    csum= bin(int(csum,2) + int(dataword[i],2))[2:]
+if(csum==dataword[len(dataword)-1]):
+    print('No Error')
+    print('Decoding message...')
+    bin_data=''.join(dataword[:len(dataword)-1])
+    print("The binary value is:", bin_data) 
+    decoded_message =' '
+    for i in range(0, len(bin_data), 7): 
+
+        temp_data = int(bin_data[i:i + 7]) 
+
+        decimal_data = BinaryToDecimal(temp_data) 
+        decoded_message = decoded_message + chr(decimal_data)  
+
+    print("The Decoded message is: ",  
+        decoded_message) 
+
+else:
+    print('Error!!!\n Requesing Retransmission.....')
+    # diff= bin(abs(int(csum,2) - int(dataword[i],2)))[2:]
+    # print(binaryToDec(diff))