Implement Monoalphabetic Cipher Encryption And Decryption In Python

On receiving the ciphertext, the receiver who also knows the secret shift, positions his sliding ruler underneath the ciphertext alphabet and slides it to RIGHT by the agreed shift number, 3 in this case. The result of this process is depicted in the following illustration for an agreed shift of three positions. The plaintext letter is then encrypted to the ciphertext letter on the sliding ruler underneath. In order to encrypt a plaintext letter, the sender positions the sliding ruler underneath the first set of plaintext letters and slides it to LEFT by the number of positions of the secret shift. This number which is between 0 and 25 becomes the key of encryption. This cryptosystem is generally referred to as the Shift Cipher. It is a simplest form of substitution cipher scheme. Active Oldest Votes.It is a mono-alphabetic cipher wherein each letter of the plaintext is substituted by another letter to form the ciphertext. Not really related to your problem, but you should think about replacing the 26 if s with something more elegant. You only echo the file in the while loop: You read a character in and then print it with putchar. That it isn't encrypting shouldn't be a surprise. What does 'file is not encrypted' mean IOW, what results are you getting? When you run this in a debugger or add debugging output what do you see? What I mean is its not encrypting. Viewed 4k times.ДЄlaska Alaska 11 1 1 silver badge 4 4 bronze badges. I've not implemented any controls on characters format uppercase, alphanumeric only, ecc Learn more. Now, you could speed up execution of this program by encrypting all of buffer before writing it back out to fp instead of encrypting and writing one character at a time, but you have the general idea now. Now, since you are replacing each single character with a single other character, this is easy enough to accomplish when overwriting the same file. You are doing nothing to write the output back to the file.

What you have with your encrypt function is more of a scrambling cipher.ДЄn actual shift cipher, with the key 6, for example, and the English alphabet, would look like this. Your encrypt function is not really a shift cipher. Then once you're done, you can rename the written file to replace the input if you want to. You should open a second file for writing, and write the resulting characters there.

All you do is print using putchar the encrypted character, there's no file writing code. The file doesn't change because your program does nothing that can change the contents of the file. I'm not sure, however, what exactly I'm missing. However, when I run the program, the text in the file is not encrypted.

I'm creating a substitution cipher in c, reading characters from a text file and encrypting them. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. The dark mode beta is finally here.Д¬hange your preferences any time. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Implement Monoalphabetic Cipher Encryption And Decryption In Python