Secure Communication Simulation

The project is a simulation of secure communication between two parties, hence include two applications sender and reciver. Programs use Pyhton Cryptograyphy toolkit to achive their tasks.

Sender do the following:

1. Digitally sign a message (file) using RSA PKCS1_PSS to produce a file called msg.sig.
2. Encrypt the message using AES with a 128 bit key 𝐾 to produce a file called msg.crypt.
3. Encrypt 𝐾 using RSA with the receiver's public key and save to a file called symkey.crypt.
4. "Transmit" msg.sig,msg.crypt,sym.key (No need to do anything for transmission).

Takes three command line inputs all of which are filenames:

1. Message file
2. Sender's private key file for signing.
3. Reciver's public key (for encrypting the symmetric key)

Receiver performs the following:

1. Use her private key to decrypt symkey.crypt to produce symkey.
2. Use symkey to decrypt msg.crypt to produce msg.
3. Use the sender's public key to verify that msg.sig is a valid signature for msg.

Reciever also takes three command line inputs.

Key Generation

Key for both parties are generated through openSSl (software library for applications that secure communications over computer networks).

openssl genrsa -out private.pem 2048
openssl rsa -in private.pem -out private.der -outform DER
openssl rsa -in private.pem -outform DER -pubout -out public.der
openssl rand 16 > aes.key

Run programs

send.py msg.txt send_priv.der rec_pub.der
receive.py symkey.crypt msg.crypt msg.sig