program_outline.txt

sender = 	X
receiver = 	Y


Sender and Receiver

X Y		Create RSA key pairs (privX, pubX, privY, pubY)
		Get modulus and exponent of each RSA key and save them to files
			XPrivate.key, XPublic.key, YPrivate.key, YPublic.key

X Y		Create symetric AES key and save it to a file called
			xAES.key and yAES.key


Sender:

X		Read private and public key info from files
		Generate RSA keys from info

X		Get filename of message from user

X		Read in file (called message)
		Store file in memory as a byte array

X		Calculate the SHA256 hash value of the file
		Store the hash in memory as a byte array
		Store the hash as a file named "message.dd"
		Write the hash value (in base-16) to the log file.

X		Encrypt the hash with privX, call it the digital signature
		Store the digital signature in memory as a byte array
		Store the digital signature as a file named "message.ds-msg"
		Write the digital signature (in base-16) to the log file.

X		Append the message byte array to the digital signature byte array
		Call this new array hashAndMessage

-->		Send a connection request to Y

<--		Wait for a response/confirmation from Y

-->		Send msg saying that public key is ready to be transmitted

<--		Wait for response/confirmation

-->		Send file XPublic.key to Y

<--		Get confirmation from Y

<--		Wait for message from Y saying that symetric key is ready to be sent

-->		Send response/confirmation

<--		Receive AES key file from Y

-->		Send confirmation to Y

X		Decrypt AES key using privX
		Load AES key into byte array

X		Initialze AES object using key

X		Encrypt hashAndMessage using AES object
		Write encrypted file to disk, block by block
		Save the file as "message.aescipher"

X		If mod mode is active, ask user to modify file before transmission

-->		Send message saying that encrypted file is ready to be transmitted

<--		Wait for response/confirmation

-->		Transmit encrypted file block by block to Y

<--		Wait for response from Y saying transmission accepted

<--		Wait for response from Y confirming hash

X		Close connection



Receier

Y		Set up a socket
		Listen for a connection

<--		Receive connection request form X

-->		Open a connection and send confirmation to Y

<--		Wait for a message saying public key is ready to be transmitted

Y		Create a buffered stream reader

-->		Send response/confirmation to X

<--		Receive publicX.key

-->		Send repsonse/confirmation to X

Y		Initalize RSA object with public key

Y		Encrypt yAES.key with publicX
		Represent encrypted key as byte array in memory

-->		Send message to X saying AES key ready

<--		Wait for message/confirmation

-->		Transmit encrypted AES key to Y

<--		Wait for response/confirmation from Y

...

<--		Wait for message from Y saying encrypted file ready to be transmitted

-->		Send repsonse/confirmation

<--		Receive encrypted file
		Write it to disk block by block
		Save it as ""

-->		Send repsonse/confirmation

Y		Ask user to enter name of file to be saved

Y		Read encrypted file from disk block by block
		Decrypt block using yAES object
		Extract first XX bytes and save in memory as hash
		Write remaining blocks/data to <filename>

Y		Calculate SHA256 hash value on remaining blocks/data
		Write calculated hash to log file in base-16

Y		Initialze RSA object using publicX.key

Y		Use publicX key to decrypt encrypted hash
		Write decrypted hash to disk as "message.dd"

Y		Compare calculated hash to decrypted hash and write results to log

-->		Send X a message stating if the file transfer was successful (hash values match)

Y		Close connection