E-mail security and its implementation

In this study, e-mail communication, e-mail protocols and security weaknesses of e-mail usage are examined and a secure e-mail application, GÜ-Posta, is prepared for elimination of these weaknesses. Tools and techniques used in the developed application are summarized and the necessary basic information is given to make the subject more understandable. In GÜ-Posta application, plain message text is encrypted by a cipher. Later on, the key used for encryption is encrypted by RSA algorithm (with using recipient public key) and constituted e-mail is sent. When the receiver gets the e-mail, first of all, he decrypts the encrypted key with using RSA algorithm (with using his private key). Retrieved key is used for decryption of the cipher text. In this flexible application, by the user?s preference, message can be encrypted with symmetric encryption algorithms such as DES, 3DES, RC2 or AES. Furthermore, basic elements of security such as confidentiality, integrity, authentication and non-repudiation are ensured.