which the e-mail system is accessed, and

point of failure, when it is fail, we need

authentication of legitimate users.

a backup.

Implementation issue that is complicated

to overcome is the native security

policies of the different e-mail servers

a processing overhead emphasized that

encrypting a e-mail does not allow a third

party to see the content.

Ghafoor et al. [2]

Enhance e-mail system using certificates, smart

The proxy server represents a single point

Cards and crypto objects with high degree of

of failure, when it is fail we need a backup.

Security for professional users.

J. Jang et al. [16]

Trusting both parties according to their TPM


key then make a triple encryption transferred



Al-taee et al. [1]

Ensuring the confidentiality of the email

Exponential relationship between the time

message plaintext using improved encryption

used for the encryption/ decryption and

and decryption algorithm and ensuring the

the plaintext size

authentication between the email sender and

receiver using biometric features.

Shukla et al. [9]

Provides e-mails with confidentiality by using

The system can be initiated before

Symmetric block ciphering algorithm. The

inserting the E-Token

integrity is provided using the SHA-1 and RSA.

It uses three authentication techniques:

password, Biometric authentication and E-Token,

to validate the e-mail account and the user.

Non-Repudiation achieved using the

bi-directional digital signature.