Sender-Defined Security

When you send an email to a recipient, who bears the highest risk?

Usually, you. Because the information is transferred from sender to recipient, the sender likely has the highest risk. The information may be valuable to both, but the sender is the party that can be found liable for (even if inadvertently) disclosing it to others. Email is risk-asymmetric.

For example, patients may initiate communications with a health care provider using unencrypted email, according to HIPAA. This is done at the patient's risk. However, providers may have concerns when replying to the patient using unencrypted email. Providers are subject to potential liability under the HIPAA Privacy Rule [see 45 C.F.R. § 164.530(c)], including their determination whether a patient is aware of the possible risks of using unencrypted email.

Since the sender is the party at risk, the sender needs to be able to define the security conditions, for example, for confidentiality, delivery, and tracking of the message.

Let's see how certified postal mail works. The sender chooses the service and the type of envelope to protect the message. The sender also chooses the instructions
that must be followed before the envelope can be opened by the recipient. The recipient has no charge to pay for, or burden, in order to receive the envelope, and does not have to do anything before the envelope is sent. The recipient is able to verify the identity of the sender and, if so desired, refuse the envelope. The recipient can open the envelope if and only if the recipient is willing to follow the sender's instructions (e.g., providing name, address, date, signature).

The same should be available for sender-defined security modes of operation for email.

Using IBE encryption (Identity-Based Encryption, Voltage, MessageGuard) does not work because IBE requires sender key-escrow, so that the sender is always at risk that her messages can be read by someone else.

Clearly, a conventional public-key model (PKI, X.509, PGP) cannot provide this functionality either. The security model for protecting email with public-key cryptography is backwards, technically and business wise. The sender, who is the party at risk, has to trust a lock provided by the recipient (his public-key) to protect her secrets (the message).

If certified postal mail would provide message security a la PGP, PGP/MIME or S/MIME email, the sender would have to convince the recipient to pay and send in advance an envelope for the sender to use. The sender, however, would never know whether the envelope indeed prevented others from prying into its contents. Moreover, the recipient is not the business driver who needs to provide, pay for and protect the lock. The sender is the party who has the motivation to spend money to provide and protect the lock.

These are well-known and recognized standards for encryption of email. However, their security and usability problems noted above cannot be solved by improvements in usability, better pricing or user education regarding how IBE, PKI, X.509, or PGP work. It simply does not work as it should work. That's also why conventional secure email has been difficult to use. It has the wrong logic for the problem.

ZSentry is a security technology that was developed after these standards and improves upon them in both usability and security. ZSentry provides per-message encryption, authentication, message control, and auditing, protecting information in motion and at rest. ZSentry reduces the trust and control requirements in several critical areas, making it easier to attain and demonstrate a higher level of security while increasing usability.

Most importantly, ZSentry enables a secure email system that works closer to how postal mail, including courier and certified postal mail, works.

Because ZSentry mail can be delivered securely to both registered and also to unregistered users, the sender is able to define the delivery conditions that must be satisfied by the recipient before the message can be decrypted (delivered) in each case.

For example, based on what is at stake and what threats may apply, versus the usability requirements, the sender can select from the following delivery conditions:

Require Registration: (For higher security: use this option) The recipient must register before reading the message. After the recipient registers, delivery is further controlled by the Delivery option specified by you for registered users (see next items).

Require Login: (For higher security: use this option) The recipient must be registered and login before reading the message. To reduce risk, this process includes mailbox authentication, login monitoring, message expiration, and other control features.

Read Until Expiration: (For higher usability: use this option) Available for both registered and unregistered users. The recipient is allowed to decrypt the Zmail, including attachments (if any), as many times as desired until the message expires. The security of the Read Until Expiration mode is based on mailbox authentication, login monitoring, and expiration control. The sender can choose when to expire, where the sooner the better for security.

Reply to Sender: (available in all options, including without registration or login) This is a very useful choice to receive a secure reply, as the recipient has no burden to reply securely (can reply securely just with one-click).

The security of these Delivery choices is further enhanced by other choices, including for Control and Tracking, for example allowing the sender to choose a message self-destruct time and real-time audit reporting with a Return Receipt.
The Return Receipt is sent back to you with information on When, Where, How, and by Whom your message was read.

You can also compare the Return Receipt with the corresponding Send Receipt (available from the server, upon sending), closing the loop with potentially more comprehensive delivery and notary evidence than using courier or certified postal mail, with less cost and immediate delivery.

In summary, ZSentry puts the sender in the driver's seat of secure email, with more and more effective options than any other system including IBE, PKI, X.509, PGP, courier and certified postal mail.