Limitations of Securing Email With PGP

Limitations of Securing Email With PGP

PGP, (pretty good privacy) technology has been used to secure email communications since the early ‘90s.  Available both as freeware and commercially, PGP is the most widely used privacy-ensuring tool by both individuals and corporations.


The PGP design has not changed much since it was first introduced over twenty years ago, requiring each PGP user to have a publicly known encryption key and a private key known only to that user. Messages are encoded using a recipient’s public key, and then decoded using the recipient’s private key. This method, although highly, secure can have several limitations due to its design.


Here are 10 challenges that limit the effectiveness of PGP technology when deployed at enterprises:


1. PGP keys maintenance can be an administrative nightmare – each public and private key has its own expiration date that needs to be maintained.  In the event there is a technical failure resulting in a lost key, all the data that was encrypted with that key is lost forever. To maintain enterprise grade keys management, organizations are required to deploy a keys backup system requiring IT time and resources.


2. Organizations cannot secure large files using PGP – in most cases, email messages with file attachments that are larger than 10MB may double in size to 20MB after PGP encryption, exceeding the maximum allowed message size by the enterprise email gateway or the centralized PGP server.


3. Enterprises can share emails securely only with other organizations that use PGP –  if the recipient isn’t using PGP and does not have a public key, an encrypted message can’t be sent, therefore ad-hoc users cannot receive secure emails


4. No email receipt confirmation with PGP – the sender of a PGP based encrypted email does not receive a confirmation from the recipient that the email was successfully delivered and decrypted.


5. Cannot scan incoming PGP email with  anti-virus – in order for a message to be decoded it must go directly to the recipient without the email or the attachment being scanned by an anti-virus. To overcome this threat, organizations are required to deploy a decryption gateway server, which results in an additional costs and IT staff efforts.


6. Sensitive data stored in the DMZ – enterprises that choose to deploy a centralized decryption gateway server often deploy the server at the DMZ where emails and the attachments are decrypted before being sent to a data scanner tool. This creates an opportunity for attackers to gain access to sensitive data that is stored insecurely in the DMZ and is a significant blind spot in the organization’s data security.


7. Limits access to additional security tools – regardless of whether the PGP deployment is utilizing a centralized decryption gateway server, it cannot be integrated into a secure business workflow that makes use of additional tools such as DLP that can process/manipulate the emails and their attachments before sending them out of the organization.


8. Uncontrolled Access to email after delivery – the sender of a PGP encrypted email cannot set an expiration date for the message and its attachments, or limit the number of email views and limit the number of attachments downloads. This means that an organization’s sensitive data can be viewed insecurely by additional recipients in an uncontrolled manner.


9. Cost of maintaining client software –  cause by the fact that in most PGP based email implementations, the enterprise chooses to install a client for each one of its email users. Even if the enterprise deploys a centralized gateway server there are additional IT costs.


10. Maintenance costs of PGP based encrypted emails are high –  these costs include the cost of dedicated hardware, real estate, software licensing, service, support and user training.


By integrating a secure mail solution with a file synchronization and sharing solution, organizations can eliminate the need for complicated key maintenance and additional IT costs while benefiting from additional security features.


Once sent, the encrypted email and the attachments are stored in the virtual safe of the sending organization.  The recipient receives an email that contains only a link to the stored email at the sender’s organization, plus a one-time password. Emails can be secure after delivery including the ability to limit making the email view-only, limiting the number of attachments downloads and setting an expiry date for the email.


There is no need for systems to manage private and public keys, the sensitive data does not reside in the DMZ, and additional security measures such as DLP and data scanning and work uninterrupted.  As a result, the organizations’ sensitive data is more secure with lower maintenance and operations costs than comparable PGP solutions.

Ronen Kenig


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