Original URL: http://www.theregister.co.uk/2008/08/15/home_office_crypto_bureau/

Home Office reaches half-way hash in secure data handling

Encryption bureau to operate like internal post office

By John Leyden

Posted in Security, 15th August 2008 10:09 GMT

Analysis The UK Home Office has introduced procedures to handle encrypted personal data from external partners. However, guidelines on how the new Home Office Central Cryptography service will work raise concerns about possible shortcomings with the service which, while a big improvement, falls below best practice in sectors such as banking.

Procedures outlined in the guidelines follow a major Whitehall review prompted by the HMRC data loss debacle. The guidelines are a break from working practices that saw CDs with sensitive unencrypted data regularly winging their way via internal mail, sometimes to oblivion, but fall short of offering a full end-to-end service.

The Home Office Central Cryptography service (announced in June) will make use of PGP to handle data but, once received, emails will be decrypted and forwarded to their intended recipients within the government department. While the government secure intranet provides security protections, an end-to-end system would be preferable. The reader who forwarded us the documents went further, suggesting it "defeats the whole purpose" of sending data encrypted in the first place.

Files up to 6.5MB in size will go to an email address and a dedicated machine within the central cryptography bureau, while the guidelines call for files between 6.5MB and 50MB in size to be handled through an external email service (gmx.com). Files larger than 50MB are to be sent on an encrypted CD or DVD via either courier or recorded delivery.

Mid-range files are to be left on servers before they are picked up by their intended recipients. These files are too big to email internally but too small to come via recorded media so instead they will be "placed in a 'pick-up' zone on the network folder for immediate retrieval and deletion".

The system uses of symmetric-key cryptography, so both the sender and the Home Office will share the same key for a particular communication. (This is less secure than public-key cryptography where each party uses a set of two mathematically related keys to lock and unlock messages.) External parties are advised to use complex passphrases to encrypt messages and to send them under separate cover, as explained below:

The encryption must be carried out using 3rd-party pre-defined passphrase only. The sender should ensure a strong passphrase is created. The encrypted file may be created as a PGP file or a self-decrypting executable (.exe) file. The passphrase should be sent to the Bureau separately to the encrypted data (the Bureau will contact the sender for passphrase).

Jamie Cowper, director of marketing at PGP, observed that the required use of strong passphrases sent out separately from the main communication, shows the Home Office has sought expert advice (probably from the GCHQ's CESG group) in developing its plans. "You'd be surprised, but some people sent encrypted discs with the passphrase attached on a post-it note," he added.

While it would be better for the Home Office bureau to publish its own public key and apply public-key cryptography to provide end-to-end encryption the use of a centralised encryption bureau is at least workable and perhaps appropriate, according to Cowper.

"It's preferable to have end-to-end cryptography but it all depends on the nature of the information you are trying to protect and the scale of the network," he said.

Government departments aiming to improve security have focused most of their energy on rolling out laptop encryption. "Laptop activity is the immediate problem. The government is less focused on email security. We'd argue that's where the data flows but there is still a perception about ease of use of email encryption," Cowper explained.

Sending encrypted communications in the form of a self-decrypting archive means that no client is required, but also requires accepting executable files in email messages, a dangerous practice in general - especially bearing in mind that UK government departments are a prime target for targeted Trojan attacks.

However we understand that the PC that accepts the encrypted email from third parties is a standalone machine, not networked to internal Home Office IT systems or connected to the Government Secure Intranet.

"There's a balance between scanner and encryption which is why the Home Office have taken a sandbox approach. For communication with small third party organisations - who have few resources - the centralised encryption bureau is an interesting model. For secure communications with commercial bodies this may need another pass," Cowper concluded.

The Home Office explanation on how encrypted communications will be handled raises further concerns about possible impersonation.

Encrypted data from 3rd party originator to Encryption Bureau
  1. Email/CD/DVD is received by the Bureau.
  2. Bureau will contact the originator to confirm receipt and provide reference number and gain passphrase.
  3. Bureau will decrypt file.
  4. Bureau will forward decrypted file via email to Home Office intended recipient. If data is too large to email, the recipient will be advised and the data will be placed in ‘pick-up’ zone on the network folder for immediate retrieval and deletion.
  5. Bureau will send a confirmation email to the originator that the data has been sent to the Home Office recipient.
  6. Bureau will shred/delete Originator’s CD/DVD/email.

The possibility of potential fraudsters or mischief-makers posing as the Home Office could be addressed if the bureau published its own public key. As things stand the Central Cryptography Service is being run more like an internal postal service that simply receives messages from the outside before distributing them internally.

In fairness these procedures are much better than what existed previously. The Home Office expresses a strong preference for information sent to it to be encrypted and sets out procedures to handle this.

The Home Office said it was implementing the recommendations of the Hannigan report for improving the handling of data across Whitehall departments.

"The Home Office is determined to learn from earlier security breaches in Government and the programme initiated in response to the Hannigan report will help ensure that our systems and processes to protect personal data are as good as they can be. We are fully committed to implementing all of the recommendations in the report and have already established a programme to drive the work forward," it said.

"Many of the recommendations are already in effect in the Home Office and we recently launched a new, centralised encryption service at the Home Office. No personal information may be sent beyond the secure boundary of Government IT networks (e.g. GSI and PNN) without first being encrypted. Third parties sending personal information to the Home Office are also encouraged to encrypt their information.

"In addition to this, the Home Office already has in place a Hannigan-compliant system for reporting security incidents. Any breaches of security at the department will be taken very seriously and investigated thoroughly to avoid any possibility of recurrence." ®