Many of us have been watching the on-going drama between RIM (makers of the ubiquitous Blackberry) and various governments around the world. Governments have been successfully pressuring RIM to provide access to their internal messaging servers in order to get access to encrypted messages sent and received by Blackberry users. I think RIM has been trying to fight this access as best they can. After all, one of their key product messages is around the security of their systems. In spite of that I suspect some governments have been successful in getting at least limited access to the Blackberry servers that process secure messages.
At first I was puzzled by this story when it started to emerge. I mistakenly thought that the private key needed to decrypt a message was stored on the receiver’s Blackberry and that the intermediate message servers would not have the key necessary to decrypt a message. I was apparently wrong about this architecture and it turns out that the Blackberry message servers do have the ability to decrypt messages in transit. That ability puts RIM in the uncomfortable headlights of law enforcement and security agencies around the world.
People have been asking me if a similar situation exists with other common encryption technologies. For example, when I encrypt a file with PGP can it be decrypted by someone (A government? A credit card thief?) before it reaches the intended recipient. Before the drama with RIM I was not hearing this question, but now I think many people are wondering about it.
The short answer is to the question is No: When you encrypt a file with PGP it is not possible to decrypt it before it gets to the intended recipient. PGP is based on the widely used public/private key encryption technology deployed in many secure systems such as VPNs, web browsers, and secure FTP. When I encrypt some information with a public key, only the person holding the private key can decrypt the information. As long as I protect my private key an intermediary can’t decrypt a message intended only for me. Almost all of our assumptions about security depend on this fact.
Is this system perfect? No. As a recipient of secure messages I may inadvertently disclose my private key or lose it by failing to protect it properly. Also, I may be legally compelled by a government agency to relinquish it. Many governments are now requiring people to disclose their private keys and passwords when ordered by a court to do so. You might think that you can’t be compelled to give up a password or private key, but I think that resolve might fade after a few days of sitting in a jail cell. The bottom line is this: public/private key technology is the best method we have of protecting sensitive information. When done well it prevents anyone but an intended recipient from reading the sensitive information. But it also means that you have to pay attention to how you manage and protect encryption keys. Proper encryption key management is essential to any data protection method you use. We’ll be talking more about this in the days ahead.