Understand and use encryption
Secure email, browser, and file transfer software available in the UWICK is configured to protect your password, but it does not necessarily protect the content of messages and files you send over the networks. Additional encryption methods are available to keep sensitive information such as patient, financial, or employee records private. The following articles describe the concepts of encryption and how it is being used at the UW.
[Note: The following text is based on the article Encryption Technology that was published in Windows on Computing, Winter 1999.]
Encryption, or information scrambling, technology is an important security tool. Properly applied, it can provide a secure communication channel even when the underlying system and network infrastructure is not as secure as it should be. This is particularly important when data passes through shared systems or network segments where multiple people may have access to the information. In these situations, sensitive data--and especially passwords--should be encrypted in order to protect them from unintended disclosure or modification.
Encryption is a procedure that involves a mathematical transformation of information into scrambled gobbledygook, called "cipher text." The computational process (an algorithm) uses a key--actually just a big number associated with a password or pass phrase--to compute or convert plain text into cipher text with numbers or strings of characters. The resulting encrypted text is decipherable only by the holder of the corresponding key. This deciphering process is called decryption.
Several approaches to encryption are being used and explored at the UW. Even though substantial barriers to widespread deployment remain, we are making significant progress. For one thing, there are many different and incompatible encryption techniques available, and not all the software we need to use implements a common approach. In the long run, effective use of encryption will require vendors to agree on which methods and standards to follow.
Private-key and public-key cryptography
Two different cryptographic methods are being applied in computer security: private-key and public-key encryption. In private-key encryption, the sender and receiver of information share a secret--a key that is used for both encryption and decryption. In public-key encryption, two different mathematically related keys (a key pair) are used to encrypt and decrypt data. Information encrypted with one key may only be decrypted by using the other half of the key pair.
One of the most common uses of public-key technology is to provide a secure communication channel between computer programs, although private-key techniques can be used for this, too. A prime example of public-key technology is the SSL protocol, often used to protect information sent between Web browsers and Web servers.
MyUW uses the SSL protocol to provide a secure communication channel in which UW students, faculty, alumni, and staff authenticate themselves, using a UW NetID and password, before doing tasks. Via this secure communication channel:
- Faculty and staff update their directory information
- Students look at their class schedule
- All can use WebPine
The SSL protocol can also be used to protect information exchanged between email clients and UW's mail servers. Examples of email clients which support SSL are: Pine, PC-Pine, Outlook Express, Netscape Messenger, WebPine, and Eudora.
When using a public-key system for personal authentication or secure messaging, you keep one key secret. The second (public) key can then be distributed to anyone. Some people even put their public key on their personal Web page; it might also be stored on a public-key server.
The secret (or private) key in a public-key cryptographic system is never transmitted or shared. For example, when using this method for client-side authentication, the server sends some data to your client program. The client uses your private key to encrypt that data. Using your public key, the server will attempt to decrypt the returned data, and, if successful, know that it has established communication with "the real you."
Cryptographic authentication (protecting your UW NetID and password)
Encryption can be used to support our authentication, integrity, privacy, and non-repudiation objectives. Let's focus on authentication.
Providing a way to authenticate yourself to a computer system without sending your password "in the clear" is an important security goal. Passwords sent without encryption may be discoverable by others if sent through or to insecure network segments or systems. Several approaches are being used to avoid the clear-text password problem:
- Methods for sending passwords through secure (encrypted) channels are beginning to be deployed. The UW's central servers (including Homer and Dante) no longer accept clear text passwords.
- Shared network segments are gradually being replaced by "switched" network segments. The newer, switched network technology greatly reduces the opportunity for "sniffing" or eavesdropping on people's conversations.
- Cryptographic authentication systems, which do not rely on transmitting passwords, are being deployed.
The UW's central computers support the Kerberos authentication system (based on private-key cryptography), ssh, and SSL (explained above) all of which protect your password from going across the network in the clear.
