Cryptographic Algorithms Used With SSL

Cipher suites define the following aspects of SSL communication:

• The key exchange Algorithm

• The encryption cipher

• The encryption cipher key length

• The message authentication method

The SSL protocol supports many ciphers. Clients and servers can support different cipher suites, depending on factors such as the version of SSL they support, and company policies regarding acceptable encryption strength. The SSL handshake protocol determines how the server and client negotiate which cipher suites they use to authenticate each other, to transmit certificates, and to establish session keys.

SSL 2.0 and SSL 3.0 protocols support overlapping sets of cipher suites. Administrators can enable or disable any of the supported cipher suites for both clients and servers. When a client and server exchange information during the SSL handshake, they identify the strongest enabled cipher suites they have in common and use those for the SSL session. Decisions about which cipher suites to enable depend on the sensitivity of the data involved, the speed of the cipher, and the applicability of export rules.

Key-exchange algorithms like KEA and RSA govern the way in which a server and client determine the symmetric keys they use during an SSL session. The most commonly used SSL cipher suites use the RSA key exchange.

The list of ciphers enabled for Directory Server, and also the list of ciphers supported by Directory Server can be obtained with the dsconf command. For information about using the dsconf command to list available ciphers and manage ciphers, see Choosing Encryption Ciphers in Sun Java System Directory Server Enterprise Edition 6.2 Administration Guide.

Support for ciphers is provided by the Network Security Services, NSS, component. For details about NSS, see theNSS project site.