Director: Simon S. Lam (more publications)

The first secure sockets layer: SNP preceded SSL by several years

In 1991, we received a grant from the National Security Agency to investigate how to apply a theory of modules and interfaces of ours to security verification [4].  At that time, there were three well-known authentication systems built (MIT's Kerberos) or being developed (DEC's SPX, and IBM's KryptoKnight).  We recognized that all of these systems suffered from a common drawback, namely, they did not export a clean and easy-to-use interface that could be readily used by Internet applications.  For example, it would take a tremendous amount of effort to “kerberize” an existing distributed application.

Toward the goal of "secure network programming for the masses," we invented secure sockets as a high-level abstraction suitable for securing Internet applications.  In 1993, we designed and built a prototype of the first secure sockets layer, named Secure Network Programming (SNP).  SNP, designed as an application sublayer on top of sockets, provides a user interface closely resembling sockets.  This resemblance was by design so that security could be retrofitted into existing socket programs with only minor modifications.  SNP's secure sockets support both stream and datagram semantics with security guarantees (i.e., data origin authenticity, data destination authenticity, data integrity, and data confidentiality.)  Many of the design choices in SNP can be found in today's secure sockets layer used between browsers and Internet servers, including: placing authenticated communication endpoints in the application layer, use of public key cryptography for authentication, a handshake protocol for establishing session state including a shared secret, use of symmetric key cryptography for data confidentiality, and managing contexts and credentials in the secure sockets layer.

We articulated the case for secure sockets in a paper presented at the USENIX Summer Technical Conference, June 1994 [0].  We also presented our system design together with performance measurement results from our prototype implementation to clearly demonstrate the practicality of a secure sockets layer. Today, the secure sockets layer, SSL, later designed and built by Netscape is widely used for securing communications between browsers and servers, as well as other Internet applications.  (Netscape Communications was founded as a company in 1994 about the time when our USENIX paper was published.)

SNP won the 2004 ACM Software System Award.

Main publication

[0] Thomas Y. C. Woo, Raghuram Bindignavle, Shaowen Su, and Simon S. Lam, "SNP: An Interface for Secure Network Programming," Proceedings USENIX Summer Technical Conference, Boston, June 1994; also available from  http://www.usenix.org/publications/library/proceedings/bos94/ .

Supporting work and grants

[1] Thomas Y. C. Woo, Authentication and Authorization in Distributed Systems, Ph.D. Dissertation, Dept. of Computer Sciences, UT-Austin, August 1994 (supervisor: Simon S. Lam).

[2] Raghuram Bindignavle, Secure Network Programming, M.A. Thesis, Dept. of Computer Sciences, UT-Austin, December 1994 (supervisor: Simon S. Lam).

[3] Thomas Y. C. Woo and Simon S. Lam, "Design, verification, and implementation of an authentication protocol," Proceedings IEEE ICNP, Boston, October 1994.

[4] Simon S. Lam (PI/PD), "Applying a Theory of Modules and Interfaces to Security Verification," NSA INFOSEC University Research Program grant no. MDA 904-91-C-7046, 1991-94.

[5] Simon S. Lam (PI/PD), "A Proof Methodology for Authentication Protocols," NSA INFOSEC University Research Program grant no. MDA 904-93-C-4089, 1993-96.