Computer Associates is set to buy Netegrity for $430m.
The firms expect the acquisition be complete in 90 days and have entered into a preliminary agreement until the deal is finalised.
Computer Associates said that it hopes the move will strengthen its eTrust Identity and Access Management portfolio: "We'd been looking at web authentication and single-sign-on and felt we needed to do some more work," said Simon Perry, VP of security strategy for Computer Associates.
"We felt we had a good product, but it didn't take us into different directions. Netegrity attracted us because of its technology integration [with eTrust], and it was well regarded by the analyst community."
When completed, Computer Associates said it expected to employ most of Netegrity's 400 employees. It added it bought the firm because it needed to improve the web-based features of eTrust.
Perry said that companies were looking to manage online customer access as well as internal employee identities.
"This is bringing in much stronger technology for us," said Perry. "Now we've got the ability to have an integrated approach and a single point of management. This is very exciting stuff."
Last month Netegrity faced embarrassment when one of its employee's laptops was stolen at Gartner's Security Conference in London. When asked his opinions on the incident, Perry said: "I think that we'll clearly be focussing that all people are aware of treating assets appropriately."