Updated from 4:28 p.m. EDT

Investors in Secure Computing ( SCUR) weren't feeling too secure after a second-quarter earnings shortfall drove shares down 30% in postclose action.

The San Jose, Calif., network security company said late Tuesday that it expects to make 5 or 6 cents a share, excluding unusual items, on revenue of $38.5 million to $39 million. Analysts surveyed by Thomson Financial were looking for an 11-cent profit on sales of $44 million.

Secure Computing didn't explain the shortfall, though it added that it expects to lose $2.3 million to $2.8 million on a generally accepted accounting principles basis, before recognition of a gain related to a tax valuation allowance that was not included in guidance.

Shares fell $2.43 late Tuesday to $5.64.

Secure Computing separately announced it would acquire privately held CipherTrust, a messaging security company, for $273.6 million.

The figure comprises $185 million in cash, 10 million shares of Secure Computing common stock and a $10 million seller note that is subject to performance. At the close of the deal, CipherTrust shareholders will have an approximately 14% ownership position in Secure Computing.

As part of the agreement, Secure Computing will receive a credit facility from Citigroup ( C) for a $115 million term loan and $20 revolving credit. The transaction is expected to close by Sept. 8, the company said.

Secure Computing expects CipherTrust to grow revenue by $15 million to $20 million in 2006, and add $80 million to revenue in 2007, depending on the closing date of the deal. The transaction will be break-even for pro forma EPS by mid-2007 and add to pro forma earnings in the second part of 2007.

CipherTrust CEO Jay Chaudhry will join the company's board as vice chairman and will take on the job of chief strategy officer.