The Dallas security software vendor Entrust Inc., which has agreed to sell itself to the private-equity firm Thoma Bravo LLC, attracted three more suitors during its "go-shop" period, which ended last week.

Entrust, which develops products and services for digital identities, did not identify the potential buyers, saying in a regulatory filing only that it had received "written, nonbinding indications of interest" at prices higher than the $1.85 per share that Thoma Bravo agreed to pay last month in cash.

The vendor said that it intends to continue negotiations with each of these parties. However, Entrust also recommended that shareholders vote for the Thoma Bravo deal at a meeting scheduled for June 8.

The filing also included a response from Thoma Bravo, which cited "the substantial conditionality in each of the three proposals" and threatened legal action if the deal fails to go forward.