Techniques for assuring a receiver's non repudiation of a communication are provided via cooperation with a secure device. A secure device operates within a local environment of a receiver and exchanges certificates with a sender via the receiver. The sender encrypts data in a communication with the receiver. Separately, the sender sends an encrypted version of a decryption key to the receiver. The receiver presents the encrypted version of the key to the secure device and the secure device supplies the decryption key for use by the receiver to decrypt the previously sent encrypted data.