An apparatus and method for providing external bump-in-the-wire cryptographic capability to a legacy radio (which may or may not include embedded cryptography) includes an appliqué couplable to the legacy radio and to an intercom, handset, or other user device. The appliqué extracts and stores in memory radio status information from the legacy radio (channel information, cryptographic instructions, alarm conditions) by intercepting control signals, polling the legacy radio, or listening in on channels used by the legacy radio. If TSVCIS 2.1 or CMI-compatible encryption is required, the appliqué may encrypt or decrypt a message with the appropriate cryptographic keys based on the extracted radio status information. The appliqué may include a bump-in-the-wire device or a bump-in-the-connector device directly couplable to an intercom port of a vehicular mounted SINCGARS legacy radio.