Abstract: A system is disclosed for securing a device from invasive and noninvasive tampering, one such device being a printer assembly for use in a value printing system, such as a postal mailing system. The system is comprised of a Decryption Microcomputer operable for decrypting the input data to be printed in accordance with a valid cipher key, the encrypted data and key being provided by another device, such as a postal meter. The cipher key is stored within a Tamper Latch readably coupled to the Microcomputer for providing the key to the Microcomputer. In addition, the Tamper Latch has a wire of small cross-sectional area connected thereto such that the presence of the wire is operable for defining a portion of the cipher key. To provide further security from tampering the Microcomputer, Latch and wire are embedded within a potting material.