ISO 13491-1:2007 specifies the requirements for secure cryptographic devices (SCDs) based on the cryptographic processes defined in ISO 9564, ISO 16609 and ISO 11568.ISO 13491-1:2007 has two primary purposes: to state the requirements concerning both the operational characteristics of SCDs and the management of such devices throughout all stages of their life cycle, and to standardize the methodology for verifying compliance with those requirements.Appropriate device characteristics are necessary to ensure that the device has the proper operational capabilities and provides adequate protection for the data it contains. Appropriate device management is necessary to ensure that the device is legitimate, that it has not been modified in an unauthorized manner (e.g. by “bugging”) and that any sensitive data placed within the device (e.g. cryptographic keys) has not been subject to disclosure or change.Absolute security is not achievable in practical terms. Cryptographic security depends upon each life cycle phase of the SCD and the complementary combination of appropriate management procedures and secure cryptographic characteristics. These management procedures implement preventive measures to reduce the opportunity for a breach of SCD security. These aim for a high probability of detection of any unauthorized access to sensitive or confidential data, should device characteristics fail to prevent or detect the security compromise.Annex A provides an informative illustration of the concepts of security levels described in ISO 13491-1:2007 as being applicable to SCDs.