| 摘要 |
A method and apparatus for protecting encryption key codes from disclosure and improper usage. To initialize the encryption system, a source number is randomly-generated at a master unit and passed over secure transmission link to a slave unit. Both the master and slave unit perform a non-invertible transformation on the source number to generate two identical master code keys which are then stored in non-volatile memories in both the central site and the slave unit. The source number in each unit is then erased or destroyed. Subsequently, during an information transfer session between the master unit and the slave unit which takes place over an insecure transmission link, the stored master key is used to authenticate the slave unit and may be used to securely transfer additional encrypting keys. Various mechanical methods are used to make the slave unit secure so that it is difficult to extract the master key information from the unit without causing obvious physical damage to the unit. Even if the master key code is extracted, it cannot be loaded into an undamaged unit due to the non-invertible transformation circuitry in that unit; the original source number is required, but is no longer available or derivable. Additional embodiments disclose modifications to conventional key-loader apparatus using the non-invertible transform technique to protect key codes stored in the key-loader from disclosure or improper usage. Apparatus is also disclosed which uses either a non-invertible transform or a cryptographic technique to authenticate key-loader apparatus from a central location. |
