Key information generation device and key information generation method

摘要

In initial generation (for example, shipping from the factory), a security device generates an identifier w specific to the security device, with the PUF technology, generates key information k (k=HF(k)) from the identifier w, generates encrypted confidential information x by encrypting (x=Enc(mk, k)) confidential information mk with the key information k, and stores the encrypted confidential information x and an authentication code h (h=HF′(k)) of the key information k, in a nonvolatile memory. In operation, the security device generates the identifier w with the PUF technology, generates the key information k from the identifier w, and decrypts the encrypted confidential information x with the key information k. At a timing where the identifier w is generated in the operation, the security device checks whether the current operating environment has largely changed from the initial generation (S311). If a change in operating environment is detected (S311→S312), the security device conducts a reset-up process (S312 to S315) of an authentication code h which is confidential information, and the encrypted confidential information x.