DRBG support information

Here is some additional information about the DRBG support implementation in Network OS.

1. There are no interfaces for external users to collect the DRBG generated by the crypto module. Applications that run as part of crypto module request and obtain the DRBG generated through library API calls. All the DRBG functions required for SP800-90A are invoked to generate and test the random bytes before providing it to the application.

2. Design of the implementation mandates validating every bit of the random value generated during the generation and timely re-seeding. Implementation also handles the un-instantiation to ensure that the residual values are not used for seeding.

   The implementation includes Health testing during all stages of DRBG generation: instantiate, seed, generate, reseed and un-instantiate.

3. The implementation utilizes CTR based DRBG mechanism with AES 256 cryptographic primitive for the generation of random numbers.
4. The implementation uses multiple entropy input sources to ensure that the entropy pool is full for generation of random bytes. In addition, the implementation always employs /dev/random to ensure the security strength of the entropy bits.
5. The implementation employs CTR-based DRBG mechanism with AES-256 cryptographic primitive with additional features to ensure stronger DRBG. Features included are predication resistance, additional input and personalization string.
6. DRBG mechanism functions are distributed in the implementation and hence no mechanisms are required to protect confidentiality and Integrity of the internal state.
7. The implementation uses CTR-based DRBG mechanism with derivation function.
8. In addition to the health test listed in SP800-90A, continuous random number generation tests are run on the bytes that are generated.
9. The DRBG health tests are run at an interval of every (1<<24) iterations of DRBG generation, which ensures that even the larger requirement for random numbers are validated.

   DRBG health tests are instantiated, seeded and generated for every requirement to generate the random number.

10. The DRBG functions can be tested in the implementation by power-cycle of the switch, key generation or any request for random numbers.
11. The SP800-90A DRBG implementation is part of the library whose installation is controlled within Extreme and can be downloaded on the crypto-module only through RSA 2048 and SHA256 verification.