Entropy & Random / SP 800-90A DRBG

What you will do: Instantiate HMAC_DRBG from a 32-byte entropy input, a nonce and a personalization string, then press Generate and Reseed while the Internal State Tracker shows the working key K, state value V and reseed_counter. Run the known-answer check to compare the same code with NIST vectors.

Worked example: Instantiate with the default personalization string and generate 32 bytes ten times: reseed_counter reaches 11, above the demo interval of 10, so a Reseed required banner blocks Generate until you press Reseed, which resets it to 1.

Runtime and privacy: The cryptographic exercise runs in this browser. Review the site privacy terms before entering sensitive material; use synthetic inputs for learning and evaluation.

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For your role

Developer / Engineer

Set the bytes and optional additional input, Generate several times and Reseed: the state tracker shows what your DRBG wrapper must keep between calls and when reseeding changes the output.

Security Architect

Instantiate HMAC_DRBG with a personalization string, then Generate and Reseed: the Internal State Tracker shows the Key and V vectors ratcheting, which is why a DRBG can be seeded once and reseeded on a schedule.

Researcher / Academic

Run the known-answer check: 16 NIST HMAC_DRBG vectors must match byte for byte and a one-bit flip in one entropy input must not — evidence the SP 800-90A Rev. 1 mechanism is computed correctly, and none about the entropy input.

Certification & Validation Engineer

Run the known-answer check: 16 NIST HMAC_DRBG vectors must match byte for byte and a one-bit flip must not — algorithm evidence for SP 800-90A Rev. 1, and none about the entropy input that seeds it.