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What is Deterministic Random Bit Generator (DRBG) Mechanism?
Definition:
The portion of an RBG that includes the functions necessary to instantiate and uninstantiate the RBG, generate pseudorandom bits, (optionally) reseed the RBG and test the health of the DRBG mechanism.
SOURCE: SP 800-90A
What Is DRBG in Cybersecurity?
In cybersecurity, a Deterministic Random Bit Generator (DRBG) is a mechanism that produces a sequence of bits from a secret initial value (seed) using a defined algorithm, often referred to as a pseudorandom number generator (PRNG). DRBGs are crucial for generating cryptographically secure random numbers, essential for tasks like key generation and data encryption.
- Deterministic Nature:
DRBGs are deterministic, meaning that given the same initial seed and algorithm, they will always produce the same sequence of bits.
- Cryptographic Security:
To be suitable for cryptographic applications, a DRBG must be unpredictable to anyone who doesn’t know the secret seed.
- NIST SP 800-90A:
The National Institute of Standards and Technology (NIST) publication SP 800-90A provides recommendations for random number generation using DRBGs, including specifications for various DRBG mechanisms.
- DRBG Mechanisms:
SP 800-90A specifies several DRBG mechanisms, including Hash-based DRBG (Hash_DRBG), HMAC-based DRBG (HMAC_DRBG), and Counter-based DRBG (CTR_DRBG).
- HMAC DRBG:
The HMAC DRBG mechanism uses a Hash-based Message Authentication Code (HMAC) function to produce a secret key, which is then used to generate a sequence of bits.
- Entropy Sources:
DRBGs often rely on entropy sources (sources of randomness) to initialize the seed, ensuring the initial randomness.
- Implementation Validation:
DRBGs should be designed to be tested and validated to ensure correct implementation and adherence to security requirements.
- CAVP:
The Cryptographic Algorithm Validation Program (CAVP) provides a method for validating DRBG implementations.
