Dictionary · NIST SP 800-90A

Backtracking resistance is provided relative to time T if there is assurance that an adversary who has knowledge of the internal state of the Deterministic Random Bit Generator (DRBG) at some time subsequent to time T would be unable to distinguish between observations of ideal random bitstrings and (previously unseen) bitstrings that were output by the DRBG prior to time T. The complementary assurance is called Prediction Resistance.

A Random Bit Generator (RBG) that includes a DRBG mechanism and (at least initially) has access to a source of entropy input. The DRBG produces a sequence of bits from a secret initial value called a seed, along with other possible inputs. A DRBG is often called a Pseudorandom Number (or Bit) Generator. Source of entropy input. The DRBG produces a sequence of bits from a secret initial value called a seed, along with other possible inputs. A DRBG is often called a Pseudorandom Number (or Bit) Generator.

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.

An RBG that (when working properly) produces outputs that have full entropy. Contrast with a DRBG. Other names for non-deterministic RBGs are True Random Number (or Bit) Generators and, simply, Random Number (or Bit) Generators.

Prediction resistance is provided relative to time T if there is assurance that an adversary who has knowledge of the internal state of the DRBG at some time prior to T would be unable to distinguish between observations of ideal random bitstrings and bitstrings output by the DRBG at or subsequent to time T. The complementary assurance is called Backtracking Resistance.

A device or algorithm that outputs a sequence of binary bits that appears to be statistically independent and unbiased. An RBG is either a DRBG or an NRBG.