Plain-language definitions
Glossary
Every term that gets a hover note on the rest of the site, in one place.
- AEAD
- Authenticated encryption with associated data. It encrypts a message and proves nobody changed it.
- ASCON
- The lightweight cipher family NIST standardized in SP 800-232 for small devices.
- BigCrush
- The most demanding battery in TestU01: 106 tests run against a stream of random bits.
- Bijection
- A one-to-one mapping. Every input has exactly one output, so nothing is lost.
- CAGE code
- Commercial and Government Entity code. A five-character ID the US government assigns to suppliers.
- Constant-time
- Takes the same number of clock cycles whatever the secret data is, so timing reveals nothing.
- Harvest-now-decrypt-later
- Recording encrypted traffic today so it can be decrypted once quantum computers can break the key exchange.
- Heap
- The pool of memory a program requests at runtime (malloc). Small firmware often cannot afford it.
- HIL
- Hardware-in-the-loop. Testing on real boards with real instruments instead of simulators.
- KAT
- Known answer test. Fixed inputs and outputs used to check that an implementation is correct.
- KEM
- Key encapsulation mechanism. A public-key method two devices use once to agree on a shared secret key.
- Keystream
- The pseudo-random byte sequence a stream cipher XORs with your data.
- Nonce
- A number used once per message under a key (64-bit standard or 256-bit extended
X256in APEX-256). Reusing one under the same key can break a stream cipher. - NUMS
- Nothing up my sleeve. A constant chosen in a verifiable way so it can't hide a back door.
- PLC
- Programmable logic controller. A small industrial computer that runs machinery.
- Post-quantum
- Cryptography designed to stay secure against attacks by large quantum computers.
- PractRand
- A statistical test suite that hunts for patterns in random-looking data. We ran it to 32 TB.
- S-box
- Substitution box. A lookup table many ciphers use. Table lookups can leak through cache timing.
- SBIR
- Small Business Innovation Research. A federal program that funds early technology from small companies.
- SCADA
- Supervisory control and data acquisition. The systems that monitor and run utilities and plants.
- Side-channel
- An attack that reads physical leakage (timing, power draw, radio emissions) instead of breaking the math.
- SMT
- Satisfiability modulo theories. A way to prove a property holds for every input, or to find one that breaks it.
- Stream cipher
- A cipher that makes a keystream and XORs it with the data, so ciphertext is the same length as plaintext.
- SWaP-C
- Size, Weight, Power, and Cost. The four budgets that decide what a device can carry.
- UEI
- Unique Entity ID. The identifier SAM.gov assigns to organizations that do business with the government.
- UNSAT
- Unsatisfiable. The solver found no input that breaks the property. That is the result you want.
- Z3
- Microsoft's SMT solver. It checks a claim by searching for a counterexample.