Constant-Time Crypto
Definition
An implementation whose execution time, memory access pattern and power profile do not depend on the secret key or plaintext. The defence against timing, cache and power side channels. AES-NI is constant-time by hardware design; software AES with T-tables is not.
Related terms
- AEAD
- Authenticated Encryption with Associated Data. Combines confidentiality and integrity in one primitive. AES-GCM and ChaCha20-Poly1305 are the two modern standards. TLS 1.3...
- AES-NI
- AES New Instructions: hardware AES acceleration introduced on Intel Westmere (2010) and AMD Bulldozer (2011) and now ubiquitous. Single-cycle round operations make...
- Block Cipher
- A symmetric cipher that operates on fixed-size blocks (typically 64 or 128 bits) under a key. AES is a 128-bit-block cipher; DES...
- Mode of Operation
- The wrapping protocol that defines how a block cipher handles arbitrary-length data, what IV or nonce is used, and whether integrity is...
- Stream Cipher
- A symmetric cipher that produces a pseudo-random keystream which is XORed bit-by-bit or byte-by-byte with the plaintext. RC4 (legacy), ChaCha20 (current). Stream...
Explained in
- Symmetric Cryptosystems: DES, AES, RC4 and BlowfishAn implementation whose execution time, memory access pattern and power profile do not depend on the secret key or plaintext. The defence against timing, cache...