Kyber (ML-KEM)

Kyber is a lattice-based key encapsulation mechanism standardized as ML-KEM.

Overview

• Type: Key Encapsulation Mechanism (KEM)
• Standard: FIPS 203 (ML-KEM)
• Security basis: Module Learning With Errors (MLWE)

Parameter sets

Variant	Security level	Public key	Ciphertext	Shared secret
Kyber-512	Level 1	800 bytes	768 bytes	32 bytes
Kyber-768	Level 3	1184 bytes	1088 bytes	32 bytes
Kyber-1024	Level 5	1568 bytes	1568 bytes	32 bytes

QNSP usage

• Default: Kyber-768 (ML-KEM-768)
• Use cases: TLS key exchange, key wrapping, hybrid encryption

Operations

Key generation

Generate public/private keypair for encapsulation.

Encapsulation

Given public key, produce ciphertext and shared secret.

Decapsulation

Given private key and ciphertext, recover shared secret.

Hybrid mode

Combined with X25519:

1. X25519 key exchange → shared secret 1
2. Kyber encapsulation → shared secret 2
3. HKDF(secret1 || secret2) → final key

Performance

Operation	Time (typical)
KeyGen	~50 μs
Encaps	~60 μs
Decaps	~70 μs