PKA key algorithms

Public key cryptography uses a key pair consisting of a public key and a private key.

The PKA public key uses one of the following algorithms:

CRYSTALS-Kyber Key Encapsulation Method (Kyber-KEM)

CRYSTALS-Kyber is an IND-CCA2-secure key encapsulation mechanism (KEM), whose security is based on the hardness of solving the learning-with-errors (LWE) problem over module lattices. CRYSTALS-Kyber lists three different parameter sets aiming at different security levels. Specifically, Kyber-768 targets security of AES-192, and Kyber-1024 targets security of AES-256.

Rivest-Shamir-Adleman (RSA)

The RSA algorithm is the most widely used and accepted of the public key algorithms. It uses three quantities to encrypt and decrypt text: a public exponent (PU), a private exponent (PR), and a modulus (M). Given these three and some cleartext data, the algorithm generates ciphertext as follows:

ciphertext = cleartextPU  (modulo M)

Similarly, the following operation recovers cleartext from ciphertext:

cleartext = ciphertextPR  (modulo M)

Elliptic Curve Cryptography (ECC)

Elliptic curve cryptography (ECC) is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. One of the main benefits in comparison with non-ECC cryptography is the same level of security provided by keys of smaller size. CCA uses ECC for digital signatures and symmetric keys using the Diffie-Hellman key agreement scheme.

Elliptic Curve Digital Signature Algorithm (ECDSA and EdDSA)

The ECDSA and EdDSA algorithms use elliptic curve cryptography (an encryption system based on the properties of elliptic curves) to provide a variant of the Digital Signature Algorithm.

CRYSTALS-Dilithium Digital Signature Algorithm (CRDL-DSA)

CRYSTALS-Dilithium is a lattice-based digital signature scheme whose security is based on the hardness of finding short vectors in lattices. The CRYSTALS-Dilithium Digital Signature Algorithm (CRDL-DSA) is a quantum safe algorithm (QSA) and is a member of the CRYSTALS (Cryptographic Suite for Algebraic Lattices) suite of algorithms. The strength of a CRYSTALS-Dilithium key is represented by the size of its matrix of polynomials. For example, CRYSTALS-Dilithium (6,5) has a matrix size of 6x5. The larger the matrix size, the stronger the key. CRYSTALS-Dilithium keys can only be used for digital signature generation and verification (see Digital Signature Generate (CSNDDSG) and Digital Signature Verify (CSNDDSV)).

The required hash method for CRYSTALS-Dilithium DSA is SHAKE-256.