RSA (Rivest-Shamir-Adleman)
Type
Asymmetric, integer factorization-based
Key Lengths
2048, 3072, 4096 bits commonly used
Security Basis
Computational difficulty of factoring large integers
Primary Uses
Certificates, digital signatures, encryption, legacy PKI
Advantages
Mature ecosystem, broad compatibility, well-understood
Drawbacks
Large keys required, slower performance than elliptic curves
Notes: RSA remains the standard for many existing PKI deployments due to its extensive support across platforms and applications.
EC (Elliptic Curve Cryptography, ECDSA)
Type
Asymmetric, elliptic curve discrete logarithm-based
Key Lengths
256, 384, 521 bits (depending on curve)
Security Basis
Elliptic curve discrete logarithm problem hardness
Primary Uses
Digital signatures, key exchange, modern TLS and PKI
Advantages
Smaller keys, excellent performance, strong security
Drawbacks
Implementation complexity, critical curve parameter selection
Notes: NIST P-256 and P-384 curves are widely adopted in enterprise environments for their balance of security and efficiency.
EdDSA (Edwards-curve Digital Signature Algorithm)
Type
Asymmetric, elliptic curve (Edwards form)
Key Lengths
Ed25519 (256 bits), Ed448 (448 bits)
Security Basis
Twisted Edwards curves with deterministic signatures
Primary Uses
Secure messaging, SSH keys, next-generation PKI
Advantages
High performance, secure defaults, deterministic output
Drawbacks
Limited support in legacy systems and older libraries
Notes: Ed25519 has become the prevailing standard for new implementations requiring high security and performance.
MLDSA (Multivariate Lattice-based DSA, PQC)
Type
Asymmetric, post-quantum (lattice-based)
Key Lengths
Significantly larger than classical algorithms
Security Basis
Structured lattice problem hardness, quantum-resistant
Primary Uses
Post-quantum PKI, quantum-safe digital signatures
Advantages
Quantum attack resistance, modern cryptographic foundation
Drawbacks
Large keys and signatures, evolving standardization
Notes: Essential for organizations planning migration to quantum-safe cryptographic infrastructures.
SLHDSA (Stateless Hash-based DSA, PQC)
Type
Asymmetric, post-quantum (hash-based, stateless)
Key Lengths
Variable based on security parameters and hash function
Security Basis
Hash function security properties only
Primary Uses
Long-term signatures, firmware updates, high-assurance PKI
Advantages
Strong security proofs, minimal assumptions, stateless operation
Drawbacks
Large signature sizes, specific usage considerations
Notes: Ideal for environments demanding maximum assurance and long-term quantum resistance with minimal cryptographic assumptions.