Post-quantum vs classical signatures: ECDSA, RSA, and Dilithium compared
Classical signatures (ECDSA, RSA) and post-quantum signatures (ML-DSA/Dilithium) solve the same problem — proving authenticity — but rest on different hardness assumptions. One of those assumptions is broken by a large quantum computer.
The security difference
ECDSA and RSA rely on the difficulty of discrete logarithms and integer factorization, both broken by Shor’s algorithm on a sufficiently large quantum computer. Dilithium relies on lattice problems with no known efficient quantum attack. That is the entire reason NIST standardized post-quantum replacements.
What changes for developers
Mostly size. Dilithium-2 keys (~1.3 KB) and signatures (~2.4 KB) are larger than ECDSA’s (tens of bytes), so you budget more bandwidth and storage. Operations stay fast. The API shape — generate, sign, verify — is unchanged, so migration is mostly plumbing.
Hybrid is the prudent default
While the ecosystem matures, deploy in hybrid mode (classical + post-quantum together) so you are no weaker against classical attacks and protected against quantum ones. Post-quantum schemes are resistant to known classical and quantum attacks per NIST — not unbreakable, but the right foundation to build on now.
Try it yourself — live, free, verifiable in 30 seconds:
Compare them with the PQC API →