Learn
Short, technical guides to how digital signatures actually work — the algorithms, the byte-level formats, and the configuration mistakes that make verification fail. Written for the moments when a signature refuses to verify and the error message tells you nothing.
Algorithms
ECDSA vs RSA: which signature algorithm and when
Key and signature sizes at equal security, signing vs verification speed, where each algorithm dominates (TLS, SSH, JWT, blockchains), the ECDSA nonce problem — and what the post-quantum timeline means for both.
JWT
ES256 vs RS256 for JWTs: how to choose and how not to get burned
What the alg names actually mean, why ES256 tokens are ~250 bytes smaller, the algorithm-confusion mistake that breaks verification guarantees, and why JWS signatures are raw r‖s — not DER.
Formats
ECDSA signature formats: DER vs raw (P1363), high-S and cross-library pitfalls
One signature, two encodings. How ASN.1 DER and fixed-length raw r‖s differ byte by byte, which libraries default to which, and why high-S signatures verify in one stack and get rejected in another.
Prefer to poke at real bytes? The Signature Lab tools run entirely in your browser.