On: PuTTY vulnerability vuln-p521-bias

[eyegor]

Despite being fairly old, many systems still don't support eddsa. As an example, the reference browser/ca spec doesn't allow it: https://cabforum.org/working-groups/server/baseline-requirem.... Last I tried, even let's encrypt won't grant an ed25519 cert despite it being in tls 1.3 (2018?).

[throw0101c → eyegor]

> Last I tried, even let's encrypt won't grant an ed25519 cert despite it being in tls 1.3 (2018?).

Talk to the CA/Browser Forum. §6.1.5 Keys Sizes:

> For RSA key pairs the CA SHALL:

> * Ensure that the modulus size, when encoded, is at least 2048 bits, and;

> * Ensure that the modulus size, in bits, is evenly divisible by 8.

> For ECDSA key pairs, the CA SHALL:

> * Ensure that the key represents a valid point on the NIST P-256, NIST P-384 or NIST P-521 elliptic curve.

> No other algorithms or key sizes are permitted.

* https://cabforum.org/uploads/CA-Browser-Forum-TLS-BRs-v2.0.2...

* https://cabforum.org/working-groups/server/baseline-requirem...

Ed25519 (and Ed448) was only 'recently' approved by NIST FIPS 186-5 in February 2023.

[GoblinSlayer → eyegor]

Then make your own CA.