pk/rsa: use correct invariant when checking parameter d #100
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It's d parameter is bigger than e ^ -1 mod LCM (p - 1) (q - 1) which is licit as long as d and e ^ - 1 are congruent with respect of LCM (p - 1) (q - 1). Signed-off-by: Pau Ruiz Safont <pau.safont@citrix.com>
The previous invariant didn't apply the modulus to d, which made it fail on some valid keys. Signed-off-by: Pau Ruiz Safont <pau.safont@citrix.com>
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…age-crypto-rng-mirage and mirage-crypto-rng-async (0.8.10) CHANGES: - Rsa.priv: require 1 = d * e mod (lam n). This allows interoperability with OpenSSL generated keys. Reported and fixed by @psafont in mirage/mirage-crypto#100.
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The correct invariant is
d ≡ e⁻¹ (mod λ(n)), this means that the modulus is applied to bothdande⁻¹, which was not done with the previous check.In practice this means that RSA keys using
d = (p - 1) * (q - 1)instead ofd = lcm (p - 1) (q - 1)could fail this test when they are valid.Note: (FIPS 186-4 is more strict and would use the check previously used, but I think it should be an optional check)