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fix(DiffieHellman): use each role's own private exponent - #1041
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SamuelSchlesinger wants to merge 2 commits into
Open
SamuelSchlesinger wants to merge 2 commits into
SamuelSchlesinger wants to merge 2 commits into
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SamuelSchlesinger
requested review from
arademaker,
chenson2018,
crei,
fmontesi and
sorrachai
as code owners
October 3, 2026 03:35
The evaluator expressed modulus equality as an implication, so a call with the wrong modulus accepted every result. Require modulus equality together with the expected computed value. Adds a regression check rejecting every result for both functions when the modulus differs, while retaining the valid role-evaluation checks. The field elements already have type `ZMod params.p`, so the corrected relation also avoids the old dependent casts. Depends on #1041 (the role-exponent fix); this PR targets that branch. Implemented with Codex.
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Alice computed her public message with Bob's exponent, and Bob computed his shared secret with Alice's exponent. Use Alice's exponent for her public message and Bob's exponent for his shared secret.
The regression checks assert all four role-specific outputs explicitly: Alice's public message is
g ^ a, Bob's isg ^ b, and each shared secret uses the receiving role's own exponent. Checking key agreement alone would miss these mistakes.Depends on #1040 (the shared-secret call-arity fix); this PR targets that branch.
Implemented with Codex.