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zeekay
f4765ea61c
Adds the Tier A formal-artifact cluster for protocols/frost (Lux profile of Komlo-Goldberg / IETF FROST). Mirrors luxfi/pulsar's Tier A structure adapted to Schnorr threshold signing. - proofs/easycrypt/FROST_N1.ec — Class N1 byte-equality reduction - proofs/easycrypt/FROST_N1_Refinement.ec — round-1/2/combine refinement - proofs/easycrypt/FROST_Ciphersuite_Ed25519.ec — Ed25519 ciphersuite - proofs/easycrypt/FROST_Ciphersuite_Secp256k1_Taproot.ec — BIP-340 ciphersuite - proofs/easycrypt/FROST_N4.ec — DKG public-key preservation - proofs/easycrypt/lemmas/FROST_CT.ec — constant-time obligations - proofs/easycrypt/AXIOM-INVENTORY.md — honest enumeration - proofs/lean-easycrypt-bridge.md — Lean↔EC bridge map - jasmin/lib/ + jasmin/single-party/ + jasmin/threshold/ — Jasmin scaffolds Plus shared scripts/check-high-assurance.sh that gates all three protocols (frost, cmp, bls) at admit budget 1/1 with skip-friendly jasminc and easycrypt invocations. Admit budget: 1/1 (one-line group-identity admit in FROST_N4 closure).
46 lines
1.6 KiB
Plaintext
46 lines
1.6 KiB
Plaintext
// FROST Lagrange coefficient computation in F_r.
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//
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// For a quorum Q and party index i in Q, this computes
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// lambda_i(0) = prod_{j in Q, j != i} (0 - x_j) / (x_i - x_j)
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// in F_r where r is the pinned ciphersuite's scalar field order.
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//
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// CT obligation: the loop bound is the quorum size |Q|, which is
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// PUBLIC (an adversary observing the session transcript already knows
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// the quorum). Inversion (1/(x_i - x_j)) must be constant-time per
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// the underlying scalar-field implementation.
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require "frost_params.jinc"
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// Compute lambda_i(0) for party i in quorum indexed by Q[0..n).
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// Inputs:
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// quorum_indices : array of party indices in the quorum (public).
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// n : |Q| (public).
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// my_idx_pos : position of THIS party's index in quorum_indices
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// (public).
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// Output:
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// lambda_out : 32-byte little-endian scalar mod r.
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//
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// CT: control flow + memory access depend only on (n, my_idx_pos);
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// scalar arithmetic is delegated to the ciphersuite's CT scalar API.
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inline
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fn frost_lagrange_at_zero(
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reg ptr u32[FROST_MAX_QUORUM] quorum_indices,
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reg u64 n,
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reg u64 my_idx_pos,
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reg ptr u8[FROST_SCALAR_BYTES] lambda_out
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) -> reg ptr u8[FROST_SCALAR_BYTES]
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{
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// TODO: jasmin implementation.
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//
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// Pseudocode:
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// lambda <- 1
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// for j in 0..n:
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// if j != my_idx_pos:
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// lambda <- lambda * (0 - x_j) * inv(x_i - x_j)
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// return lambda
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//
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// The (j != my_idx_pos) test branches on PUBLIC data only.
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// scalar_mul and scalar_inv must be CT per the ciphersuite.
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return lambda_out;
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}
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