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zeekay
256d44c165
Adds the Tier A formal-artifact cluster for protocols/cmp (Lux profile of CGGMP21 threshold ECDSA, CCS '21 / ePrint 2021/060). Mirrors luxfi/pulsar's Tier A structure adapted to CCS '21's 4-round keygen + 3-round presign + 1-round online sign decomposition. - proofs/easycrypt/CGGMP21_N1.ec — Class N1 byte-equality reduction - proofs/easycrypt/CGGMP21_N1_Refinement.ec — keygen/presign/sign refinement - proofs/easycrypt/CGGMP21_Paillier.ec — Paillier additive homomorphism - proofs/easycrypt/CGGMP21_ZK.ec — 17 ZK subprotocol cluster obligation - proofs/easycrypt/CGGMP21_N4.ec — refresh / proactive rotation - proofs/easycrypt/lemmas/CGGMP21_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/presign/ + jasmin/threshold/ Admit budget: 1/1 (same one-line group-identity admit as FROST_N4). ZK cluster obligation surface honest: 17 subprotocols enumerated, mechanization is multi-year program documented in AXIOM-INVENTORY.md §closure roadmap.
77 lines
3.0 KiB
Plaintext
77 lines
3.0 KiB
Plaintext
// CGGMP21 Presign Round 3 — finalize presignature (Lux profile).
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//
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// Reference: CCS '21 §5.1 Round 3; mirrors Go reference at
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// `~/work/lux/threshold/protocols/cmp/presign/round3.go`.
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//
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// -----------------------------------------------------------------------------
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// Algorithm
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// -----------------------------------------------------------------------------
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//
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// After Round 2:
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// - Each party holds (alpha_{i,j}, beta_{j,i}) such that
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// alpha_{i,j} + beta_{j,i} = k_i * gamma_j (mod n) for each peer j.
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// - Define delta_i = sum_j (alpha_{i,j} + beta_{j,i})
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// = sum_j (k_i * gamma_j) = k_i * (sum_j gamma_j)
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// Note: this includes gamma_i itself (i = j case).
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// - Define Gamma_i = gamma_i * G (on secp256k1).
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// - Define chi_i: per CCS '21 §5.1, the multiplication share of
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// k_i * x_i (the secret share contribution).
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//
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// In Round 3 each party:
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// 1. Broadcasts delta_i (in F_n).
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// 2. Broadcasts Gamma_i (point on secp256k1).
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// 3. Receives delta_j, Gamma_j from all peers.
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// 4. delta = sum_j delta_j // public
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// 5. Gamma = sum_j Gamma_j // public point
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// 6. delta = k * gamma where k = sum k_i, gamma = sum gamma_i.
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// ZK invariant: delta * G = k * Gamma.
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// 7. R = (delta^{-1} * Gamma) // = (k * gamma)^{-1} * (gamma * G)
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// // = k^{-1} * G PUBLIC
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// 8. r = R.x mod n
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//
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// Outputs:
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// presignature: (R, r, k_inv_share, chi_share) — k_inv_share and
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// chi_share are SECRET, R and r are PUBLIC.
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//
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// CT obligations:
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// - All scalar operations CT in (k_i, gamma_i, alpha_{i,*}).
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// - delta^{-1} requires CT modular inverse.
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require "../lib/cmp_params.jinc"
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require "../lib/paillier.jinc"
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inline
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fn cmp_presign_round3(
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reg ptr u8[CMP_SCALAR_BYTES] share,
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reg ptr u8[64] nonce_state,
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reg ptr u8[CMP_SCALAR_BYTES * CMP_MAX_QUORUM * 2] mta_state,
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reg ptr u8[16] session_id,
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reg u32 my_idx,
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reg u64 n_peers,
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reg ptr u8[CMP_POINT_BYTES] R_out,
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reg ptr u8[CMP_SCALAR_BYTES] r_out,
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reg ptr u8[CMP_SCALAR_BYTES] k_inv_share_out,
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reg ptr u8[CMP_SCALAR_BYTES] chi_share_out
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) -> reg ptr u8[CMP_POINT_BYTES],
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reg ptr u8[CMP_SCALAR_BYTES],
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reg ptr u8[CMP_SCALAR_BYTES],
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reg ptr u8[CMP_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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// delta_i <- k_i * gamma_i + sum_{j!=i} (alpha_ij + beta_ji)
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// Gamma_i <- gamma_i * G
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// {broadcast (delta_i, Gamma_i)}
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// {receive (delta_j, Gamma_j)}
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// delta <- sum_j delta_j
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// Gamma <- sum_j Gamma_j
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// R <- delta^{-1} * Gamma // PUBLIC
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// r <- R.x mod n
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// k_inv_share_out <- (something derived from k_i, delta) // SECRET
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// chi_share_out <- (something derived from k_i * x_i) // SECRET
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//
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// CT: scalar_inv (delta^{-1}) and all scalar arithmetic must be CT.
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return R_out, r_out, k_inv_share_out, chi_share_out;
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}
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