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Diffstat (limited to 'src/multisig/multisig_clsag_context.h')
| -rw-r--r-- | src/multisig/multisig_clsag_context.h | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/src/multisig/multisig_clsag_context.h b/src/multisig/multisig_clsag_context.h new file mode 100644 index 000000000..5017e8688 --- /dev/null +++ b/src/multisig/multisig_clsag_context.h @@ -0,0 +1,137 @@ +// Copyright (c) 2021, The Monero Project +// +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without modification, are +// permitted provided that the following conditions are met: +// +// 1. Redistributions of source code must retain the above copyright notice, this list of +// conditions and the following disclaimer. +// +// 2. Redistributions in binary form must reproduce the above copyright notice, this list +// of conditions and the following disclaimer in the documentation and/or other +// materials provided with the distribution. +// +// 3. Neither the name of the copyright holder nor the names of its contributors may be +// used to endorse or promote products derived from this software without specific +// prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY +// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL +// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF +// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +//// +// References +// - CLSAG (base signature scheme): https://eprint.iacr.org/2019/654 +// - MuSig2 (style for multisig signing): https://eprint.iacr.org/2020/1261 +/// + + +#pragma once + +#include "ringct/rctTypes.h" + +#include <vector> + + +namespace multisig { + +namespace signing { + +class CLSAG_context_t final { +private: + // is the CLSAG context initialized? + bool initialized; + // challenge components: c = H(domain-separator, {P}, {C}, C_offset, message, L, R) + rct::keyV c_params; + // indices in c_params where L and R will be + std::size_t c_params_L_offset; + std::size_t c_params_R_offset; + // musig2-style nonce combination factor components for multisig signing + // b = H(domain-separator, {P}, {C}, C_offset, message, {L_combined_alphas}, {R_combined_alphas}, I, D, {s_non_l}, l, k, n) + // - {P} = ring of one-time addresses + // - {C} = ring of amount commitments (1:1 with one-time addresses) + // - C_offset = pseudo-output commitment to offset all amount commitments with + // - message = message the CLSAG will sign + // - {L_combined_alphas} = set of summed-together public nonces from all multisig signers for this CLSAG's L component + // - {R_combined_alphas} = set of summed-together public nonces from all multisig signers for this CLSAG's R component + // - I = key image for one-time address at {P}[l] + // - D = auxiliary key image for the offsetted amount commitment '{C}[l] - C_offset' + // - {s_non_l} = fake responses for this proof + // - l = real signing index in {P} and '{C} - C_offset' + // - k = number of parallel nonces that each participant provides + // - n = number of ring members + rct::keyV b_params; + // indices in b_params where L and R 'alpha' components will be + std::size_t b_params_L_offset; + std::size_t b_params_R_offset; + // CLSAG 'concise' coefficients for {P} and '{C} - C_offset' + // mu_x = H(domain-separator, {P}, {C}, I, (1/8)*D, C_offset) + // - note: 'D' is stored in the form '(1/8)*D' in transaction data + rct::key mu_P; + rct::key mu_C; + // ring size + std::size_t n; + // aggregate key image: mu_P*I + mu_C*D + rct::geDsmp wH_l_precomp; + // aggregate ring members: mu_P*P_i + mu_C*(C_i - C_offset) + std::vector<rct::geDsmp> W_precomp; + // key image component base keys: H_p(P_i) + std::vector<rct::geDsmp> H_precomp; + // cache for later: generator 'G' in 'precomp' representation + rct::geDsmp G_precomp; + // real signing index in this CLSAG + std::size_t l; + // signature responses + rct::keyV s; + // number of signing nonces expected per signer + std::size_t num_alpha_components; +public: + CLSAG_context_t() : initialized{false} {} + + // prepare CLSAG challenge context + bool init( + const rct::keyV& P, + const rct::keyV& C_nonzero, + const rct::key& C_offset, + const rct::key& message, + const rct::key& I, + const rct::key& D, + const unsigned int l, + const rct::keyV& s, + const std::size_t num_alpha_components + ); + + // get the local signer's combined musig2-style private nonce and compute the CLSAG challenge + bool combine_alpha_and_compute_challenge( + // set of summed-together musig2-style public nonces from all multisig signers for this CLSAG's L component + const rct::keyV& total_alpha_G, + // set of summed-together musig2-style public nonces from all multisig signers for this CLSAG's R component + const rct::keyV& total_alpha_H, + // local signer's private musig2-style nonces + const rct::keyV& alpha, + // local signer's final private nonce, using musig2-style combination with factor 'b' + // alpha_combined = sum_i(b^i * alpha[i]) + rct::key& alpha_combined, + // CLSAG challenge to store in the proof + rct::key& c_0, + // final CLSAG challenge to respond to (need this to make multisig partial signatures) + rct::key& c + ); + + // getter for CLSAG 'concise' coefficients + bool get_mu( + rct::key& mu_P, + rct::key& mu_C + ) const; +}; + +} //namespace signing + +} //namespace multisig |