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Bulletproofs+ Extended generation routine (crypto::bppe_gen) adapted to match with bpp_gen

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sowle 2022-10-12 19:14:31 +02:00
parent 30972db5ad
commit 49e78fdbae
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GPG key ID: C07A24B2D89D49FC
1 changed files with 27 additions and 16 deletions
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43
src/crypto/range_proof_bppe.h
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@ -27,15 +27,17 @@ namespace crypto
#define DBG_VAL_PRINT(x) (void(0)) // std::cout << #x ": " << x << ENDL
#define DBG_PRINT(x) (void(0)) // std::cout << x << ENDL
template<typename CT>
bool bppe_gen(const scalar_vec_t& values, const scalar_vec_t& masks, const scalar_vec_t& masks2, bppe_signature& sig, std::vector<point_t>& commitments, uint8_t* p_err = nullptr)
{
#define CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(cond, err_code) \
if (!(cond)) { LOG_PRINT_RED("bppe_gen: \"" << #cond << "\" is false at " << LOCATION_SS << ENDL << "error code = " << err_code, LOG_LEVEL_3); \
if (p_err) { *p_err = err_code; } return false; }
template<typename CT>
bool bppe_gen(const scalar_vec_t& values, const scalar_vec_t& masks, const scalar_vec_t& masks2, const std::vector<const crypto::public_key*>& commitments_1div8, bppe_signature& sig, uint8_t* p_err = nullptr)
{
// Note: commitments_1div8 are supposed to be already calculated
static_assert(CT::c_bpp_n <= 255, "too big N");
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(values.size() > 0 && values.size() <= CT::c_bpp_values_max && values.size() == masks.size() && masks.size() == masks2.size(), 1);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(values.size() > 0 && values.size() <= CT::c_bpp_values_max && values.size() == masks.size() && masks.size() == masks2.size() && values.size() == commitments_1div8.size(), 1);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(masks.is_reduced() && masks2.is_reduced(), 3);
const size_t c_bpp_log2_m = constexpr_ceil_log2(values.size());
@ -43,15 +45,6 @@ namespace crypto
const size_t c_bpp_mn = c_bpp_m * CT::c_bpp_n;
const size_t c_bpp_log2_mn = c_bpp_log2_m + CT::c_bpp_log2_n;
// pre-multiply all output points by c_scalar_1div8
// in order to enforce these points to be in the prime-order subgroup (after mul by 8 in bpp_verify())
// calc commitments vector as commitments[i] = 1/8 * values[i] * G + 1/8 * masks[i] * H + 1/8 * masks2[i] * H2
commitments.resize(values.size());
for (size_t i = 0; i < values.size(); ++i)
CT::calc_pedersen_commitment_2(values[i] * c_scalar_1div8, masks[i] * c_scalar_1div8, masks2[i] * c_scalar_1div8, commitments[i]);
// s.a. BP+ paper, page 15, eq. 11
// decompose v into aL and aR:
// v = aL o (1, 2, 2^2, ..., 2^n-1), o - component-wise product aka Hadamard product
@ -86,7 +79,7 @@ namespace crypto
DBG_PRINT("initial transcript: " << e);
hash_helper_t::hs_t hsc;
CT::update_transcript(hsc, e, commitments);
CT::update_transcript(hsc, e, commitments_1div8);
// Zarcanum paper, page 33, Fig. D.3: The prover chooses alpha_1, alpha_2 and computes A = g^aL h^aR h_1^alpha_1 h_2^alpha_2
// so we calculate A0 = alpha_1 * H + alpha_2 * H_2 + SUM(aL_i * G_i) + SUM(aR_i * H_i)
@ -336,10 +329,28 @@ namespace crypto
DBG_VAL_PRINT(sig.delta_2);
return true;
#undef CHECK_AND_FAIL_WITH_ERROR_IF_FALSE
} // bppe_gen()
// convenient overload for tests
template<typename CT>
bool bppe_gen(const scalar_vec_t& values, const scalar_vec_t& masks, const scalar_vec_t& masks2, bppe_signature& sig, std::vector<point_t>& commitments_1div8_to_be_generated, uint8_t* p_err = nullptr)
{
// calc commitments vector as commitments[i] = 1/8 * values[i] * G + 1/8 * masks[i] * H + 1/8 * masks2[i] * H2
commitments_1div8_to_be_generated.resize(values.size());
std::vector<crypto::public_key> commitments_1div8(values.size());
std::vector<const crypto::public_key*> commitments_1div8_pointers(values.size());
for (size_t i = 0; i < values.size(); ++i)
{
CT::calc_pedersen_commitment_2(values[i] * c_scalar_1div8, masks[i] * c_scalar_1div8, masks2[i] * c_scalar_1div8, commitments_1div8_to_be_generated[i]);
commitments_1div8[i] = (commitments_1div8_to_be_generated[i]).to_public_key();
commitments_1div8_pointers[i] = &commitments_1div8[i];
}
return bppe_gen<CT>(values, masks, masks2, commitments_1div8_pointers, sig, p_err);
}
#undef CHECK_AND_FAIL_WITH_ERROR_IF_FALSE
struct bppe_sig_commit_ref_t
{
bppe_sig_commit_ref_t(const bppe_signature& sig, const std::vector<point_t>& commitments)
@ -347,7 +358,7 @@ namespace crypto
, commitments(commitments)
{}
const bppe_signature& sig;
const std::vector<point_t>& commitments;
const std::vector<point_t>& commitments; // assumed to be premultiplied by 1/8
};