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fix: handle constant output for sha256 #8251

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guipublic merged 1 commit into from
Aug 29, 2024
Merged

fix: handle constant output for sha256 #8251

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35 changes: 23 additions & 12 deletions barretenberg/cpp/src/barretenberg/dsl/acir_format/sha256_constraint.cpp
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
#include "sha256_constraint.hpp"
#include "barretenberg/stdlib/hash/sha256/sha256.hpp"
#include "barretenberg/stdlib/hash/sha256/sha256_plookup.hpp"
#include "msgpack/v3/unpack_decl.hpp"
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@vezenovm vezenovm Aug 28, 2024

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Suggested change
#include "msgpack/v3/unpack_decl.hpp"

why is this needed?

#include "round.hpp"

namespace acir_format {
Expand Down Expand Up @@ -39,7 +40,12 @@ template <typename Builder> void create_sha256_constraints(Builder& builder, con
auto bytes = output_bytes.bytes();

for (size_t i = 0; i < bytes.size(); ++i) {
builder.assert_equal(bytes[i].normalize().witness_index, constraint.result[i]);
auto normalised = bytes[i].normalize();
if (normalised.is_constant()) {
builder.fix_witness(constraint.result[i], normalised.get_value());
} else {
builder.assert_equal(bytes[i].normalize().witness_index, constraint.result[i]);
}
}
}

Expand Down Expand Up @@ -69,17 +75,22 @@ void create_sha256_compression_constraints(Builder& builder, const Sha256Compres
auto output_bytes = stdlib::sha256_plookup::sha256_block<Builder>(hash_inputs, inputs);

for (size_t i = 0; i < 8; ++i) {
poly_triple assert_equal{
.a = output_bytes[i].normalize().witness_index,
.b = constraint.result[i],
.c = 0,
.q_m = 0,
.q_l = 1,
.q_r = -1,
.q_o = 0,
.q_c = 0,
};
builder.create_poly_gate(assert_equal);
auto normalised_output = output_bytes[i].normalize();
if (normalised_output.is_constant()) {
builder.fix_witness(constraint.result[i], normalised_output.get_value());
} else {
poly_triple assert_equal{
.a = normalised_output.witness_index,
.b = constraint.result[i],
.c = 0,
.q_m = 0,
.q_l = 1,
.q_r = -1,
.q_o = 0,
.q_c = 0,
};
builder.create_poly_gate(assert_equal);
}
}
}

Expand Down