Avoiding zero in bach muls #905
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codygunton
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We systematize the work of #4751 to avoid scalar multiplication by 0, an issue that has arisen in various ways. In our case, the acir test `6_array` was reliably failing (failing the with `Trying to invert zero in the field`) about 1/256 of the time. The error was thrown from https://github.com/AztecProtocol/aztec-packages/blob/394a0e06928946c1c9eea1bdfec39269cb2d601a/barretenberg/cpp/src/barretenberg/ecc/groups/element_impl.hpp#L68 coming from this line in Zerormorph verification https://github.com/AztecProtocol/aztec-packages/blob/394a0e06928946c1c9eea1bdfec39269cb2d601a/barretenberg/cpp/src/barretenberg/commitment_schemes/zeromorph/zeromorph.hpp#L622 Spawning an issue to handle this situation more systmatically: AztecProtocol/barretenberg#905 The PR allowed the acir test to be run more than 512 times without any issue.
AztecBot
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Mar 14, 2024
We systematize the work of AztecProtocol/aztec-packages#4751 to avoid scalar multiplication by 0, an issue that has arisen in various ways. In our case, the acir test `6_array` was reliably failing (failing the with `Trying to invert zero in the field`) about 1/256 of the time. The error was thrown from https://github.com/AztecProtocol/aztec-packages/blob/394a0e06928946c1c9eea1bdfec39269cb2d601a/barretenberg/cpp/src/barretenberg/ecc/groups/element_impl.hpp#L68 coming from this line in Zerormorph verification https://github.com/AztecProtocol/aztec-packages/blob/394a0e06928946c1c9eea1bdfec39269cb2d601a/barretenberg/cpp/src/barretenberg/commitment_schemes/zeromorph/zeromorph.hpp#L622 Spawning an issue to handle this situation more systmatically: #905 The PR allowed the acir test to be run more than 512 times without any issue.
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As in the case of AztecProtocol/aztec-packages#5174, we sometimes encounter issues relating to our inability to handle scalar multiplication of EC points in the case where the scalar is 0. I believe: this could be fixed by simply checking whether
z==0before https://github.com/AztecProtocol/aztec-packages/blob/394a0e06928946c1c9eea1bdfec39269cb2d601a/barretenberg/cpp/src/barretenberg/ecc/groups/element_impl.hpp#L68, but we avoid this because of the cost of the check. Someone should determine whether this is really a concern, and if it is, we should identify some hot code paths and use a more robust method outside of those cases.The text was updated successfully, but these errors were encountered: