btcec: Avoid panic in fieldVal.SetByteSlice for large inputs #1602
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davecgh
reviewed
Jul 12, 2020
davecgh
approved these changes
Jul 12, 2020
davecgh
requested changes
Jul 12, 2020
The implementation has been adapted from the dcrec module in dcrd. The bug was initially fixed in decred/dcrd@3d9cda1 while transitioning to a constant time algorithm. A large set of test vectors were subsequently added in decred/dcrd@8c6b52d. The function signature has been preserved for backwards compatibility. This means that returning whether the value has overflowed, and the corresponding test vectors have not been backported. This fixes btcsuite#1170 and closes a previous attempt to fix the bug in btcsuite#1178.
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Summary
The implementation has been adapted from the dcrec module in dcrd. The bug was initially fixed in decred/dcrd@3d9cda1 while transitioning to a constant time algorithm. A large set of test vectors were subsequently added in decred/dcrd@8c6b52d.
The function signature has been preserved for backwards compatibility. This means that returning whether the value has overflowed, and the corresponding test vectors have not been backported.
This fixes #1170 and closes a previous attempt to fix the bug in #1178.
Benchmarks
With changes from #1178:
With this PR: (~2.8 times faster)