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VerifyingKey.from_string built the public point without the curve order, so on the Weierstrass curves precompute() failed with AssertionError for every key built from bytes, PEM or DER, the last two going through from_string. A verifying key obtained from a SigningKey, or from signature recovery, carries the order and could be precomputed. Pass the order to PointJacobi.from_bytes and test precompute() after each of the four constructions.
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@tomato42 the two workflow runs on this PR (GitHub CI and CodeQL) have been waiting for approval since I opened it, so CI has not run here yet — it is my first PR to this repo. Could you approve them? Re-checked today on the current tip |
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On the Weierstrass curves,
VerifyingKey.precompute()raisesAssertionErrorfor every key built withfrom_string,from_pemorfrom_der. On 0.19.2:precompute()SigningKey.from_secret_exponent(...).verifying_keyVerifyingKey.from_string(raw)/from_string(compressed)AssertionErrorVerifyingKey.from_pem(...)/from_der(...)AssertionErrorCause:
from_stringcallsPointJacobi.from_byteswithoutorder, sopoint.order()isNone;precompute()then hitsassert orderin_maybe_precompute.from_pemandfrom_dergo throughfrom_string. Keys from aSigningKeyor from signature recovery carry the order and are not affected; EdDSA keys take a separate branch.Fix: pass
order=curve.order(one line). Test:precompute()thenverify()after each of the four constructions; it fails on master and passes with the fix. Full suite: 2040 passed.The docstring says to call
precompute()when verifying hundreds of signatures under one key. A caller in that case usually has the key as bytes, PEM or DER, which is whereprecompute()fails. Measured on secp256k1, a verification drops from about 1057 µs to 501 µs with the table.Written with LLM, a computer and the Internet; the mistakes, as usual, are all mine.