Additional sighash cache index bit - #1581
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utACK 0a0dd9b FWIW I think you could change the size of the |
…PROOF keying Backport of bitcoin/bitcoin#32473 as integrated on elements-23.x (eb64d24), reapplied against master's tree. The SIGHASH_RANGEPROOF (0x40) bit changes the sighash preimage: segwit v0 appends hashRangeproofs, and the legacy serializer appends each output's rangeproof and surjectionproof. It is therefore part of the cache key, and the table has 16 entries rather than upstream's 6. Dropping that term is a consensus split with deployed elements-23.x in both directions. Upstream added SigHashCache as a pure addition, so a merge of this file will auto-merge without prompting for the Elements adaptation. Hence the explicit markers.
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apoelstra
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| // because no input can simultaneously use both. | ||
| // ELEMENTS: SIGHASH_RANGEPROOF changes the preimage (segwit v0 appends hashRangeproofs; the | ||
| // legacy serializer appends each output's rangeproof and surjectionproof), so it must be a | ||
| // dimension of the cache key. Removing this term is a consensus split with elements-23.x. |
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In 903be1e:
This comment is a bit confusing. Removing this term would break the caching logic, but it wouldn't be a "consensus split with elements 23" in particular. It'd just be wrong.
apoelstra
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Aug 13, 2026
| * optionally store a scriptCode which the hash is for, plus a midstate for the SHA256 | ||
| * computation just before adding the hash_type itself. */ | ||
| // ELEMENTS: the SIGHASH_RANGEPROOF (0x40) bit changes the sighash preimage, so it is part of | ||
| // the cache key and the table has 16 entries rather than upstream's 6. Do not drop this when |
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In 903be1e:
Fine to leave as-is, but the old table had 6 elements and we're adding 8 to it, so 14 is the correct number.
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Yes, you are right. I will leave as is though, as it is (again incorrectly) 16 in 23.x.
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Additional cache index bit added for sighash combination with SIGHASH_RANGEPROOF