3ae7791bca refactor: use Span in random.* (pasta)
Pull request description:
~This PR does two things~
1. use a Span<unsigned char> for GetRandBytes and GetStrongRandBytes
~2. make GetRand a template for which any integral type can be used, where the default behavior is to return a random integral up to the max of the integral unless a max is provided.
This simplifies a lot of code from `GetRand(std::numeric_limits<uint64_t>::max()` -> `GetRand<uint64_t>()`~
MarcoFalke this was inspired by your comment here: https://github.com/bitcoin/bitcoin/pull/24185#issuecomment-1025514263 about using Span, so hopefully I'll be able to get this PR done and merged 😂
~Also, if requested I could revert the `GetRand(std::numeric_limits<uint64_t>::max()` -> `GetRand<uint64_t>()` related changes if it ends up causing too many conflicts~
ACKs for top commit:
laanwj:
Thank you! Code review re-ACK 3ae7791bca
Tree-SHA512: 12375a83b68b288916ba0de81cfcab4aac14389a66a36811ae850427435eb67dd55e47df9ac3ec47db4e214f4330139e548bec815fff8a3f571484ea558dca79
libsecp256k1's secp256k1_schnorrsig_sign only follows BIP340 exactly
if an aux_rand32 argument is passed. When no randomness is used
(as is the case in the current codebase here), there is no impact
on security between not providing aux_rand32 at all, or providing
an empty one. Yet, for repeatability/testability it is simpler
to always use an all-zero one.
79fd28cacb Adds verification step to Schnorr and ECDSA signing (amadeuszpawlik)
Pull request description:
As detailed in #22435, BIP340 defines that during Schnorr signing a verification should be done. This is so that potentially corrupt signage does not leak information about private keys used during the process. This is not followed today as no such verification step is being done. The same is valid for ECDSA signing functions `Sign` and `SignCompact`.
This PR adds this missing verification step to `SignSchnorr`, `Sign` and `SignCompact`.
ACKs for top commit:
sipa:
utACK 79fd28cacb
laanwj:
Code review ACK 79fd28cacb
theStack:
re-ACK 79fd28cacb
Tree-SHA512: 8fefa26caea577ae8631cc16c4e2f4cc6cfa1c7cf51d45a4a34165636ee290950617a17a19b4237c6f7a841db0e40fd5c36ad12ef43da82507c0e9fb9375ab82
As defined in BIP340, a verification step should be executed after
`secp256k1_schnorrsig_sign` to ensure that a potentially corrupted
signature isn't used; using corrupted signatures could reveal
information about the private key used. This applies to ECSDA as
well.
Additionally clears schnorr signature if signing failed.
This makes calling code less verbose and less fragile. Also, by adding
the CKey::data() member function, it is now possible to call HexStr()
with a CKey object.
This updates libsecp to the latest API. This involves a sketchy (in
my view) cast of a const pointer to a const one, but (a) it is safe
given the actual usage of this pointer, and (b) I copied it directly
from Core -- see the final (20th) commit of the corresponding PR
https://github.com/bitcoin/bitcoin/pull/22448
This introduces Taproot wallet support. I fixed all the merge conflicts
and ensured that the tests pass, but this is still using the old sighash
(before Russell/Sanket/I redid it) so is not actually production ready.
Will be fixed when we bring Elements #1002 in.
This commit updates libsecp; I didn't take the update (since I had already updated
to a more recent version of secp-zkp several commits ago) but did take Pieter's
cleanups in the rest of the codebase.
