c9a70f9338 script: qa: Improve Key::Fingerprint type safety (David Gumberg)
Pull request description:
Extracted from pseudoramdom's work in #35436:
Instead of using c style arrays for key fingerprints, use `std::array`'s whose length can always reasoned about at compile time and for most operations the compiler enforces the size being correct.
```cpp
using KeyFingerprint = std::array<unsigned char, 4>;
```
```diff
- unsigned char vchFingerprint[4];
+ KeyFingerprint fingerprint;
```
This allows the replacement of a lot of raw `memcpy` + trust-me-bro lengths, with the assignment operator:
```cpp
- memcpy(ret.vchFingerprint, vchFingerprint, 4);
+ ret.fingerprint = fingerprint;
```
This commit also adds two helper functions for
- Retrieving the [fingerprint of a key identifier](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#user-content-Key_identifiers) (`CKeyID`)
- Retrieving the fingerprint of the key identifier of an XPUB.
ACKs for top commit:
w0xlt:
ACK c9a70f9338
sedited:
ACK c9a70f9338
pseudoramdom:
Code review ACK w/ some minor nits c9a70f9338
polespinasa:
ACK c9a70f9338
Tree-SHA512: 3ee76742c0bc317dfbc12a6731afdcc40495db6e4d5d94880d0a721990d36cb3e4d374ccc96079ba1f8ad3f88581ee5a609bfe259c0ea7cd28cade373aac1b38
BIP32 specifies that seed must be between 128 and 512 bits
(16 to 64 bytes). CExtKey::SetSeed currently accepts any length,
including empty seeds, which could lead to weak master keys.
Add an Assert at the start of SetSeed to enforce the valid seed
length range.
Fixes#35308
Compared to `CreateMuSig2Nonce`, creating a partial signature
has a stronger link to the secret key used, but for consistency
reasons it still makes sense to move all functionality that call
the secp256k1 musig API functions to the `musig.{h,cpp}` module
for consistency.
Can be reviewed via the git option `--color-moved=dimmed-zebra`.
Nonce creation is mainly derived by randomness, and the secret
key merely serves as (optional) additional data for increasing
misuse-resistance, rather than being a central part that would
justify an own CKey method, so move it to the musig.cpp module.
Can be reviewed via the git option `--color-moved=dimmed-zebra`.
ac599c4a9c test: Test MuSig2 in the wallet (Ava Chow)
68ef954c4c wallet: Keep secnonces in DescriptorScriptPubKeyMan (Ava Chow)
4a273edda0 sign: Create MuSig2 signatures for known MuSig2 aggregate keys (Ava Chow)
258db93889 sign: Add CreateMuSig2AggregateSig (Ava Chow)
bf69442b3f sign: Add CreateMuSig2PartialSig (Ava Chow)
512b17fc56 sign: Add CreateMuSig2Nonce (Ava Chow)
82ea67c607 musig: Add MuSig2AggregatePubkeys variant that validates the aggregate (Ava Chow)
d99a081679 psbt: MuSig2 data in Fill/FromSignatureData (Ava Chow)
4d8b4f5336 signingprovider: Add musig2 secnonces (Ava Chow)
c06a1dc86f Add MuSig2SecNonce class for secure allocation of musig nonces (Ava Chow)
9baff05e49 sign: Include taproot output key's KeyOriginInfo in sigdata (Ava Chow)
4b24bfeab9 pubkey: Return tweaks from BIP32 derivation (Ava Chow)
f14876213a musig: Move synthetic xpub construction to its own function (Ava Chow)
fb8720f1e0 sign: Refactor Schnorr sighash computation out of CreateSchnorrSig (Ava Chow)
a4cfddda64 tests: Clarify why musig derivation adds a pubkey and xpub (Ava Chow)
39a63bf2e7 descriptors: Add a doxygen comment for has_hardened output_parameter (Ava Chow)
2320184d0e descriptors: Fix meaning of any_key_parsed (Ava Chow)
Pull request description:
This PR implements MuSig2 signing so that the wallet can receive and spend from imported `musig(0` descriptors.
The libsecp musig module is enabled so that it can be used for all of the MuSig2 cryptography.
Secnonces are handled in a separate class which holds the libsecp secnonce object in a `secure_unique_ptr`. Since secnonces must not be used, this class has no serialization and will only live in memory. A restart of the software will require a restart of the MuSig2 signing process.
ACKs for top commit:
fjahr:
tACK ac599c4a9c
rkrux:
lgtm tACK ac599c4a9c
theStack:
Code-review ACK ac599c4a9c🗝️
Tree-SHA512: 626b9adc42ed2403e2f4405321eb9ce009a829c07d968e95ab288fe4940b195b0af35ca279a4a7fa51af76e55382bad6f63a23bca14a84140559b3c667e7041e
The dynamically created signing context for libsecp256k1 calls is only
needed for functions that involve generator point multiplication with a
secret key, i.e. different variants of public key creation and signing.
The API docs hint to this by stating "not secp256k1_context_static" for
the context parameter. In our case that applies to the following calls:
- `secp256k1_ec_pubkey_create`
- `secp256k1_keypair_create`
- `secp256k1_ellswift_create`
- `secp256k1_ecdsa_sign`
- `secp256k1_ecdsa_sign_recoverable`
- `secp256k1_schnorrsig_sign32`
- `ec_seckey_export_der` (not a direct secp256k1 function, but calls
`secp256k1_ec_pubkey_create` inside)
For all the other secp256k1 calls we can simply use the static context.
Historically, the headers have been bumped some time after a file has
been touched. Do it now to avoid having to touch them again in the
future for that reason.
-BEGIN VERIFY SCRIPT-
sed -i --regexp-extended 's;( 20[0-2][0-9])(-20[0-2][0-9])? The Bitcoin Core developers;\1-present The Bitcoin Core developers;g' $( git show --pretty="" --name-only HEAD~1 )
-END VERIFY SCRIPT-
Replace early returns in KeyPair::KeyPair() with asserts.
The if statements imply there is an error we are handling, but keypair_xonly_pub
and xonly_pubkey_serialize can only fail if the keypair object is malformed, i.e.,
it was created with a bad secret key. Since we check that the keypair was created
successfully before attempting to extract the public key, using asserts more
accurately documents what we expect here and removes untested branches from the code.
Move `SignSchnorr` to `KeyPair`. This makes `CKey::SignSchnorr` now
compute a `KeyPair` object and then call `KeyPair::SignSchorr`. The
notable changes are:
* Move the merkle_root tweaking out of the sign function and into
the KeyPair constructor
* Remove the temporary secp256k1_keypair object and have the
functions access m_keypair->data() directly
Add a `KeyPair` class which wraps the `secp256k1_keypair`. This keeps
the secret data in secure memory and enables passing the
`KeyPair` object directly to libsecp256k1 functions expecting a
`secp256k1_keypair`.
Motivation: when passing `CKeys` for taproot outputs to libsecp256k1 functions,
the first step is to create a `secp256k1_keypair` data type and use that
instead. This is so the libsecp256k1 function can determine if the key
needs to be negated, e.g., when signing.
This is a bit clunky in that it creates an extra step when using a `CKey`
for a taproot output and also involves copying the secret data into a
temporary object, which the caller must then take care to cleanse. In
addition, the logic for applying the merkle_root tweak currently
only exists in the `SignSchnorr` function.
In a later commit, we will add the merkle_root tweaking logic to this
function, which will make the merkle_root logic reusable outside of
signing by using the `KeyPair` class directly.
Co-authored-by: Cory Fields <cory-nospam-@coryfields.com>
This method was introduced as a pre-requirement for the v2 transport
protocol back then (see PR #14047, commit 463921bb), when it was still
BIP151. With the replacement BIP324, this is not needed anymore, and
it's also unlikely that any other proposal would need to negate private
keys at this abstraction level.
(If there is really demand, it's trivial to reintroduce the method.)
Making the `GenerateRandomKey` helper available to other modules via
key.{h.cpp} allows us to create random private keys directly at
instantiation of CKey, in contrast to the two-step process of creating
the instance and then having to call `MakeNewKey(...)`.
Instead of storing the key material as an std::vector (with secure allocator),
use a secure_unique_ptr to a 32-byte array, and use nullptr for invalid keys.
This means a smaller CKey type, and no secure/dynamic memory usage for invalid
keys.
2022917223 Add secp256k1_selftest call (Pieter Wuille)
3bfca788b0 Remove explicit enabling of default modules (Pieter Wuille)
4462cb0498 Adapt to libsecp256k1 API changes (Pieter Wuille)
9d47e7b71b Squashed 'src/secp256k1/' changes from 44c2452fd3..21ffe4b22a (Pieter Wuille)
Pull request description:
Now that libsecp256k1 has a release (https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-December/021271.html), update the subtree to match it.
The changes themselves are not very impactful for Bitcoin Core, but include:
* It's no longer needed to specify whether contexts are for signing or verification or both (all contexts support everything), so make use of that in this PR.
* Verification operations can use the static context now, removing the need for some infrastructure in pubkey.cpp to make sure a context exists.
* Most modules are now enabled by default, so we can drop explicit enabling for them.
* CI improvements (in particular, MSVC and more recent MacOS)
* Introduction of an internal int128 type, which has no effect for GCC/Clang builds, but enables 128-bit multiplication in MSVC, giving a ~20% speedup there (but still slower than GCC/Clang).
* Release process changes (process documentation, changelog, ...).
ACKs for top commit:
Sjors:
ACK 2022917223, but 4462cb0498 could use more eyes on it.
achow101:
ACK 2022917223
jonasnick:
utACK 2022917223
Tree-SHA512: 8a9fe28852abe74abd6f96fef16a94d5a427b1d99bff4caab1699014d24698aab9b966a5364a46ed1001c07a7c1d825154ed4e6557c7decce952b77330a8616b
* Use SECP256K1_CONTEXT_NONE when creating signing context, as
SECP256K1_CONTEXT_SIGN is deprecated and unnecessary.
* Use secp256k1_static_context where applicable.
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.
