…ollow-ups

57cc136 crypto: make ChaCha20::SetKey wipe buffer (Pieter Wuille)
da0ec62 tests: miscellaneous hex / std::byte improvements (Pieter Wuille)
bdcbc85 fuzz: support std::byte in Consume{Fixed,Variable}LengthByteVector (Pieter Wuille)
7d1cd93 crypto: require key on ChaCha20 initialization (Pieter Wuille)
44c1176 random: simplify FastRandomContext::randbytes using fillrand (Pieter Wuille)
3da636e crypto: refactor ChaCha20 classes to use Span<std::byte> interface (Pieter Wuille)

Pull request description:

  This modernizes the ChaCha20 and ChaCha20Aligned interfaces to be `Span<std::byte>` based, and other improvements.

  * Modifies all functions and constructors of `ChaCha20` and `ChaCha20Aligned` to be `Span<std::byte>` based (aligning them with `FSChaCha20`, `AEADChaCha20Poly1305`, and `FSChaCha20Poly1305`)
  * Remove default constructors, to make sure all call sites provide a key (suggested in bitcoin#26153 (comment))
  * Wipe key material on rekey for security (suggested in bitcoin#26153 (comment))
  * Use `HexStr` on byte vectors in tests (suggested in bitcoin#27993 (comment))
  * Support `std::byte` vectors in `ConsumeRandomLengthByteVector` and `ConsumeFixedLengthByteVector`, and use it (suggested in bitcoin#27993 (comment))
  * And a few more.

  While related, I don't see this as a necessary for BIP324.

ACKs for top commit:
  stratospher:
    ACK 57cc136.
  theStack:
    re-ACK 57cc136

Tree-SHA512: 361da4ff003c8465a32eeac0983a8a6f047dbbf5b400168b409c8e3234e79d577fc854e0764389446585da3e12b964c94dd67fc0c9c1d1d092cec296121e05d4

, bitcoin#28267, bitcoin#28374, bitcoin#28100 (p2p primitives)

b60c493 merge bitcoin#28100: more Span<std::byte> modernization & follow-ups (Kittywhiskers Van Gogh)
c2aa01c merge bitcoin#28374: python cryptography required for BIP 324 functional tests (Kittywhiskers Van Gogh)
7c5edf7 merge bitcoin#28267: BIP324 ciphersuite follow-up (Kittywhiskers Van Gogh)
1b1924e merge bitcoin#28008: BIP324 ciphersuite (Kittywhiskers Van Gogh)
ff54219 merge bitcoin#27993: Make poly1305 support incremental computation + modernize (Kittywhiskers Van Gogh)
d7482eb merge bitcoin#27985: Add support for RFC8439 variant of ChaCha20 (Kittywhiskers Van Gogh)

Pull request description:

  ## Additional Information

  * Dependent on #5900

  * Dependent on #5901

  * Without modifications, tests introduced in [bitcoin#28008](bitcoin#28008) will fail due to salt comprising of a fixed string (`bitcoin_v2_shared_secret`) and network bytes ([source](https://github.com/sipa/bitcoin/blob/1c7582ead6e1119899922041c1af2b4169b0bc74/src/bip324.cpp#L39-L40)). Bitcoin uses [`{0xf9, 0xbe, 0xb4, 0xd9}`](https://github.com/sipa/bitcoin/blob/1c7582ead6e1119899922041c1af2b4169b0bc74/src/kernel/chainparams.cpp#L114-L117) for mainnet while Dash uses [`{0xbf, 0x0c, 0x6b, 0xbd}`](https://github.com/dashpay/dash/blob/37f43e4e56de0d510110a7f790df34ea77748dc9/src/chainparams.cpp#L238-L241).
    * The replacement parameters are generated by:
      * Cloning https://github.com/bitcoin/bips (as of this writing, at bitcoin/bips@b3701fa)
      * Editing `bip-0324/reference.py`
        * Changing `NETWORK_MAGIC` to Dash's network magic
      * Running `gen_test_vectors.py` to get a new `packet_encoding_test_vectors.csv`
      * Using [this python script](https://github.com/bitcoin/bitcoin/blob/1c7582ead6e1119899922041c1af2b4169b0bc74/src/test/bip324_tests.cpp#L174-L196) mentioned in a comment in `src/test/bip324_tests.cpp`, generate the values that will be used to replace the ones in `bip324_tests.cpp` (it will print to `stdout` so it's recommended to pipe it to a file)
      * Paste the new values over the old ones

  ## Breaking Changes

  None. Changes are restricted to BIP324 cryptosuite, tests and associated logic.

  ## Checklist:
    _Go over all the following points, and put an `x` in all the boxes that apply._
  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas **(note: N/A)**
  - [x] I have added or updated relevant unit/integration/functional/e2e tests **(note: N/A)**
  - [x] I have made corresponding changes to the documentation **(note: N/A)**
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

Top commit has no ACKs.

Tree-SHA512: bb056de8588026adae63e78d56878274ff3934a439e2eae81606fa9c0a37dab432a129315bb9c1b754400b5c883bf460eea3a0c857a3be0816c8fbf55c479843