ac1e36769dda3964f7294319ecb06fb5c414938d musig: turn off multiexponentiation for now (Jonas Nick)
3c79d97bd92ec22cc204ff5a08c9b0e5adda12e6 ci: increase timeout for macOS tasks (Jonas Nick)
22c88815c76e6edb23baf9401f820e1a944c3ecf musig: replace MuSig(1) with MuSig2 (Jonas Nick)
Pull request description:
The main commit comprises `905 insertions(+), 1253 deletions(-)`. The diff isn't as small as I had hoped, but that's mostly because it was possible to simplify the API quite substantially which required rewriting large parts. Sorry, almost all of the changes are in one big commit which makes the diff very hard to read. Perhaps best to re-review most parts from scratch.
A few key changes:
- Obviously no commitment round. No big session struct and no `verifier` sessions. No `signer` struct.
- There's a new `secnonce` struct that is the output of musig_nonce_gen and derived from a uniformly random session_id32. The derivation can be strengthened by adding whatever session parameters (combined_pk, msg) are available. The nonce function is my ad-hoc construction that allows for these optional inputs. Please have a look at that.
- The secnonce is made invalid after being used in partial_sign.
- Adaptor signatures basically work as before, according to https://github.com/ElementsProject/scriptless-scripts/pull/24 (with the exception that they operate on aggregate instead of partial sigs)
- To avoid making this PR overly complex I did not consider how this implementation interacts with nested-MuSig, sign-to-contract, and antiklepto.
- Testing should be close to complete. There's no reachable line or branch that isn't exercised by the tests.
- [x] ~In the current implementation when a signer sends an invalid nonce (i.e. some garbage that can't be mapped to a group element), it is ignored when combining nonces. Only after receiving the signers partial signature and running `partial_sig_verify` will we notice that the signer misbehaved. The reason for this is that 1) this makes the API simpler and 2) malicious peers don't gain any additional powers because they can always interrupt the protocol by refusing to sign. However, this is up for discussion.~ EDIT: this is not the case anymore since invalid nonces are rejected when they're parsed.
- [x] ~For every partial signature we verify we have to parse the pubnonce (two compressed points), despite having parsed it in `process_nonces` already. This is not great. `process_nonces` could optionally output the array of parsed pubnonces.~ EDIT: fixed by having a dedicated type for nonces.
- [x] ~I left `src/modules/musig/musig.md` unchanged for now. Perhaps we should merge it with the `musig-spec`~ EDIT: musig.md is updated
- [x] partial verification should use multiexp to compute `R1 + b*R2 + c*P`, but this can be done in a separate PR
- [x] renaming wishlist
- pre_session -> keyagg_cache (because there is no session anymore)
- pubkey_combine, nonce_combine, partial_sig_combine -> pubkey_agg, nonce_agg, partial_sig_agg (shorter, matches terminology in musig2)
- musig_session_init -> musig_start (shorter, simpler) or [musig_generate_nonce](https://github.com/ElementsProject/secp256k1-zkp/pull/131#discussion_r654190890) or musig_prepare
- musig_partial_signature to musig_partial_sig (shorter)
- [x] perhaps remove pubnonces and n_pubnonces argument from process_nonces (and then also add a opaque type for the combined nonce?)
- [x] write the `combined_pubkey` into the `pre_session` struct (as suggested [below](https://github.com/ElementsProject/secp256k1-zkp/pull/131#issuecomment-866904975): then 1) session_init and process_nonces don't need a combined_pk argument (and there can't be mix up between tweaked and untweaked keys) and 2) pubkey_tweak doesn't need an input_pubkey and the output_pubkey can be written directly into the pre_session (reducing frustration such as Replace MuSig(1) module with MuSig2 #131 (comment))
- [x] perhaps allow adapting both partial sigs (`partial_sig` struct) and aggregate partial sigs (64 raw bytes) as suggested [below](https://github.com/ElementsProject/secp256k1-zkp/pull/131#issuecomment-867281531).
Based on #120.
ACKs for top commit:
robot-dreams:
ACK ac1e36769dda3964f7294319ecb06fb5c414938d
real-or-random:
ACK ac1e36769dda3964f7294319ecb06fb5c414938d
Tree-SHA512: 916b42811aa5c00649cfb923d2002422c338106a6936a01253ba693015a242f21f7f7b4cce60d5ab5764a129926c6fd6676977c69c9e6e0aedc51b308ac6578d
7dfceceea692c4118829c06128c41623b2373ac2 build: Remove #undef hack for ASM in the precomputation programs (Tim Ruffing)
bb36fe9be0998c81ebc9f18e122bb7617d919877 ci: Test `make precomp` (Tim Ruffing)
d94a37a20c3b5b44f1bcf60d309ffc50727e18e4 build: Remove CC_FOR_BUILD stuff (Tim Ruffing)
ad63bb4c296e6007dab22cda05fd599b20139362 build: Prebuild and distribute ecmult_gen table (Tim Ruffing)
ac49361ed0a342e01eafb1410c5b43e1214efaac prealloc: Get rid of manual memory management for prealloc contexts (Tim Ruffing)
6573c08f656f8ec305a2db801d57bfe6441e83e0 ecmult_gen: Tidy precomputed file and save space (Tim Ruffing)
5eba83f17c5aa1cf3698bb057a4b3ee35f3b6c30 ecmult_gen: Precompute tables for all values of ECMULT_GEN_PREC_BITS (Tim Ruffing)
fdb33dd1227f935ca95c7f8bd9429f42e18a870e refactor: Make PREC_BITS a parameter of ecmult_gen_build_prec_table (Tim Ruffing)
a4875e30a631d67b77b41f37fc3bf06ffb8ff11f refactor: Move default callbacks to util.h (Tim Ruffing)
4c94c55bce9e1fae8fd2e8993726c8ec74cc0f7d doc: Remove obsolete hint for valgrind stack size (Tim Ruffing)
5106226991117da78f85ca88b7ea66c2ac8fe0b3 exhaustive_tests: Fix with ecmult_gen table with custom generator (Tim Ruffing)
e1a76530db40b8aa8953717d9f984b6bdf845308 refactor: Make generator a parameter of ecmult_gen_create_prec_table (Tim Ruffing)
9ad09f6911906a1fa9af2c5540a8004e44f3ccc6 refactor: Rename program that generates static ecmult_gen table (Tim Ruffing)
8ae18f1ab3dce4c487bab75c2f0cdf4fe311b318 refactor: Rename file that contains static ecmult_gen table (Tim Ruffing)
00d2fa116ed7a8c2d049723aca8d8b6d1c49f6a8 ecmult_gen: Make code consistent with comment (Tim Ruffing)
3b0c2185eab0fe5cb910fffee4c88e134f6d3cad ecmult_gen: Simplify ecmult_gen context after making table static (Tim Ruffing)
e43ba02cfc836dba48c8c9a483e79b7589ce9ae1 refactor: Decouple table generation and ecmult_gen context (Tim Ruffing)
22dc2c0a0dc3b321e72253f492cfa8bcbf00169b ecmult_gen: Move table creation to new file and force static prec (Tim Ruffing)
Pull request description:
This resolves#893, resolves#692 (and also resolvesbitcoin/bitcoin#22854).
- [x] Extract table generation to separate function in separate file (to be used by generation script and exhaustive tests)
- [x] Tidy up
- [x] Remove code that deals with non-static tables
- [x] Make functions that need ecmult_gen not depend on signing context
- [x] Rename stuff to make it fit the new structure and consistent with how we hande verification tables (#956)
- [x] Fix exhaustive tests
- [x] Make table generation function take generator as input
- [x] Overwrite the static tables with a table with custom generator in exhaustive tests
- [x] Overhaul script that generates table files
- [x] Make table generation function take PREC_BITS as input (I have some code already, just not yet in this branch)
- [x] Change generation script to generate three tables (for all three values of ECMULT_GEN_PREC_BITS)
- [x] Ship pre-built tables
- [x] Add pregenerated table file to repo
- [x] Remove generation of table file from build process (like in #956)
- [x] Remove left-over stuff (e.g., detecting a compiler running on the build machine) from build system
- [x] Final cleanups (copyright headers, commit, messages, etc.)
- [ ] (separate PR:) Make sure link-time optimization remove corresponding static tables (and code) when no signing/verifcation function is called
- [ ] (separate PR:) Compile precomputation as a separate object file and link it (https://github.com/bitcoin-core/secp256k1/pull/988#issuecomment-977813538)
- [ ] (separate PR:) Document the backwards-compatible API changes made in this PR and in #956.
- [ ] Maybe deprecate the static context
ACKs for top commit:
sipa:
ACK 7dfceceea692c4118829c06128c41623b2373ac2
robot-dreams:
ACK 7dfceceea692c4118829c06128c41623b2373ac2 (based on range-diff between 56284c7d44c0ed46e636588bfbf6c403b7dfa6c1 and 7dfceceea692c4118829c06128c41623b2373ac2)
Tree-SHA512: 6efb3f36f05efe3b79bbd877881fe1409f71fd6488d24c811b2e77d9f053bed78670dd1dcbb42ad780458a51c4ffa36de9cd6567271b22041dc7a122ceb677c5
This was necessary because we used to cross-compile the library but
compile the precomputation programs for the build host. Now it's no
longer necessary and we can cleanly link even the external ASM
(which was the intent of #935).
On the way, remove an obsolete "-I" parameter.
- Improve Makefile.am for both prebuilt tables files
- On the way, tidy EXTRA_DIST: Move the header files to noinst_HEADERS,
where they conceptually belong, and add missing SECURITY.md to EXTRA_DIST
099bad945e9a7c5237cdd764eca420285a9de279 Comment and check a parameter for inf in secp256k1_ecmult_const. (Russell O'Connor)
6c0be857f8fee7807a2a704465d2e0f6b1f021e3 Verify that secp256k1_ge_set_gej_zinv does not operate on infinity. a->x and a->y should not be used if the infinity flag is set. (Russell O'Connor)
Pull request description:
a->x and a->y should not be used if the infinity flag is set.
ACKs for top commit:
robot-dreams:
ACK 099bad945e9a7c5237cdd764eca420285a9de279
real-or-random:
ACK 099bad945e9a7c5237cdd764eca420285a9de279 I inspected all call sites, they all ensure that a is not infinity
Tree-SHA512: 495fcfe4ec4cacb3fc64bd5d04ecc67ab34f6b63666c6169d473abfd63c2041bc501a9a60d817566517435b986406ea2b7db3f5806043cecf30e214eba9892e9
592661c22f56736099f83700be8cf280f8a963ff ci: move test environment variable declaration to .cirrus.yml (siv2r)
dcbe84b84182bb077bc8639536a778a3129b1b3e bench: add --help option to bench. (siv2r)
Pull request description:
Fixes#1005
**Changes:**
- added `--help` option to `bench.c`
- `help()` function prints the help to command-line
- `have_invalid_args()` checks if the user has entered an invalid argument
- moved `secp256k1_bench_iters` and `secp256k1_test_iters` environment variables declaration to `.cirrus.yml`
ACKs for top commit:
sipa:
utACK 592661c22f56736099f83700be8cf280f8a963ff
real-or-random:
ACK 592661c22f56736099f83700be8cf280f8a963ff
Tree-SHA512: ebc6a2e6e47b529212efa1c9b75cc79649fca7f42aa75ce46502db24ac94f46b6cef59c828d13265d1fa69187a81c140d1951e7daeb7c8e008a6c1ad75259741
The following functions were created:
1. bench.c: help()
- prints the help to the command-line
2. bench.h: have_invalid_args()
- takes a list of arguments that the user is allowed to enter on the command-line
- returns 1 if the user entered an invalid argument
- returns 0 if all the user entered arguments are valid
This is a backwards-compatible API change: Before this commit, a context
initialized for signing was required to call functions that rely on
ecmult_gen. After this commit, this is no longer necessary because the
static ecmult_gen table is always present. In practice this means that
the corresponding functions will just work instead of calling the
illegal callback when given a context which is not (officially)
initialized for signing.
This is in line with 6815761, which made the analogous change with
respect to ecmult and contexts initialized for signing. But as opposed
to 681571, which removed the ecmult context entirely, we cannot remove
the ecmult_gen context entirely because it is still used for random
blinding. Moreover, since the secp256k1_context_no_precomp context is
const and cannot meaningfully support random blinding, we refrain (for
now) from changing its API, i.e., the illegal callback will still be
called when trying to use ecmult_gen operations with the static
secp256k1_context_no_precomp context.
60bf8890df5360148df921f26d8dc4d667dd5926 ecmult: fix definition of STRAUSS_SCRATCH_OBJECTS (Jonas Nick)
Pull request description:
This bug was introduced in 7506e064d791e529d2e57bb52c156deb33b897ef by adding
an allocation but not updating the constant.
ACKs for top commit:
robot-dreams:
ACK 60bf8890df5360148df921f26d8dc4d667dd5926
real-or-random:
ACK 60bf8890df5360148df921f26d8dc4d667dd5926
Tree-SHA512: d7782fe9bf09fea8cf22304ab13679223a48f4d8b09081e662ea162a68c4e35f6b5820fbe4c6030fabad02a48dfdd02eb9eef22262c1dbbf02955bb92b75aef8
This fixes a compiler warning:
./src/ecdsa_impl.h:312:12: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical]
return !secp256k1_scalar_is_zero(sigr) & !secp256k1_scalar_is_zero(sigs);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
BIP340's default signing algorithm always requires an aux_rnd argument,
but permits using an all-zero one when no randomness is available.
Make secp256k1_schnorrsig_sign follow this even when aux_rnd32==NULL,
by treating the same as if an all-zero byte array was provided as
input.
