Squashed 'src/secp256k1/' changes from 705ce7ed8c..c545fdc374

c545fdc374 Merge bitcoin-core/secp256k1#1298: Remove randomness tests
b40e2d30b7 Merge bitcoin-core/secp256k1#1378: ellswift: fix probabilistic test failure when swapping sides
c424e2fb43 ellswift: fix probabilistic test failure when swapping sides
907a67212e Merge bitcoin-core/secp256k1#1313: ci: Test on development snapshots of GCC and Clang
0f7657d59c Merge bitcoin-core/secp256k1#1366: field: Use `restrict` consistently in fe_sqrt
cc55757552 Merge bitcoin-core/secp256k1#1340: clean up in-comment Sage code (refer to secp256k1_params.sage, update to Python3)
600c5adcd5 clean up in-comment Sage code (refer to secp256k1_params.sage, update to Python3)
981e5be38c ci: Fix typo in comment
e9e9648219 ci: Reduce number of macOS tasks from 28 to 8
609093b387 ci: Add x86_64 Linux tasks for gcc and clang snapshots
1deecaaf3b ci: Install development snapshots of gcc and clang
b79ba8aa4c field: Use `restrict` consistently in fe_sqrt
c9ebca95f9 Merge bitcoin-core/secp256k1#1363: doc: minor ellswift.md updates
afd7eb4a55 Merge bitcoin-core/secp256k1#1371: Add exhaustive tests for ellswift (with create+decode roundtrip)
2792119278 Add exhaustive test for ellswift (create+decode roundtrip)
c7d900ffd1 doc: minor ellswift.md updates
332af315fc Merge bitcoin-core/secp256k1#1344: group: save normalize_weak calls in `secp256k1_ge_is_valid_var`/`secp256k1_gej_eq_x_var`
9e6d1b0e9b Merge bitcoin-core/secp256k1#1367: build: Improvements to symbol visibility logic on Windows (attempt 3)
0aacf64352 Merge bitcoin-core/secp256k1#1370: Corrected some typos
b6b9834e8d small fixes
07c0e8b82e group: remove unneeded normalize_weak in `secp256k1_gej_eq_x_var`
3fc1de5c55 Merge bitcoin-core/secp256k1#1364: Avoid `-Wmaybe-uninitialized` when compiling with `gcc -O1`
fb758fe8d6 Merge bitcoin-core/secp256k1#1323: tweak_add: fix API doc for tweak=0
c6cd2b15a0 ci: Add task for static library on Windows + CMake
020bf69a44 build: Add extensive docs on visibility issues
0196e8ade1 build: Introduce `SECP256k1_DLL_EXPORT` macro
9f1b1904a3 refactor: Replace `SECP256K1_API_VAR` with `SECP256K1_API`
ae9db95cea build: Introduce `SECP256K1_STATIC` macro for Windows users
7966aee31d Merge bitcoin-core/secp256k1#1369: ci: Print commit in Windows container
a7bec34231 ci: Print commit in Windows container
249c81eaa3 Merge bitcoin-core/secp256k1#1368: ci: Drop manual checkout of merge commit
98579e297b ci: Drop manual checkout of merge commit
5b9f37f136 ci: Add `CFLAGS: -O1` to task matrix
a6ca76cdf2 Avoid `-Wmaybe-uninitialized` when compiling with `gcc -O1`
0fa84f869d Merge bitcoin-core/secp256k1#1358: tests: introduce helper for non-zero `random_fe_test()` results
5a95a268b9 tests: introduce helper for non-zero `random_fe_test` results
304421d57b tests: refactor: remove duplicate function `random_field_element_test`
3aef6ab8e1 Merge bitcoin-core/secp256k1#1345: field: Static-assert that int args affecting magnitude are constant
4494a369b6 Merge bitcoin-core/secp256k1#1357: tests: refactor: take use of `secp256k1_ge_x_on_curve_var`
799f4eec27 Merge bitcoin-core/secp256k1#1356: ci: Adjust Docker image to Debian 12 "bookworm"
c862a9fb49 ci: Adjust Docker image to Debian 12 "bookworm"
a1782098a9 ci: Force DWARF v4 for Clang when Valgrind tests are expected
7d8d5c86df tests: refactor: take use of `secp256k1_ge_x_on_curve_var`
8a7273465b Help the compiler prove that a loop is entered
fd491ea1bb Merge bitcoin-core/secp256k1#1355: Fix a typo in the error message
ac43613d25 Merge bitcoin-core/secp256k1#1354: Add ellswift to CHANGELOG
67887ae65c Fix a typo in the error message
926dd3e962 Merge bitcoin-core/secp256k1#1295: abi: Use dllexport for mingw builds
10836832e7 Merge bitcoin-core/secp256k1#1336: Use `__shiftright128` intrinsic in `secp256k1_u128_rshift` on MSVC
7c7467ab7f Refer to ellswift.md in API docs
c32ffd8d8c Add ellswift to CHANGELOG
3c1a0fd37f Merge bitcoin-core/secp256k1#1347: field: Document return value of fe_sqrt()
5779137457 field: Document return value of fe_sqrt()
be8ff3a02a field: Static-assert that int args affecting magnitude are constant
efa76c4bf7 group: remove unneeded normalize_weak in `secp256k1_ge_is_valid_var`
5b7bf2e9d4 Use `__shiftright128` intrinsic in `secp256k1_u128_rshift` on MSVC
05873bb6b1 tweak_add: fix API doc for tweak=0
6ec3731e8c Simplify test PRNG implementation
fb5bfa4eed Add static test vector for Xoshiro256++
723e8ca8f7 Remove randomness tests
bc7c8db179 abi: Use dllexport for mingw builds

git-subtree-dir: src/secp256k1
git-subtree-split: c545fdc374964424683d9dac31a828adedabe860

doc/ellswift.md

@@ -88,7 +88,7 @@ $$
 \begin{array}{lcl}
 X(u, t) & = & \left\\{\begin{array}{ll}
   \dfrac{g(u) - t^2}{2t} & a = 0 \\
-  \dfrac{g(u) + h(u)(Y_0(u) + X_0(u)t)^2}{X_0(u)(1 + h(u)t^2)} & a \neq 0
+  \dfrac{g(u) + h(u)(Y_0(u) - X_0(u)t)^2}{X_0(u)(1 + h(u)t^2)} & a \neq 0
 \end{array}\right. \\
 Y(u, t) & = & \left\\{\begin{array}{ll}
   \dfrac{X(u, t) + t}{u \sqrt{-3}} = \dfrac{g(u) + t^2}{2tu\sqrt{-3}} & a = 0 \\
@@ -329,7 +329,7 @@ $t$ value for multiple $c$ inputs (thereby biasing that encoding):
     it requires $g(u)=0$ which is already outlawed on even-ordered curves and impossible on others; in the second it would trigger division by zero.
 * Curve-specific special cases also exist that need to be rejected, because they result in $(u,t)$ which is invalid to the decoder, or because of division by zero in the encoder:
   * For $a=0$ curves, when $u=0$ or when $t=0$. The latter can only be reached by the encoder when $g(u)=0$, which requires an even-ordered curve.
-  * For $a \neq 0$ curves, when $X_0(u)=0$, when $h(u)t^2 = -1$, or when $2w(u + 2v) = 2X_0(u)$ while also either $w \neq 2Y_0(u)$ or $h(u)=0$.
+  * For $a \neq 0$ curves, when $X_0(u)=0$, when $h(u)t^2 = -1$, or when $w(u + 2v) = 2X_0(u)$ while also either $w \neq 2Y_0(u)$ or $h(u)=0$.
 
 **Define** a version of $G_{c,u}(x)$ which deals with all these cases:
 * If $a=0$ and $u=0$, return $\bot.$