- 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
This header contains a static array that replaces the ecmult_context pre_g and pre_g_128 tables.
The gen_ecmult_static_pre_g program generates this header file.
This removes the ununsed `obj` directory. It also suggests in the README
to create the "coverage" files in a separate directory and adds the
coverage files to .gitignore.
readme: Improve instructions for coverage reports
f431b3f28ac95a3645ad5a6dc96b878fa30a1de3 valgrind_ctime_test: Add schnorrsig_sign (Jonas Nick)
16ffa9d97cef93f49544b016339c107882f9a1c3 schnorrsig: Add taproot test case (Jonas Nick)
8dfd53ee3fa059562483d1867815f78b9e00d947 schnorrsig: Add benchmark for sign and verify (Jonas Nick)
4e43520026f5bcd182d21f0759bac159ef47bb62 schnorrsig: Add BIP-340 compatible signing and verification (Jonas Nick)
7332d2db6b62fda851f9ed8adbfda187a875b84e schnorrsig: Add BIP-340 nonce function (Jonas Nick)
7a703fd97db0161bae07ef84513ddde6e0d27353 schnorrsig: Init empty experimental module (Jonas Nick)
eabd9bc46a31c0da6db6d88840eadbe9006447b1 Allow initializing tagged sha256 (Jonas Nick)
6fcb5b845d2832ce019d60507033f74426290768 extrakeys: Add keypair_xonly_tweak_add (Jonas Nick)
58254463f9a2e96d893157a341c9953c440fdf60 extrakeys: Add keypair struct with create, pub and pub_xonly (Jonas Nick)
f0010349b876bc6b3f0a6ec6c8bad0b12ca17b51 Separate helper functions for pubkey_create and seckey_tweak_add (Jonas Nick)
910d9c284c33b77774a9316d4524f313357d441c extrakeys: Add xonly_pubkey_tweak_add & xonly_pubkey_tweak_add_test (Jonas Nick)
176bfb1110147b5dca1834ea071acc846fb1cab3 Separate helper function for ec_pubkey_tweak_add (Jonas Nick)
4cd2ee474d178bd1b5602486104db346a7562c67 extrakeys: Add xonly_pubkey with serialize, parse and from_pubkey (Jonas Nick)
47e6618e11813cfabe91f0909ca031f960cb7dd4 extrakeys: Init empty experimental module (Jonas Nick)
3e08b02e2a78f2a1fc457efab665db8ab8085373 Make the secp256k1_declassify argument constant (Jonas Nick)
Pull request description:
This PR implements signing, verification and batch verification as described in [BIP-340](https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki) in an experimental module named `schnorrsig`. It includes the test vectors and a benchmarking tool.
This PR also adds a module `extrakeys` that allows [BIP-341](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki)-style key tweaking.
(Adding ChaCha20 as a CSPRNG and batch verification was moved to PR #760).
In order to enable the module run `./configure` with `--enable-experimental --enable-module-schnorrsig`.
Based on apoelstra's work.
ACKs for top commit:
gmaxwell:
ACK f431b3f28ac95a3645ad5a6dc96b878fa30a1de3 (exactly matches the previous post-fixup version which I have already reviewed and tested)
sipa:
ACK f431b3f28ac95a3645ad5a6dc96b878fa30a1de3
real-or-random:
ACK f431b3f28ac95a3645ad5a6dc96b878fa30a1de3 careful code review
Tree-SHA512: e15e849c7bb65cdc5d7b1d6874678e275a71e4514de9d5432ec1700de3ba92aa9f381915813f4729057af152d90eea26aabb976ed297019c5767e59cf0bbc693
Valgrind does bit-level tracking of the "uninitialized" status of memory,
property tracks memory which is tainted by any uninitialized memory, and
warns if any branch or array access depends on an uninitialized bit.
That is exactly the verification we need on secret data to test for
constant-time behaviour. All we need to do is tell valgrind our
secret key is actually uninitialized memory.
This adds a valgrind_ctime_test which is compiled if valgrind is installed:
Run it with libtool --mode=execute:
$ libtool --mode=execute valgrind ./valgrind_ctime_test
We observe that when changing the b-value in the elliptic curve formula
`y^2 = x^3 + ax + b`, the group law is unchanged. Therefore our functions
for secp256k1 will be correct if and only if they are correct when applied
to the curve defined by `y^2 = x^3 + 4` defined over the same field. This
curve has a point P of order 199.
This commit adds a test which computes the subgroup generated by P and
exhaustively checks that addition of every pair of points gives the correct
result.
Unfortunately we cannot test const-time scalar multiplication by the same
mechanism. The reason is that these ecmult functions both compute a wNAF
representation of the scalar, and this representation is tied to the order
of the group.
Testing with the incomplete version of gej_add_ge (found in 5de4c5dff^)
shows that this detects the incompleteness when adding P - 106P, which
is exactly what we expected since 106 is a cube root of 1 mod 199.
This vastly shrinks the size of the context required for signing on devices with
memory-mapped Flash.
Tables are generated by the new gen_context tool into a header.
