Silence a compiler warning about an unitialized use of a scalar in case
the user tries to provide a 0-length list of commitments.
Also ensures that commitments have normalized field elements when they
are loaded into ges.
Provides a method that will give an upper bound on the size of a rangeproof,
given an upper bound on the value to be passed in and an upper bound on the
min_bits parameter.
There is a lot of design freedom here since the actual size of the rangeproof
depends on every parameter passed to rangeproof_sign, including the value to
be proven, often in quite intricate ways. For the sake of simplicity we assume
a nonzero `min_value` and that `exp` will be 0 (the default, and size-maximizing,
choice), and provide an exact value for a proof of the given value and min_bits.
5ac8fb035e surjectionproof: make sure that n_used_pubkeys > 0 in generate (Jonas Nick)
Pull request description:
ACKs for top commit:
apoelstra:
utACK 5ac8fb035e
Tree-SHA512: 915f7181e69e2c4e1f830d6c2620a2d9b0af4d2ae8a63709b489b01ed9e13ccfeeaedebd4680cf2d927cd473a6ae88602cf29e2fdd116cb597fba6c0ab77720d
If the proof was generated with surjectionproof_initialize (as mandated by the
API docs), then n_used_pubkeys can never be 0. Without this commit, compilers
will (rightfully) warn that borromean_s[ring_input_index] is not initialized in
surjectionproof_generate. Therefore, this commit makes sure that n_used_pubkeys
is greater than 0 which ensures that the array is initialized at
ring_input_index.
Recent compilers compile the two new functions to very efficient code
on various platforms. In particular, already GCC >= 5 and clang >= 5
understand do this for the read function, which is the one critical
for performance (called 16 times per SHA256 transform).
Fixes#1080.
b8f8b99f0f docs: Fix return value for functions that don't have invalid inputs (Tim Ruffing)
f813bb0df3 schnorrsig: Adapt example to new API (Tim Ruffing)
99e6568fc6 schnorrsig: Rename schnorrsig_sign to schnorsig_sign32 and deprecate (Tim Ruffing)
fc94a2da44 Use SECP256K1_DEPRECATED for existing deprecated API functions (Tim Ruffing)
3db0560606 Add SECP256K1_DEPRECATED attribute for marking API parts as deprecated (Tim Ruffing)
Pull request description:
Should be merged before #995 if we want this.
I suspect the only change here which is debatable on a conceptual level is the renaming. I can drop this of course.
ACKs for top commit:
sipa:
utACK b8f8b99f0f
jonasnick:
ACK b8f8b99f0f
Tree-SHA512: 7c5b9715013002eecbf2e649032673204f6eaffe156f20e3ddf51fab938643847d23068f11b127ef3d7fe759e42a20ecaf2ec98718d901ef9eaadbc9853c1dfe
Also fix bug in description that resulted in a wrong definition of t.
And rename keyagg coefficient from 'mu' to 'a' since we don't use the term "musig
coefficient" anymore and a is what is used in the paper.
The vector has been taken from https://www.di-mgt.com.au/sha_testvectors.html.
It can be independently verified using the following Python code.
```
h = hashlib.sha256()
for i in range(1_000_000):
h.update(b'a')
print(h.hexdigest())
```
This avoids that the SHA256 implementation would produce wrong paddings
and thus wrong digests for messages of length >= 2^32 bytes on 32-bit
platforms.
This is not exploitable in any way since the SHA256 API is an internal
API and we never call it with that long messages.
e848c3799c Update sage files for new formulae (Peter Dettman)
d64bb5d4f3 Add fe_half tests for worst-case inputs (Peter Dettman)
4eb8b932ff Further improve doubling formula using fe_half (Peter Dettman)
557b31fac3 Doubling formula using fe_half (Pieter Wuille)
2cbb4b1a42 Run more iterations of run_field_misc (Pieter Wuille)
9cc5c257ed Add test for secp256k1_fe_half (Pieter Wuille)
925f78d55e Add _fe_half and use in _gej_add_ge (Peter Dettman)
Pull request description:
- Trades 1 _half for 3 _mul_int and 2 _normalize_weak
Gives around 2-3% faster signing and ECDH, depending on compiler/platform.
ACKs for top commit:
sipa:
utACK e848c3799c
jonasnick:
ACK e848c3799c
real-or-random:
ACK e848c3799c
Tree-SHA512: 81a6c93b3d983f1b48ec8e8b6f262ba914215045a95415147f41ee6e85296aa4d0cbbad9f370cdf475571447baad861d2cc8e0b04a71202d48959cb8a098f584
