- Instead of defining a synthetic q_S3 based on a combination of
of q_S1, q_S2, we simply create another selector q_S3.
- Instead of using fixed_y_q as a nonbinary selector, replace it
with q_S4 and copy the fixed value into a row above.
Co-authored-by: Daira Hopwood <daira@jacaranda.org>
The Sinsemilla chip witnesses message pieces in individual regions, and
then copies them into the `hash_piece` region to initialize the running
sum. Previously these occured in the same column, but we can reduce the
utilized rows of the Action circuit by moving these into a less-used
column.
If https://github.com/zcash/halo2/issues/334 is implemented, this change
would be unnecessary, as the witnessed message piece regions would never
be assigned into the circuit.
We were configuring multiple instances of this across all of the advice
columns, in order to spread their assignments. However, we are actually
more constrained by columns than rows, and we have comparatively few
rows of range check logic required for the Action circuit.
We now use a single LookupRangeCheckConfig for the entire circuit. The
reduction in lookup arguments and fixed columns cuts the proof size in
half (now at 6048 bytes when using `floor_planner::V1`).
Co-authored-by: therealyingtong <yingtong@z.cash>
- Move Poseidon into the right-hand advice columns. The Action circuit
has 33 Sinsemilla invocations with 510-bit inputs (the 32 Merkle path
hashes, and Commit^ivk). Poseidon fits within the row count of one of
these invocations, so we can run it in parallel with these.
- Share fixed columns between ECC and Poseidon chips. Poseidon requires
four advice columns, while ECC incomplete addition requires six, so we
could choose to configure them in parallel. However, we only use a
single Poseidon invocation, and we have the rows to accomodate it
serially with fixed-base scalar mul. Sharing the ECC chip's 8 Lagrange
coefficient fixed columns instead reduces the proof size.
- We position Poseidon in the right-most 6 fixed columns, anticipating
a further optimisation to Sinsemilla that will occupy the left-most
2 fixed columns.
The Action Circuit configuration uses 10 advice columns. It contains:
- a single EccConfig (10 advice columns);
- two SinsemillaConfigs (5 advice columns each);
- two MerkleConfigs (5 advice columns each);
- a PoseidonConfig, (4 advice columns);
- a PLONKConfig for standard PLONK operations (3 advice columns);
and some infrastructure to handle public inputs (subject to change
at the time of commit).
The 5-column configs are placed side-by-side in the circuit to
optimize space usage.
Gate creation is delegated to the configure() function of each
respective Chip.
The Default Circuit sets all fields to None. This is used as a
placeholder in src/builder.rs.
The circuit in the Circuit::round_trip() test has been filled in.
This was previously creating an extra advice column. Instead, we
should pass in all required advice columns as inputs.
Co-authored-by: Jack Grigg <jack@electriccoin.co>
- `halo2::plonk::{create_proof, verify_proof}` now take instance columns
as slices of values.
- `halo2::plonk::Permutation` has been replaced by a global permutation,
to which columns can be added with `ConstraintSystem::enable_equality`.
- The introduction of blinding rows means that various tests now require
larger circuit parameters.
The coordinate check for an element decomposed using a running sum
is enforced by mul_fixed::Config::running_sum_coords_gate().
Co-authored-by: Jack Grigg <jack@electriccoin.co>
Selectors previously used in the witness_scalar_* APIs, such as
q_scalar_fixed and q_scalar_fixed_short, are now removed. The
remaining selectors have been renamed for clarity.
The coordinates check for scalars decomposed using a running sum
has been moved into the mul_fixed.rs file, instead of being
duplicated in both mul_fixed::base_field_elem and mul_fixed::short.
The decompose_scalar_fixed() method is now only used in
mul_fixed::full_width, and has been moved there.
These are now provided as inputs to the witness_decompose() and
copy_decompose() methods. This allows us to reuse the same config
for different word/window lengths, avoiding a duplicate constraint
creation.
Co-authored-by: Jack Grigg <jack@electriccoin.co>
In the Orchard protocol, only the NullifierK fixed base in used in
scalar multiplication with a base field element.
The mul_fixed_base_field_elem() API does not have to accept fixed
bases other than NullifierK; conversely, NullifierK does not have
to work with the full-width mul_fixed() API.
therealyingtong
Jack Grigg
Kris Nuttycombe