Commit graph

58 commits

Author SHA1 Message Date
Daniel Gulotta
f76197c602
Fix handling of Lt, LtEq (#393)
Changed the middleware to only allow comparison of integers and to
use the implementation of Ord for i64.  This matches the backend
behavior.

Also fixed a separate bug where LtEqFromEntries was producing a
NotEquals statement.
2025-08-18 07:54:20 -07:00
Ahmad Afuni
1508dd6126
feat: add container update ops (#390)
* Add container update ops

* Update src/middleware/operation.rs

Co-authored-by: Eduard S. <eduardsanou@posteo.net>

* Update src/backends/plonky2/mainpod/mod.rs

Co-authored-by: Eduard S. <eduardsanou@posteo.net>

* Code review

---------

Co-authored-by: Eduard S. <eduardsanou@posteo.net>
2025-08-13 06:34:45 +10:00
656cae77e0
Add versioning features (#387)
- Add a function to calculate the hash of the `CommonCircuitData`.  The hash uniquely identify the `CommonCircuitData` used for a circuit/proof.  Serializing the struct is not enough because the polynomial identities of the custom gates are not serialized (only their parameters are); so I made a function to extract "fingerprints" of the custom gates by evaluating them over a predefined list of uniform values, and then doing a random linear combination over the results.
- Store the full verifier only circuit data of a proof in the MainPod so that we can verify pods from old circuits in new circuits and code
- Store the hash of the `CommonCircuitData` in the MainPod so that we can reject verifying old pods that use a different `CommonCircuitData` than the current one.  This has two goals
  - If the `CommonCircuitData` changes it's very likely that the verification will fail, but it will be hard to debug.  Doing this early check helps identify the origin of the verification failure as early as possible
  - There's a chance that the verification could succeed when the `CommonCircuitData` changes, and that could be dangerous because the verification will be doing different checks than the ones intended for the original proof, so we may be skipping some constraints that could lead to exploiting the system.  For this reason, whenever the common circuit data hash changes, all previous verifying keys should be discarded (that is, not included in the VDSet)
    - The fingerprint only has ~64 bits and the "random evaluation point" is fixed.  The assumption is that the pod developers are not malicious and are not changing the gates such that different gates give the same fingerprint.  With this assumption, I find it reasonable to assume that with high probability if a gate changes, its fingerprint changes as well.
- Add a github action that updates a wiki page with a table that contains: date, commit, params hash (with a link to the actual params), verifier data only circuit data hash and common circuit data hash.  This will make it easy to track when the common circuit data changes as well as track the verifier data corresponding to various versions (identified by commit)
  - The edited page is this one https://github.com/0xPARC/pod2/wiki/MainPod-circuit-info
  
Resolve https://github.com/0xPARC/pod2/issues/386

Summary of breaking changes:
- The `RecursivePod` trait has a new method `common_hash` that needs to return the result of `hash_common_data` on the `CommonCircuitData` that the circuit uses.
2025-08-08 09:33:44 -07:00
bcaef6c47a
Add table multiplexer (and use it for container, custom pred & PublicKeyOf ops) (#376)
- Extend the `Flattenable` trait to include a `size` method that returns the number of `Target`s the type requires.  This is used in the table to figure out the max length of an array that must fit all entry types.
- Move the circuit methods to precalculate hash states and do hashes started from a precomputed state to a new module
- Introduce `MuxTableTarget` which allows easy multiplexing of tables where each sub-table may have entries of different lengths.  The table access is done via hashing + unhashing automatically (via use of a generator)
- Use the `MuxTableTarget` to access merkle tree claims and custom predicate verification, which where previously in different tables and accessed with independent random accesses each
- Move the public key derivation for the PublicKeyOf operation check to the same multiplexed table.  Now we can choose how many of those operations a circuit supports.

Resolve https://github.com/0xPARC/pod2/issues/357
Resolve https://github.com/0xPARC/pod2/issues/361
2025-08-05 19:09:41 -07:00
4fa285d9fb
support longer arrays in vec_ref (#367)
Support arrays up to 256 elements (hardcoded maximum just to avoid abuse) by combining multiple random_accesses.
The index is now split into low and high parts. It's a bit more inconvenient than using a single Target but this allows avoiding bit decomposition.
2025-07-30 16:07:25 -07:00
Rob Knight
c7b39f21f0
Support SELF keyword in Podlang parser (#368)
* Support SELF keyword in Podlang parser

* Add pretty-printing for SELF
2025-07-29 17:35:48 -07:00
brian6l
5b04b2a360
New Native Operation PublicKeyOf (#355)
* wrote some initial code

* added way to input private key into circuit

* TypedValue::SecretKey hashed as 10 32-bit limbs

* Check PublicKeyOf in Frontend and Middleware

* Diff review

* PR review

* Finish utest

* Fix bounds check

* added giving secret key witness to circuit

* Test & doc improvements

* added private key comparison to circuit and added test cases

* cargo fmt

* Add frontend tests for PublicKeyOf

* Add public_key_of and hash_of to op! macro

* Add ownership check to ticket example

* Group order checking in tests

* More negative test cases at circuit level

* Cleanups after self review

* clippy fixes

* Fixes after merge.  Temporarily remove plonky2 commit hash

* Add a nullifier to the ticket test example

* Test PublicKeyOf with a real prover (not mock)

* plonky-u32 dependency

* feat: optimize operation checks

Skip the circuits that verify operation checks other than None, Copy or
NewEntry for the public statements.  This works because public
statements are created by copying private statements, so we never use
the other operation checks in those slots.

---------

Co-authored-by: Andrew Twyman <artwyman@gmail.com>
Co-authored-by: Eduard S. <eduardsanou@posteo.net>
2025-07-28 15:53:01 -07:00
Rob Knight
9f8335756c
Add Podlang pretty-printing (#353)
* Add Podlang pretty-printing

* Review feedback changes

* Formatting

* Use Display impl for printing StatementTmplArg
2025-07-25 08:43:43 -07:00
8429cd224d
Feat/disk cache (#354)
- Bump rust version to `nightly-2025-07-02` because some of the nightly features we were using have been stabilized.
- Introduce feature `disk_cache` which enables caching to disk.  Each time an artifact is retrieved from the cache it will be read and deserialized.  On a cache miss the artifact will be created, serialized and stored to disk.
- Introduce feature `mem_cache` which enables caching to memory.  All cached artifacts are kept in memory after they are created.  The mem cache implementation avoids cloning of artifacts by extending their lifetime to `'static`.  This is `unsafe` code, but I argue that this usage is safe.
- Add a `build.rs`
  - When the feature `disk_cache` is enabled, the `build.rs` will inject env variables to the process with the git commit information, which is used to index the cached artifacts
- Replace all previous cached artifacts from `LazyStatic` methods that call the cache API
- Derive `Serialize, Deserialize` for all `*Target` types so that they can be serialized for caching to disk
- Add finer level of caching: now we cache the `CircuitData` and `VerifierData` independently.  The reason for this is that `CircuitData` is a very big artifact which is not needed for verification.  So by only accessing `VerifierData` in verification we don't pay a big overhead for reading from disk and deserializing
- Add missing artifacts to the cache: like the `CircuitData` for the `MainPod` indexed by `Params`
- Add helper types to serialize and deserialize `CircuitData`, `CommonData` and `VerifierData` with the set of gates and generators used in the recursive MainPod circuit
- Tweak the ids of our custom gates so that they remain unique when their generic parameters change
- Bugfix: several tests were using the standard `vd_set` but were using MainPod circuits with non-default parameters.  This was working before because there was a bug: the MainPod circuit was reporting that the used verifier data was the standard one instead of picking the one corresponding to it's own Params.

Summary of breaking changes:
- One and only one of the features `mem_cache` or `disk_cache` need to be enabled.  By default it's `mem_cache`
  - To enable the `disk_cache` you need to disable the default features like this: `--no-default-features --features=backend_plonky2,zk,disk_cache`
- Removed `DEFAULT_PARAMS`, instead use `Params::default()`
- Removed `STANDARD_REC_MAIN_POD_CIRCUIT_DATA`, instead use `cache_get_standard_rec_main_pod_common_circuit_data`
- The library is now using `nightly-2025-07-02`.  Some rust language features are unstable in previous versions.
2025-07-24 12:15:31 +02:00
Daniel Gulotta
89dfc4e214
always replace SELF when copying statements (#345) 2025-07-22 14:56:37 -07:00
63a716ebd7
Remove unnecessary mut in PodSigner trait (#340)
The PodSigner trait was taking `&mut self` in the `sign` method, but the
signer doesn't need mutation in the Shcnorr implementation.  Remove the
`mut`.

Previously the PodProver trait was also taking `&mut self` in the
`prove` method, and we had many tests creating a `mut Prover/mut
MockProver`.  Remove all those `mut`.

Breaking change: `PodSigner` trait method `sign` replaces `&mut self` by
`&self`
2025-07-15 17:37:26 +02:00
b5e0d97cb6
remove MockSignedPod (#339)
- breaking change: Removal of MockSignedPod.  Use SignedPod instead.
- breaking change: Redefinition of numerical id for values of PodType.
2025-07-15 11:19:19 +02:00
Rob Knight
24cafde231
Assorted tweaks to support external playground crate (#322)
* Assorted tweaks to support external playground crate

* Fix schemas

* Fixed schema again

* Add ToHex for RawValue

* Add FromHex to RawValue
2025-07-02 09:27:54 -07:00
Daniel Gulotta
335100d1d7
add auto implementation of Pod::equals (#327) 2025-07-01 11:09:35 -07:00
Rob Knight
b123185ee9
Support public key literals and tidy up handling of Raw vs PodId (#319)
* Support public key literals and tidy up handling of Raw vs PodId
2025-07-01 01:34:35 -07:00
3306f360f7
make Pod trait thread-safe (#317) 2025-06-27 15:48:52 +01:00
arnaucube
e1775d8578
add eq & partial_eq for RecursivePod, Pod traits and VDSet struct (for usage from introduction-pods) (#309)
* add eq & partial_eq for VDSet (for usage from introduction-pods)

* add eq & partial_eq impls for Pod & RecursivePod traits
2025-06-24 17:41:46 +02:00
d5da9d8593
Display point in base58 (#305)
* Compress EC subgroup points before serialising

* serialize and display point in base58

* Use Display for Points

---------

Co-authored-by: Ahmad <root@ahmadafuni.com>
2025-06-24 00:18:58 +10:00
6249406cb2
Complete the verification in MainMockPod (#302)
- Update the `RecursivePod` trait to return `vd_set` instead of `vds_root`
  - A native verifier requires the entire set to reason about the circuits that have been used in the recursive tree
- Implement serialization/deserialization for `VDSet`
- Remove `DynError` and use `BackendError` instead for middleware functions that wrap or define trait functions implemented in the backend.  This is based on the fact that we will only have a single backend enabled at a time, so there's no need for a `dyn Error`
  - Move the implementations of `_verify` functions to `verify` and similarly for `_prove`
- Complete the verification of a MockMainPod: the verification of input pods was missing.  The inclusion of these input pods in the serialization was also missing.  With this change a `MockMainPod` will grow after each recursion.  This was expected from the design but was not the case because of the missing recursive native verification implementation.

* apply feedback from @arnaucube
2025-06-19 16:28:25 +02:00
arnaucube
0541817116
move pod data's deserialization to RecursivePod trait (#294), expose get_common_data (#300) 2025-06-18 11:13:29 +02:00
3c6930dfe6
Allow literals in statement templates (#287)
This PR is a continuation of the work done in #276 
- Fix PodType in MainPod (we were using `MockMain` instead of `Main`)
- Update anchored keys in statement template arguments to only support wildcards in the origin and literal keys as the key.
  - Update the pest grammar accordingly
  - Update the parser accordingly
- Rewrite the eth_dos example in a recursive manner so that we use one recursive pod for every distance increment of 1.
  - I've also used the podlang to define the eth_dos custom predicates.  Currently all predicates are in a single batch (previously `eth_friend` was in a different batch).  With #286 we could define `eth_friend` in a different batch again.
    - I was feeling a bit creative and used a format macro to pass `Value`s from rust to the podlang code.
  - The eth_dos is now written using literals.  This resolves https://github.com/0xPARC/pod2/issues/255
- Remove `StatementArg::WildcardValue` in favor of `StatementArg::Literal`.  The `WildcardValue` was just a way to have some kind of typing for values that would be used as arguments in custom predicates.  Now that we can have literals in any statement this value can be anything, so I just removed the `WildcardValue` and use `Literal` instead.  On the backend it was already the case that both cases were treated the same way (after all, `WildcardValue` and `Literal` were 4 fields in the backend).
  - Added a new type for Value: `PodId` so that we can use it for custom predicates that take a pod id to be used in a wildcard
- Add a mock vd_set that is empty for tests that don't use plonky2; this allows running those tests individually without paying for the expensive work of calculating the vd for various circuits.
- rename StatementTmplArg::WildcardValue to StatementTmplArg::Wildcard
2025-06-16 16:38:38 +02:00
Daniel Gulotta
7d0d3ad769
Allow literals in statements (#276)
Implements #229 and #261.
2025-06-13 10:27:19 -07:00
3b4edab1f5
remove NonePod and use dummy signed pods (#272)
* remove NonePod and use dummy signed pods

* apply suggestion by @arnaucube
2025-06-13 10:14:15 +02:00
Rob Knight
3ea0d5be71
Better Hash and PartialEq for Keys and AnchoredKeys (#277) 2025-06-11 04:25:08 -07:00
arnaucube
273d803ebd
Add verifier-datas tree (set) & in-circuit verification (#274)
* containers: add method to create new {Dict,Set,Array} with custom max_depth

* add vds_tree computation, update tree circuit interface

* add VDTree struct, add DEFAULT_VD_TREE, integrate it with MainPod,EmptyPod,frontend,etc.

* adapt frontend/serialization tests to new containers field (max_depth)

* adapt interfaces to allow using custom vd_tree in frontend & backend constructors

* rename VDTree to VDSet (and derivate namings too)

* containers 'new' always with param 'max_depth', use params.max_depth_mt_containers instead of the global constant MAX_DEPTH

* adapt after rebasing the branch to main latest changes

* apply review suggestions from @ed255

* use emptypod vd_mt_proofs (using vd_set as circuit input), merge the two existing set_targets methods of MainPodVerifyTarget

* document VDSet & vds_root
2025-06-11 13:08:39 +02:00
6feff2ae69
display statement/statement_tmpl as in pod lang v1 (#269)
* display statement/statement_tmpl as in pod lang v1

* fix tests
2025-06-10 15:06:57 +02:00
621f8be6b5
Implement generic serialization/deserialization (#260)
* complete general serialization

* bump default params temporarily

* disable recursion in great_boy_pod example
2025-06-10 12:17:30 +02:00
Ahmad Afuni
c66506c048
feat(backend): Use Schnorr signatures for signed PODs (#236)
* Implement non-native extension field arithmetic

* Schnorr signature verification (#221)

* Use Schnorr signatures for signed PODs

* add custom gates (#237)

* Clippy

* Formatting

* Apply suggestions from code review

Co-authored-by: Eduard S. <eduardsanou@posteo.net>

* Fix typo

* Fix tests

* Point -> PublicKey

* Remove default nnf_div implementation for clarity

* Code review & edits for clarity

* Remove suspicious mutation

* Simplify computation

* Fix division

* Fix

* Update src/backends/plonky2/primitives/ec/curve.rs

Co-authored-by: Eduard S. <eduardsanou@posteo.net>

* Update src/backends/plonky2/primitives/ec/curve.rs

Co-authored-by: Eduard S. <eduardsanou@posteo.net>

* Fixes

* Add public key to signed POD struct

* Style

* Elaborate on in-circuit field->biguint conversion

* Add missing gates

* Comments

* Add bits to biguint struct

* Comments

* Comment

---------

Co-authored-by: Daniel Gulotta <dgulotta@alum.mit.edu>
Co-authored-by: Eduard S. <eduardsanou@posteo.net>
2025-06-10 00:24:16 +10:00
88a75986b8
Integrate recursion into MainPod (#243)
* calculate MainPod id in a dynamic-friendly way

The MainPod id is now calculated with front padding and a fixed size
independent of max_public_statements so that introduction gadgets can be
verified by a MainPod while paying only for the number of statements
they use.  This is because with front padding of none-statements we can
precompute the poseidon state corresponding to absorbing all the padding
statements and only pay constraints for the non-padding statements.

The id is calculated as follows:
`id = hash(serialize(reverse(statements || none-statements)))`

* add time feature and disable timing by default

* apply suggestions from @arnaucube

* link issues in todos
2025-05-29 17:10:19 +02:00
d3fef8392e
calculate MainPod id in a dynamic-friendly way (#241)
* calculate MainPod id in a dynamic-friendly way

The MainPod id is now calculated with front padding and a fixed size
independent of max_public_statements so that introduction gadgets can be
verified by a MainPod while paying only for the number of statements
they use.  This is because with front padding of none-statements we can
precompute the poseidon state corresponding to absorbing all the padding
statements and only pay constraints for the non-padding statements.

The id is calculated as follows:
`id = hash(serialize(reverse(statements || none-statements)))`

* fix test
2025-05-23 10:12:28 +02:00
Rob Knight
de9b206852
Serialization for Plonky2 Signed and Main PODs (#234)
* WIP

* WIP

* Working serialization for both Mock and Plonky2 versions of Signed and Main Pods

* Restore useful comment about serialized_proof()

* Use plonky2 serialization for signatures and proofs

* Add schema renames for Serialized SignedPod/MainPod types

* Break out utility function for generating common circuit data

* Review feedback fixes
2025-05-19 02:22:38 -07:00
024ed8bd04
Constraints for custom predicates (#227)
* add target types for custom predicates

* simplify

* fix clippy

* fix typo

* don't use ref for NativePredicate

* fix wrong len

* precalculate CustomPredicateBatch id

* wip

* wip

* move code back

* great progress

* wip

* code complete, hopefully; missing tests

* fill aux for custom predicate op

* fix clippy warnings

* fix typos

* fix test import

* fix missing assignment in lt_mask, test custom_operation_verify_gadget

* fix mistake

* wip

* fix

* debug revert except for let entry = CustomPredicateVerifyEntryTarget

* fix batch_id calculation by fixing padding

* oops

* remove completed TODOs
2025-05-13 11:00:45 +02:00
arnaucube
29545f03fc
migrate from anyhow to thiserror (#197)
* migrate from anyhow to thiserror (#190). pending polish error msgs

* Add backtrace and compartmentalize errors

- Include backtraces in the errors we generate.  To get this we can't
  just return a literal enum, because the backtrace requires a call.
- Related to the previous point: add methods to create errors so
  we can include the backtrace conveniently without changing too much
  the syntax.  So instead of `Err(Error::KeyNotFound(key))` (literal
  enum) it will be `Err(Error::key_not_found(key))` (method call)
- Each error should be local to its scope, and each scope should
  only return its own error.
  - The merkle tree should return `TreeError` and not Error
  - The middleware should return `MiddlewareError` and not Error
- With a global Error we can't easily include backend/frontend types in
  the error fields, so declare a `BackendError` and a `FrontendError`
  and follow the pattern from the previous point
- The Pod traits should be able to return backend errors and will be
  used in the frontend; for that we change them to use trait object
  Error: `dyn std::error::Error`

* fix error

* apply suggestions from @arnaucube

* rename XError and XResult to Error and Result

* reorg signature

* make frontend custom error more ergonomic

* remove unnecessary feature

---------

Co-authored-by: Eduard S. <eduardsanou@posteo.net>
2025-04-22 15:07:04 +02:00
Daniel Gulotta
58d3c6a236
make Pod derive from Any (#205) 2025-04-22 14:06:23 +02:00
Rob Knight
bf6d8aee8b
Re-implement serialization (#201)
* Serialization tests now pass again

* Tidy up and test more edge-cases

* Use attributes rather than custom serializer for arrays

* Add JSON Schema support

* Tests for JSON Schema generation and validation

* Add comments

* Support custom predicates

* Clippy fixes

* Make deserialization/constructor functions pub(crate)
2025-04-22 04:19:20 -07:00
Ahmad Afuni
17e6c2a092
chore(frontend): make Merkle proofs optional (#198)
* Make frontend Merkle proofs optional

* Code review

* Clippy
2025-04-17 21:51:02 +10:00
c232c8dae5
Refactor frontend/middleware types (#194)
* unify fe/be NativeOp and NativePred

* remove Origin in favour of PodId

* Combine string and hash in Key

* use middleware::AnchoredKey in frontend

* merge frontend/middleware types

* refactor custom predicates

* clean up a bit

* fix middleware custom tests

* clean up

* clean up 2

* add acronyms in typos list
2025-04-16 11:59:30 +02:00
0759d6e165
Add clippy (#191)
* Organize imports

Use rustfmt to organize imports.  Resolve #162

* remove unused imports

* Fix clippy complaints

* add clippy github action

* remove comment for @arnaucube
2025-04-08 11:52:02 -07:00
24ff82dd3d
Organize imports (#188)
* Organize imports

Use rustfmt to organize imports.  Resolve #162

* remove unused imports

* cargo fmt
2025-04-07 16:19:13 -07:00
Ahmad Afuni
6528914366
chore(backend): implement more circuit op logic (#173)
* Add backend MerkleProof type

* Add eval_not_contains

* Remove print statement

* Handle some edge cases

* Add test

* Add missing ?

* Optimisation and stylistic changes

* Code review
2025-04-08 02:15:46 +10:00
arnaucube
0637f52573
add circuit to verify signatures (SignatureVerifyGadget) (#167)
* implement circuit to verify signature (proof-based signature), ie. a 1-level recursion verification

* as agreed in the call, rename Gate -> Gadget when it's not a 'gate'

* make SignatureVerifyGadget conditional on the selector input

* small naming polish

* sigverifygadget: add s computation in-circuit, connect pk,msg,s to internalproof's public_inputs

* optimize signature verify

---------

Co-authored-by: Eduard S. <eduardsanou@posteo.net>
2025-03-31 16:36:37 -07:00
arnaucube
d6033b7090
implement SignedPod (non-mock) using proof-based signatures (#160) 2025-03-25 22:17:14 +01:00
b93187c9bb
Progress on the MainPod circuit (#159)
* feat: add SignedPodVerify test

* unify circuits style

* more clear sizes

* get operation_verify test working

* be consistent with names
2025-03-21 16:53:03 +01:00
Rob Knight
9afc43675d
Serialization of Signed and Main Pods (#128) 2025-03-21 13:42:16 +00:00
2a2628ccbf
chore: simplify ToFields trait (#154) 2025-03-20 09:38:46 +01:00
arnaucube
b1689c5b37
Merkleproof verify circuit (#143)
* merkletree: add keypath circuit

* merkletree-circuit: implement proof of existence verification in-circuit

* parametrize max_depth at the tree circuit

* Constrain selectors in-circuit

* implement merketree nonexistence proof circuit, and add edgecase tests

* add non-existence proofs documentation in the mdbook, mv EMPTY->EMPTY_VALUE & NULL->EMPTY_HASH, dependency clean and public exposure methods

* review comments, some extra polishing and add a test that expects wrong proofs to fail

* Add circuit to check only merkleproofs-of-existence

With this, the merkletree_circuit module offers two different circuits:
- `MerkleProofCircuit`: allows to verify both proofs of existence and proofs
non-existence with the same circuit.
- `MerkleProofExistenceCircuit`: allows to verify proofs of existence only.

In this way, if only proofs of existence are needed,
`MerkleProofExistenceCircuit` should be used, which requires less amount
of constraints than `MerkleProofCircuit`.

* Code review

---------

Co-authored-by: Ahmad <root@ahmadafuni.com>
2025-03-18 19:34:01 +01:00
tideofwords
2864ef22d4
Implement more frontend ops (#111)
* middleware operation output statement?

* small refactor to op() on frontend

* Implement op()

* cargo fmt

* Clippy

* Code review

---------

Co-authored-by: Ahmad <root@ahmadafuni.com>
2025-03-07 21:15:01 +10:00
Ahmad Afuni
6627b46819
chore: add statement and KV metadata to frontend PODs (#117)
* Add statement and KV metadata to frontend PODs

* Code review
2025-03-07 14:35:25 +10:00
arnaucube
c92839d897
limit the number of StatementTmpl in CustomPredicate: (#101)
* limit the number of StatementTmpl in CustomPredicate:

- add constructor method for CustomPredicate
- make size checks at the CustomPredicate creation, so that once instantiated we can assume that contains valid data

This resolves #79

* Update tests to use new interface

---------

Co-authored-by: Ahmad <root@ahmadafuni.com>
2025-03-03 14:38:51 +10:00
arnaucube
423605f867
Featurize middleware types that are actually defined by the backend (#94)
At the middleware we were defining some types that actually are dependant on the
backend no matter how we define them in the middleware.

For example, we were hardcoding the `Hash` and `Value` types and their related
behaviour (eg. `.to_fields()`) to be based on the length of 4 field elements,
but that's not a choice of the middleware, and in fact this is determined by the
backend itself. On the same time, those types and related methods do not belong
to the backend, since conceptually they are part of the middleware reasoning.

The intention of this PR is not to prematurely abstract the library, but to
avoid inconsistencies where a type or parameter is defined in the middleware to
have certain carachteristic and later in the backend it gets used differently.
The idea is that those types and parameters (eg. lengths) have a single source
of truth in the code; and in the case of the "base types" (hash, value, etc)
this is determined by the backend being used under the hood, not by a choice of
the middleware parameters.

The idea with this approach, is that the frontend & middleware should not need
to import the proving library used by the backend (eg. plonky2, plonky3, etc).

As mentioned earlier, the `Hash` and `Value` types are types belonging at the
middleware, and is the middleware who reasons about them, but depending on the
backend being used, the `Hash` and `Value` types will have different sizes. So
it's the backend being used who actually defines their nature under the hood.
For example with a plonky2 backend, these types will have a length of 4 field
elements, whereas with a plonky3 backend they will have a length of 8 field
eleements.

Note that his approach does not introduce new traits or abstract code, just
makes use of rust features to define 'base types' that are being used in the
middleware.
2025-02-27 14:15:31 +01:00