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89 lines
4.6 KiB
Nim
89 lines
4.6 KiB
Nim
# this module contains the Nim wrappers for the rln library https://github.com/kilic/rln/blob/3bbec368a4adc68cd5f9bfae80b17e1bbb4ef373/src/ffi.rs
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{.push raises: [Defect].}
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import
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os,
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waku_rln_relay_types
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const libPath = "vendor/rln/target/debug/"
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when defined(Windows):
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const libName* = libPath / "rln.dll"
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elif defined(Linux):
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const libName* = libPath / "librln.so"
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elif defined(MacOsX):
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const libName* = libPath / "librln.dylib"
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# all the following procedures are Nim wrappers for the functions defined in libName
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{.push dynlib: libName, raises: [Defect].}
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## Buffer struct is taken from
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# https://github.com/celo-org/celo-threshold-bls-rs/blob/master/crates/threshold-bls-ffi/src/ffi.rs
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type Buffer* = object
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`ptr`*: ptr uint8
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len*: uint
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#------------------------------ Merkle Tree operations -----------------------------------------
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proc update_next_member*(ctx: RLN[Bn256],
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input_buffer: ptr Buffer): bool {.importc: "update_next_member".}
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## input_buffer points to the id commitment byte seq
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## the return bool value indicates the success or failure of the operation
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proc delete_member*(ctx: RLN[Bn256], index: uint): bool {.importc: "delete_member".}
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## index is the position of the id commitment key to be deleted from the tree
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## the deleted id commitment key is replaced with a zero leaf
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## the return bool value indicates the success or failure of the operation
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proc get_root*(ctx: RLN[Bn256], output_buffer: ptr Buffer): bool {.importc: "get_root".}
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## get_root populates the passed pointer output_buffer with the current tree root
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## the output_buffer holds the Merkle tree root of size 32 bytes
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## the return bool value indicates the success or failure of the operation
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##
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#----------------------------------------------------------------------------------------------
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#-------------------------------- zkSNARKs operations -----------------------------------------
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proc key_gen*(ctx: RLN[Bn256], keypair_buffer: ptr Buffer): bool {.importc: "key_gen".}
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## generates id key and id commitment key serialized inside keypair_buffer as | id_key <32 bytes>| id_commitment_key <32 bytes> |
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## id commitment is the poseidon hash of the id key
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## the return bool value indicates the success or failure of the operation
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proc generate_proof*(ctx: RLN[Bn256],
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input_buffer: ptr Buffer,
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output_buffer: ptr Buffer): bool {.importc: "generate_proof".}
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## input_buffer serialized as [ id_key<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
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## output_buffer holds the proof data and should be parsed as |proof<256>|root<32>|epoch<32>|share_x<32>|share_y<32>|nullifier<32>|
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## integers wrapped in <> indicate value sizes in bytes
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## the return bool value indicates the success or failure of the operation
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##
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proc verify*(ctx: RLN[Bn256],
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proof_buffer: ptr Buffer,
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result_ptr: ptr uint32): bool {.importc: "verify".}
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## proof_buffer [ proof<256>| root<32>| epoch<32>| share_x<32>| share_y<32>| nullifier<32> | signal_len<8> | signal<var> ]
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## the return bool value indicates the success or failure of the call to the verify function
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## the result of the verification of the zk proof is stored in the value pointed by result_ptr, where 0 indicates success and 1 is failure
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#----------------------------------------------------------------------------------------------
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#-------------------------------- Common procedures -------------------------------------------
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proc new_circuit_from_params*(merkle_depth: uint,
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parameters_buffer: ptr Buffer,
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ctx: ptr RLN[Bn256]): bool {.importc: "new_circuit_from_params".}
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## creates an instance of rln object as defined by the rln lib https://github.com/kilic/rln/blob/7ac74183f8b69b399e3bc96c1ae8ab61c026dc43/src/public.rs#L48
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## merkle_depth represent the depth of the Merkle tree
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## parameters_buffer holds prover and verifier keys
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## ctx holds the final created rln object
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## the return bool value indicates the success or failure of the operation
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proc hash*(ctx: RLN[Bn256],
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inputs_buffer: ptr Buffer,
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output_buffer: ptr Buffer): bool {.importc: "signal_to_field".}
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## as explained in https://github.com/kilic/rln/blob/7ac74183f8b69b399e3bc96c1ae8ab61c026dc43/src/public.rs#L135, it hashes (sha256) the plain text supplied in inputs_buffer and then maps it to a field element
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## this proc is used to map arbitrary signals to field element for the sake of proof generation
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## inputs_buffer holds the hash input as a byte seq
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## the hash output is generated and populated inside output_buffer
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## the output_buffer contains 32 bytes hash output
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{.pop.}
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