noir-bignum-paramgen

rust tool to generate parameters for noir's noir-bignum library (https://github.com/noir-lang/noir-bignum).

The tool takes in a big integer modulus and prints out a string that represents one of the following:

1. A BigNumInstance object that can be used to statically define the field (for when the field modulus is a circuit constant)
2. A runtime_bignum::BigNumInstance object that can be used to dynamically define the field from witness values (e.g. RSA signature verification)
3. An array of Field elements that represents a BigNum object
4. An array of Field elements that represents the Barrett reduction parameter for a runtime_bignum::BigNumInstance object

When constructing parameters for static fields, the 1st case should be usd.

If formatted BigNum limbs are public/private inputs to a noir circuit, the 3rd case can be used to generate the required witness values.

If a field modulus is defined via a witness, the Barrett reduction parameter must be provided to the circuit. It is only used in unconstrained functions and can be directly supplied without deriving in-circuit. In this case option 4 should be used.

usage

cargo build --release ./target/release/paramgen [instance, runtime_instance, limbs, redc_param] [bignum modulus in hex or decimal] ?[parameter name]

The 1st input argument defines which parameter is being generated The 2nd argument defines the bignum modulus, either in base 10 or base 16 (base 16 can be prepended with 0x but does not need to be) The 3rd argument is the parameter name

example usage

./target/release/paramgen instance 0x01C4C62D92C41110229022EEE2CDADB7F997505B8FAFED5EB7E8F96C97D87307FDB925E8A0ED8D99D124D9A15AF79DB117E776F218059DB80F0DA5CB537E38685ACCE9767254A4638810719AC425F0E39D54522CDD119F5E9063DE245E8001 MNT6_753_Fr > out.txt

./target/release/paramgen runtime_instance 8444461749428370424248824938781546531375899335154063827935233455917409239041 BLS12_377_Fr > out.txt

./target/release/paramgen limbs 01C4C62D92C41110229022EEE2CDADB7F997505B8FAFED5EB7E8F96C97D87307FDB925E8A0ED8D99D124D9A15AF79DB26C5C28C859A99B3EEBCA9429212636B9DFF97634993AA4D6C381BC3F0057974EA099170FA13A4FD90776E240000001 MNT4_753_Fr > out.txt

./target/release/paramgen redc_param 0xffffffff00000001000000000000000000000000ffffffffffffffffffffffff Secp256r1_Fq > out.txt