Alt-BN128
This code implements serialization and deserialization functions for a set of structs that wrap types defined in the bn module. The purpose of the Wrap* structs is to provide an implementation of the BorshSerialize and BorshDeserialize traits from the borsh crate, which enables serialization and deserialization of the corresponding types to and from binary data.
The bn module provides types for a Barreto-Naehrig elliptic curve with 128-bit security, also known as alt_bn128. Specifically, the WrapU256, WrapFr, WrapFq, WrapFq2, WrapG1, and WrapG2 structs wrap U256, Fr, Fq, Fq2, G1, and G2 types, respectively. The U256 type is a 256-bit unsigned integer, and the Fr, Fq, and Fq2 types are elements of the field used in the elliptic curve. The G1 and G2 types are points on the curve, where G1 is the group of points over the base field and G2 is the group of points over a quadratic extension of the base field.
The serialization and deserialization functions use the serialize and deserialize methods of the BorshSerialize and BorshDeserialize traits, respectively, to write and read the binary data for each wrapped type. For the WrapFr and WrapFq types, an additional check is performed to ensure that the deserialized value is less than the modulus of the field, which is required for the value to be a valid element of the field. For the WrapG1 and WrapG2 types, the serialization and deserialization functions convert the points to and from the affine representation, which is a more compact representation that only stores the x and y coordinates of the points. The AffineG1 and AffineG2 types provide the conversion functions for the G1 and G2 points, respectively.