feat: add KB8 curve

[yelhousni]

Description

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Fixes # (issue)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
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Checklist:

• I have performed a self-review of my code
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• I have made corresponding changes to the documentation
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---

Note

Medium Risk
Introduces a new curve ID and a large amount of generated finite-field code, plus changes to point (de)serialization paths; mistakes here could break compatibility or arithmetic correctness across multiple curves.

Overview
Adds support for a new KB8 curve identifier across the ecc package, including string parsing and new scalar/base field parameters.

Introduces a new ecc/kb8 package with fp wrappers over the koalabear field and a full generated fr implementation (including arch-specific assembly hooks and exponentiation chains).

Refactors marshaling in several curve packages by removing explicit G2Affine and []G2Affine encode branches (compressed and raw) and makes small generator/test updates (e.g., adds GenE4, tweaks loops/encoding checks), alongside minor generated-code cleanups (e.g., reflect.Ptr usage and wording in grumpkin marshal errors/comments).

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G2Affine encoding cases removed, breaking serialization

High Severity

The *G2Affine, []G2Affine, and *[]G2Affine cases were removed from both encode and encodeRaw across all pairing-friendly curve marshal.go files. Since G2Affine does not implement io.WriterTo, the generic interface check at the top of these functions won't handle it. Encoding any G2 point now falls through to the default case, which returns an "unsupported type" error. The decoder still has explicit *G2Affine and *[]G2Affine cases, confirming these types need explicit handling. This breaks G2 serialization in bls12-377, bls12-381, bls24-315, bls24-317, bn254, bw6-633, and bw6-761.

Additional Locations (2)

• ecc/bn254/marshal.go#L480-L548
• ecc/bls12-381/marshal.go#L515-L583

 

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