Any easy way to verify secp256r1 (NIST P256) ECDSA signature?

[xomexh]

The custom curve params for the NIST curve does not seem to work. Anyway/any work around as to how a P256 ECDSA signature?
Using curve params as:

const secp256r1Params: CurveParams = {
   name: 'secp256r1',
   modulus: 0xFFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFFn,
   order: 0xFFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551n,
   a: -3n,
   b: 0x5AC635D8AA3A93E7B3EBBD55769886BC651D06B0CC53B0F63BCE3C3E27D2604Bn,
   generator: {
     x: 0x6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296n,
     y: 0x4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5n,
   },
};```

[Trivo25]

Hey! Unfortunately, we currently only support foreign curves with curve parameter a !== 0, and here a = -3

https://github.com/o1-labs/o1js-bindings/blob/df8c87ed6804465f79196fdff84e5147ae71e92d/crypto/elliptic-curve.ts#L531-L532

To support curves with a = 0, we would have to implement the a = 0 case in the code base

[xomexh]

Thank you for the reply, I would see I'd see for myself if I could do something about this.

Also another completely unrelated issue/doubt, is there an easy way to pass a composite struct having string data inside to a zkProgram?

This inherently doesn't give any errors, but the values of sig and msg are not accessible inside prove-able code (inside the methods of zkProgram) i.e I get no value from these fields of sig and msg.

Example:

class P256_Signature_Field extends Struct({
    sig: String,
    msg: String
}){
    constructor(value:{sig:string, msg:string}){
        super(value)
    }
}

[Trivo25]

Also another completely unrelated issue/doubt, is there an easy way to pass a composite struct having string data inside to a zkProgram?

You can't work with strings inside provable code, you would have to convert your strings into Field elements using an encoding