My trait looks something like this:

```
pub trait CryptoProvider {
    type CipherSuite: TlsCipherSuite;
    type SecureRandom: CryptoRngCore;
    type SignatureCurve: PrimeCurve;

    fn rng(&mut self) -> &mut Self::SecureRandom;

    fn verifier(&mut self) -> Result<&mut impl TlsVerifier<Self::CipherSuite>, crate::TlsError> {
        Err::<&mut NoVerify, _>(crate::TlsError::Unimplemented)
    }

    /// Decode and validate a private signing key from `key_der`.
    fn load_private_key(
        &self,
        _key_der: &[u8],
    ) -> Result<SecretKey<Self::SignatureCurve>, crate::TlsError> {
        Err::<SecretKey<Self::SignatureCurve>, _>(crate::TlsError::Unimplemented)
    }
}

```

But then i am getting 
```
the trait bound `<<<Provider as config::CryptoProvider>::SignatureCurve as ecdsa::elliptic_curve::Curve>::FieldBytesSize as Add>::Output: ArrayLength<u8>` is not satisfied
the trait `ArrayLength<u8>` is not implemented for `<<<Provider as config::CryptoProvider>::SignatureCurve as ecdsa::elliptic_curve::Curve>::FieldBytesSize as Add>::Output`rustcClick for full compiler diagnostic
config.rs(163, 23): required by a bound in `config::Signature`
connection.rs(543, 29): consider further restricting the associated type: `, <<<Provider as config::CryptoProvider>::SignatureCurve as ecdsa::elliptic_curve::Curve>::FieldBytesSize as Add>::Output: ArrayLength<u8>`
```