fn recover_keys_internal()

in src/envelope.rs [374:398]

• 24 lines of code
• 1 McCabe index (conditional complexity)

fn recover_keys_internal<CS: CipherSuite>(
    randomized_pwd_hasher: Hkdf<OprfHash<CS>>,
    nonce: GenericArray<u8, NonceLen>,
) -> Result<KeyPair<CS::KeGroup>, ProtocolError>
where
    <OprfHash<CS> as OutputSizeUser>::OutputSize:
        IsLess<U256> + IsLessOrEqual<<OprfHash<CS> as BlockSizeUser>::BlockSize>,
    OprfHash<CS>: Hash,
    <OprfHash<CS> as CoreProxy>::Core: ProxyHash,
    <<OprfHash<CS> as CoreProxy>::Core as BlockSizeUser>::BlockSize: IsLess<U256>,
    Le<<<OprfHash<CS> as CoreProxy>::Core as BlockSizeUser>::BlockSize, U256>: NonZero,
{
    let mut keypair_seed = GenericArray::<_, <CS::KeGroup as KeGroup>::SkLen>::default();
    randomized_pwd_hasher
        .expand(&nonce.concat(STR_PRIVATE_KEY.into()), &mut keypair_seed)
        .map_err(|_| InternalError::HkdfError)?;
    let client_static_keypair = KeyPair::<CS::KeGroup>::from_private_key_slice(
        &CS::KeGroup::serialize_sk(&CS::KeGroup::hash_to_scalar::<OprfHash<CS>>(
            &[keypair_seed.as_slice()],
            &GenericArray::from(STR_OPAQUE_DERIVE_AUTH_KEY_PAIR),
        )?),
    )?;

    Ok(client_static_keypair)
}