fn check_signing(
keymaps: Vec<&PublicKeyMap>,
signed_key: &impl SignedObject<OwnedUserId, Base64PublicKeyOrDeviceId>,
required_signers: Option<&RequiredSigners<OwnedUserId, Base64PublicKeyOrDeviceId>>,
) -> Result<Option<Failure>, SignaturesUploadError>Expand description
Checks that a signature uploaded in upload_keys_signature is
cryptographically correct.
Returns a [upload_signatures::v3::Failure] if they the verification fails.