pub fn process_envelope_seed<'a>(
envelope_seed: EnvelopeSeed,
message_vault_id: &'a MessageVaultId,
shared_public_keys: &SharedPublicKeys,
salts: &Salts,
csprng: &mut impl CryptoRngCore,
) -> Result<(SealedEnvelopeId, Vec<(BlindedPublicKey, OneSix)>, Envelope, &'a MessageVaultId), CryptError>