`sig
val current_tls : unit -> (module Netsys_crypto_types.TLS_PROVIDER)
val current_tls_opt :
unit -> (module Netsys_crypto_types.TLS_PROVIDER) option
val current_symmetric_crypto :
unit -> (module Netsys_crypto_types.SYMMETRIC_CRYPTO)
val current_digests : unit -> (module Netsys_crypto_types.DIGESTS)
val set_current_tls : (module Netsys_crypto_types.TLS_PROVIDER) -> unit
val set_current_symmetric_crypto :
(module Netsys_crypto_types.SYMMETRIC_CRYPTO) -> unit
val set_current_digests : (module Netsys_crypto_types.DIGESTS) -> unit
end`