Webs_kit.AuthenticatableAuthenticatable data.
This module defines a simple US-ASCII compatible encoding scheme to publish non-secret, expirable data bytes authenticatable via a secret private key. Human readability is a non-goal, storing your state in non-trusted environments is.
The data is not encrypted.
TODOs.
decode, are we happy about the erroring structure ?encode/decode, provide primed version which compose with {to,of}_string funs ?The type for some notion of time to expire data. For example you can use a logical notion of time or the number of seconds since the epoch.
The type for private keys. This is used with HMAC-SHA-256, so it should be at least 32 bytes long.
val random_private_key : unit -> private_keyrandom_private_key () are 64 bytes random bytes sourced after having called Stdlib.Random.self_init.
The type for authenticatable bytes. The encoding scheme for bytes data and an optional expiration timestamp expire and private key private_key is:
expire = match expire with None -> "" | Some e -> string_of_int e
msg = expire + ":" + data
authenticatable = (base64|base64url)(hmac-sha-256(private_key, msg) + msg)val encode : ?base64url:bool -> private_key:private_key -> expire:time option -> string -> tencode ~private_key ~expire data makes data data expire at expire (if any) and authenticatable via the private key private_key. If base64url is true (defaults to false) the base64url encoding scheme is used instead of base64 (see Webs.Http.Base64).
val decode : ?base64url:bool -> private_key:private_key -> now:time ->
t -> (time option * string, [ `Expired | `Decode | `Authentication ]) Stdlib.resultdecode ~key ~now s authenticates data s with the private key key and makes it expire (if applicable) according to now. The result is:
Ok (expire, data) with data authenticated by private_key and now stricly smaller than expire (if any).Error `Expired if the data could be authenticated but now is larger or equal to expire (if any).Error `Authentication if s cannot be authenticated by key.Error `Decode if any other decoding error occurs.If base64url is true (defaults to false) the base64url encoding scheme is used instead of base64.