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;; This file is part of eris-cl.
;; Copyright (C) 2022 Piotr Szarmański
;; eris-cl is free software: you can redistribute it and/or modify it under the
;; terms of the GNU Lesser General Public License as published by the Free
;; Software Foundation, either version 3 of the License, or (at your option) any
;; later version.
;; eris-cl is distributed in the hope that it will be useful, but WITHOUT ANY
;; WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
;; A PARTICULAR PURPOSE. See the GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License along with
;; eris-cl. If not, see <https://www.gnu.org/licenses/>.
;; This file contains the backend protocol.
(in-package :eris)
(defclass encoding-backend ()
((output-function :type function)))
(defclass decoding-backend ()
((fetch-function :type function)))
(defgeneric fetch-data (read-capability backend &key &allow-other-keys)
(:documentation
"Using the BACKEND, return a stream that decodes the provided READ-CAPABILITY
object."))
(defgeneric store-data (input backend &key secret &allow-other-keys)
(:documentation
"Using the BACKEND, store the INPUT, which is either a stream or an octet
vector. An additional 32-byte octet-vector SECRET can be provided in order to
protect the data from attacks against convergent encryption."))
;; Default methods
(defmethod fetch-data (read-capability (backend decoding-backend) &key &allow-other-keys)
(declare (type read-capability read-capability))
(with-slots (fetch-function) backend
(eris-decode read-capability fetch-function)))
(defmethod store-data (input (backend encoding-backend) &key (secret null-secret) &allow-other-keys)
(declare (type octet-vector secret))
(with-slots (output-function) backend
(eris-encode input ;; According to ERIS spec recommendation.
(if (> (etypecase input
(stream (file-length input))
(vector (length input)))
16384)
32kib
1kib)
output-function
:secret secret)))
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