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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 versqion.
;; 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/>.
(in-package :eris)
(defun pad (input block-size)
(declare (type (simple-array (unsigned-byte 8)) input)
(type integer block-size))
(let* ((pad-size (- block-size (mod (length input) block-size)))
(padded-input (adjust-array input (+ pad-size (length input)) :initial-element 0)))
(replace padded-input input)
(setf (aref padded-input (length input)) #x80)
padded-input))
(deftype block-size ()
`(member 1024 32768))
(defconstant 32kib 32768)
(defconstant 1kib 1024)
(eval-when
(:execute :load-toplevel :compile-toplevel)
(defclass reference-pair ()
((reference :initarg :reference :accessor reference :type (simple-array (unsigned-byte 8) 32))
(key :initarg :key :accessor key :type (simple-array (unsigned-byte 8) 32)))))
(define-constant null-secret (make-array 32 :element-type '(unsigned-byte 8) :initial-element 0) :test #'equalp)
(defun reference-pair-to-octets (pair buf &optional (start 0))
(replace buf (reference pair) :start1 start)
(replace buf (key pair) :start1 (+ 32 start)))
(defun octets-to-reference-pair (octets)
(let ((key (make-array 32 :element-type '(unsigned-byte 8)))
(reference (make-array 32 :element-type '(unsigned-byte 8))))
(replace reference octets)
(replace key octets :start2 32)
(make-instance 'reference-pair :key key :reference reference)))
(defun compute-reference (block)
(declare (type (simple-array (unsigned-byte 8)) block))
(let ((reference (make-array 32 :element-type '(unsigned-byte 8))))
(ironclad:digest-sequence :blake2/256 block :digest reference)
reference))
(declaim (inline make-nonce))
(defun make-nonce (level)
(let ((nonce (make-array 12 :element-type '(unsigned-byte 8) :initial-element 0)))
(setf (aref nonce 0) level)
nonce))
(defun encrypt-block (input secret reference)
(declare (type (simple-array (unsigned-byte 8)) input secret reference))
(let ((mac (ironclad:make-mac :blake2-mac secret :digest-length 32))
(key (make-array 32 :element-type '(unsigned-byte 8))))
(ironclad:update-mac mac input)
(ironclad:produce-mac mac :digest key)
;; NOT the IETF chacha. Need to fix this by patching ironclad. Maybe.
(ironclad:encrypt-in-place (ironclad:make-cipher :chacha :mode :stream :key key
:initialization-vector null-secret)
input)
(ironclad:digest-sequence :blake2/256 input :digest reference)
(make-instance 'reference-pair :key key :reference reference)))
(defun encrypt-internal-block (input reference nonce)
(declare (type (simple-array (unsigned-byte 8)) input secret reference))
(let ((key (make-array 32 :element-type '(unsigned-byte 8))))
(ironclad:digest-sequence :blake2/256 input :digest key)
;; NOT the IETF chacha. Need to fix this by patching ironclad. Maybe.
(ironclad:encrypt-in-place (ironclad:make-cipher :chacha :mode :stream :key key
:initialization-vector nonce)
input)
(ironclad:digest-sequence :blake2/256 input :digest reference)
(make-instance 'reference-pair :key key :reference reference)))
(defun decrypt-block (input key &optional (nonce null-secret))
(ironclad:decrypt-in-place
(ironclad:make-cipher :chacha :mode :stream :key key :initialization-vector nonce)
input)
input)
(defclass read-capability ()
((block-size :initarg :block-size
:accessor block-size
:type block-size
:documentation "A value of either 1024 or 1kb blocks.")
(level :initarg :level :accessor level :type (unsigned-byte 8))
(root-reference-pair :initarg :reference-pair :accessor reference-pair)))
(defun read-capability-to-octets (read-capability)
(declare (type read-capability read-capability))
(let ((cap (make-array 66 :element-type '(unsigned-byte 8))))
(case (block-size read-capability) ;; This depends on the version of the standard
(1024 (setf (aref cap 0) #x0a))
(32768 (setf (aref cap 0) #x0f)))
(setf (aref cap 1) (level read-capability))
(reference-pair-to-octets (reference-pair read-capability) cap 2)))
(defun octets-to-read-capability (octets)
(declare (type (simple-array (unsigned-byte 8) (66)) octets))
(let ((capability (make-instance 'read-capability)))
(setf (block-size capability)
(case (aref octets 0)
(#x0a 1kib)
(#x0f 32kib)
(t (error 'version-mismatch))))
(setf (level capability)
(aref octets 1))
(setf (reference-pair capability)
(octets-to-reference-pair (subseq-shared octets 2)))
capability))
(defun read-capability-to-urn (capability)
(concatenate 'string
"urn:eris:"
(bytes-to-base32-unpadded (read-capability-to-octets capability))))
(defun urn-to-read-capability (urn)
(octets-to-read-capability (base32-to-bytes-unpadded (subseq urn (1+ (position #\: urn :from-end t))))))
(defun reference-to-block-urn (reference)
(declare (type (simple-array (unsigned-byte 8) (32)) reference))
(concatenate 'string "urn:blake2b:" (bytes-to-base32-unpadded reference)))
(defun block-urn-to-reference (urn)
(declare (type string urn))
(base32-to-bytes-unpadded (subseq urn (1+ (position #\: urn :from-end t)))))
(defvar *output-hashmap* nil)
(defmacro output-block (ref-vector &rest expr)
`(let ((reference (compute-reference block)))
(if hash-output
(unless (gethash reference *output-hashmap*)
(let ((rk (encrypt-block block secret reference)))
(vector-push-extend rk ,ref-vector)
(funcall output-function block (reference rk))
(setf (gethash reference *output-hashmap*) t)))
(let ((rk (encrypt-block block secret reference)))
(vector-push-extend rk ,ref-vector)
(funcall output-function block (reference rk))))
,@expr))
(defmacro output-internal-block (ref-vector nonce &rest expr)
`(let ((reference (compute-reference block)))
(if hash-output
(unless (gethash reference *output-hashmap*)
(let ((rk (encrypt-internal-block block reference ,nonce)))
(vector-push-extend rk ,ref-vector)
(funcall output-function block (reference rk))
(setf (gethash reference *output-hashmap*) t)))
(let ((rk (encrypt-internal-block block reference ,nonce)))
(vector-push-extend rk ,ref-vector)
(funcall output-function block (reference rk))))
,@expr))
(defgeneric eris-encode (input block-size output-function &key secret hash-output)
(:documentation
"Encode an input into block-size (32kib or 1kib) blocks, that are output using
the function output-function. This function wil be called with two arguments: an
encoded block and a 32-byte reference octet vector.
An optional 32-byte secret can be passed for additional encryption using the
:secret keyword."))
(defmethod eris-encode ((input simple-array) block-size output-function &key (secret null-secret) hash-output)
(declare (type block-size block-size)
(type function output-function)
(type (simple-array (unsigned-byte 8) (32)) secret))
(setf input (pad input block-size))
(let ((reference-vector (make-array 16 :adjustable t :fill-pointer 0))
(*output-hashmap* (if hash-output (make-hash-table :test #'equalp) nil)))
(loop for block = (make-array block-size :element-type '(unsigned-byte 8) :initial-element 0)
for i = 0 then (incf i)
until (= (length input) (* i block-size))
do (progn
(replace block input :start2 (* i block-size))
(output-block reference-vector nil)))
(eris-create-tree reference-vector block-size output-function :hash-output hash-output)))
(defmethod eris-encode ((input stream) block-size output-function &key (secret null-secret) hash-output)
(declare (type block-size block-size)
(type function output-function)
(type (simple-array (unsigned-byte 8) (32)) secret))
(let ((reference-vector (make-array 16 :adjustable t :fill-pointer 0))
(*output-hashmap* (if hash-output (make-hash-table :test #'equalp) nil)))
(loop for block = (make-array block-size :element-type '(unsigned-byte 8) :initial-element 0)
for bytes-read = (read-sequence block input)
for i = 0 then (incf i)
if (< bytes-read block-size)
do (setf (aref block bytes-read) #x80)
do (output-block reference-vector nil)
until (< bytes-read block-size))
(eris-create-tree reference-vector block-size output-function :hash-output hash-output)))
(defun eris-create-tree (reference-vector block-size output-function &key hash-output)
(declare (type block-size block-size)
(type function output-function)
(type (simple-array (unsigned-byte 8) (32)) secret))
(loop with block-keys = (/ block-size 64)
with level = 0
with reference-vector-l = (make-array 16 :adjustable t :fill-pointer 0)
for nonce = (make-nonce (1+ level))
when (eql (length reference-vector) 1)
do (return (make-instance 'read-capability
:reference-pair (aref reference-vector 0)
:level level
:block-size block-size))
do (progn
(incf level)
;; loop across the key-reference vector and build the tree
(loop with block = (make-array block-size :element-type '(unsigned-byte 8) :initial-element 0)
for rk across reference-vector
with i = 0
when (eql i block-keys)
do (output-internal-block reference-vector-l nonce
(setf block (make-array block-size :element-type '(unsigned-byte 8) :initial-element 0)
i 0))
do (progn (reference-pair-to-octets rk block (* 64 i))
(incf i))
finally (unless (zerop i)
;; If i is zero, then the amount of blocks is just right. Otherwise add a final unfinished block.
(output-internal-block reference-vector-l nonce)))
(setf reference-vector reference-vector-l)
(setf reference-vector-l (make-array 16 :adjustable t :fill-pointer 0)))))
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