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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/>.
(in-package :eris)
(deftype block-size ()
`(member 1024 32768))
(defconstant 32kib 32768)
(defconstant 1kib 1024)
(define-constant null-secret (make-array 32 :element-type 'octet :initial-element 0)
:test #'equalp
:documentation
"32-byte null vector.")
(defun make-nonce (level)
(let ((nonce (make-array 12 :element-type 'octet :initial-element 0)))
(setf (aref nonce 0) level)
nonce))
(defun encrypt-block (input secret)
(declare (type octet-vector input secret))
(let ((mac (ironclad:make-mac :blake2-mac secret :digest-length 32))
(rk (make-array 64 :element-type 'octet))) ;; reference-key pair
(ironclad:update-mac mac input)
(ironclad:produce-mac mac :digest rk :digest-start 32) ;; get key
(ironclad:encrypt-in-place (ironclad:make-cipher :chacha :mode :stream :key (subseq rk 32 64)
:initialization-vector null-secret)
input) ;; encrypt block
(ironclad:digest-sequence :blake2/256 input :digest rk) ;; get reference
rk))
(defun encrypt-internal-block (input nonce)
(declare (type octet-vector input))
(let ((rk (make-array 64 :element-type 'octet))) ;; reference-key pair
(ironclad:digest-sequence :blake2/256 input :digest rk :digest-start 32);; get key
(ironclad:encrypt-in-place (ironclad:make-cipher :chacha :mode :stream :key (subseq rk 32 64)
:initialization-vector nonce)
input) ;; encrypt block
(ironclad:digest-sequence :blake2/256 input :digest rk) ;; get reference
rk))
(defun decrypt-block (input rk &optional (nonce null-secret))
(declare (type octet-vector input rk nonce))
(ironclad:decrypt-in-place
(ironclad:make-cipher :chacha :mode :stream :key (subseq rk 32 64) :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 octet)
(root-reference-pair :initarg :reference-pair :accessor reference-pair))
(:documentation "Class representing the concept of an ERIS read capability."))
(-> read-capability-to-octets (read-capability) (octet-vector 66))
(defun read-capability-to-octets (read-capability)
"Convert a read-capability object to its standard binary representation. Returns
a (simple-array (unsigned-byte 8)) object."
(declare (type read-capability read-capability))
(let ((cap (make-array 66 :element-type 'octet)))
(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))
(replace cap (reference-pair read-capability) :start1 2)
cap))
(-> octets-to-read-capability ((octet-vector 66)) (values read-capability &optional))
(defun octets-to-read-capability (octets)
"Convert the standard binary representation for ERIS read capabilities into a
read-capability object. Returns the read-capability.
An ERIS:VERSION-MISMATCH condition may be signaled if the corresponding
versioning bytes are not supported by eris-cl."
(declare (type (octet-vector 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)
(let ((kr (make-array 64 :element-type 'octet)))
(replace kr octets :start2 2)
kr)) ;; TODO CHECK CORRECTNESS
capability))
(-> read-capability-to-urn (read-capability) string)
(defun read-capability-to-urn (capability)
"Convert a read-capability object into a URN string."
(declare (type read-capability capability))
(concatenate 'string
"urn:eris:"
(bytes-to-base32-unpadded (read-capability-to-octets capability))))
(-> urn-to-read-capability (string) (values read-capability &optional))
(defun urn-to-read-capability (urn)
"Convert a urn:eris URN string into a read-capability object."
(declare (type string urn))
(octets-to-read-capability (base32-to-bytes-unpadded (subseq urn (1+ (position #\: urn :from-end t))))))
(-> reference-to-block-urn ((octet-vector 32)) string)
(defun reference-to-block-urn (reference)
"Convert a 32-byte block reference into a URN string."
(declare (type (octet-vector 32) reference))
(concatenate 'string "urn:blake2b:" (bytes-to-base32-unpadded reference)))
(-> block-urn-to-reference (string) (values (octet-vector 32) &optional))
(defun block-urn-to-reference (urn)
"Convert a urn:blake2b URN string into a 32-byte block reference vector."
(declare (type string urn))
(base32-to-bytes-unpadded (subseq urn (1+ (position #\: urn :from-end t)))))
(defun pad (input block-size)
(declare (type octet-vector 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))
(defmacro output-block (ref-vector)
`(let ((rk (encrypt-block block secret)))
(vector-push-extend rk ,ref-vector)
(funcall output-function block (subseq rk 0 32))))
(defmacro output-internal-block (ref-vector nonce)
`(let ((rk (encrypt-internal-block block ,nonce)))
(vector-push-extend rk ,ref-vector)
(funcall output-function block (subseq rk 0 32))))
(defgeneric eris-encode (input block-size output-function &key secret)
(: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, and it MUST return
a (SIMPLE-ARRAY (UNSIGNED-BYTE 8)) of equal size to the one given, which will be
destructively modified. Returns a read-capability object.
An optional 32-byte secret can be passed for additional encryption using the
SECRET keyword argument."))
(defmethod eris-encode ((input vector) block-size output-function &key (secret null-secret))
(declare (type block-size block-size)
(type function output-function)
(type (octet-vector 32) secret))
(setf input (pad input block-size))
(let ((reference-vector (make-array 16 :adjustable t :fill-pointer 0))
(block (make-array block-size :element-type 'octet :initial-element 0)))
(declare (type octet-vector block))
(loop for i = 0 then (incf i)
until (= (length input) (* i block-size))
do (progn (replace block input :start2 (* i block-size))
(setf block (output-block reference-vector))
(fill block 0)))
;; always bzero the buffer; this is unoptimal (it only needs to be zeroed out to eliminate trailing junk)
;; TODO: consider removing this entire function and replacing it with an octet stream
(eris-create-tree reference-vector block-size output-function)))
(defmethod eris-encode ((input stream) block-size output-function &key (secret null-secret))
"This method does not handle any IO related conditions."
(declare (type block-size block-size)
(type function output-function)
(type (octet-vector 32) secret))
(let ((reference-vector (make-array 16 :adjustable t :fill-pointer 0))
(block (make-array block-size :element-type 'octet :initial-element 0)))
(declare (type octet-vector block))
(loop for bytes-read = (read-sequence block input)
for i = 0 then (incf i)
if (< bytes-read block-size)
do (progn (setf (aref block bytes-read) #x80)
(fill block 0 :start (1+ bytes-read))) ;; bzero the buffer here to eliminate trailing junk
do (progn (setf block (output-block reference-vector)))
until (< bytes-read block-size))
(eris-create-tree reference-vector block-size output-function)))
(defun eris-create-tree (reference-vector block-size output-function)
(declare (type block-size block-size)
(type function output-function))
(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 'octet :initial-element 0)
for rk across reference-vector
with i = 0
when (eql i block-keys)
do (progn (setf block (output-internal-block reference-vector-l nonce))
(setf i 0)
(fill block 0))
do (progn (replace block rk :start1 (* 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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