;;;; Copyright (C) 2020 Julien Lepiller <julien@lepiller.eu>

;;;; 

;;;; This library 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.

;;;; 

;;;; This library 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

;;;; Lesser General Public License for more details.

;;;; 

;;;; You should have received a copy of the GNU Lesser General Public

;;;; License along with this library; if not, write to the Free Software

;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

;;;; 

(define-module (http-signature ontology)

  #:use-module (activitystreams activitystreams)

  #:use-module (ice-9 match)

  #:use-module (jsonld json)

  #:use-module (web uri)

  #:export (security-ontology))

(define sec:vocab "https://w3id.org/security#")

(define* (make-sec-type label #:key (uri (string-append sec:vocab label))

                        (comment "") (subclass-of '()))

  (make-as-type label #:uri uri #:comment comment #:subclass-of subclass-of))

(define* (make-sec-property label domain range

                           #:key (uri (string-append sec:vocab label))

                           (functional? #f) (subproperty-of '()) (comment ""))

  (make-as-property label domain range #:uri uri #:functional? functional?

                    #:subproperty-of subproperty-of #:comment comment))

(define date? (@@ (activitystreams ontology) date?))

(define iri? (@@ (activitystreams ontology) iri?))

;; Classes

(define sec:Digest

  (make-sec-type

    "Digest"

    #:comment

    "This class represents a message digest that may be used for data integrity

verification.  The digest algorithm used will determine the cryptographic

properties of the digest."))

(define sec:EncryptedMessage

  (make-sec-type

    "EncryptedMessage"

    #:comment

    "A class of messages that are obfuscated in some cryptographic manner.

These messages are incredibly difficult to decrypt without the proper

decryption key."))

(define sec:Signature

  (make-sec-type

    "Signature"

    #:comment

    "This class represents a digital signature on serialized data.  It is an

abstract class and should not be used other than for Semantic Web reasoning

purposes, such as by a reasoning agent."))

(define sec:GraphSignature2012

  (make-sec-type

    "GraphSignature2012"

    #:subclass-of (list sec:Signature)

    #:comment

    "A graph signature is used for digital signatures on RDF graphs.  The

default canonicalization mechanism is specified in the RDF Graph normalization

specification, which effectively deterministically names all unnamed nodes.

The default signature mechanism uses a SHA-256 digest and RSA to perform the

digital signature."))

(define sec:LinkedDataSignature2015

  (make-sec-type

    "LinkedDataSignature2015"

    #:subclass-of (list sec:Signature)

    #:comment

    "A Linked Data signature is used for digital signatures on RDF Datasets.

The default canonicalization mechanism is specified in the RDF Dataset

Normalization specification, which effectively deterministically names all

unnamed nodes.  The default signature mechanism uses a SHA-256 digest and RSA

to perform the digital signature.  This signature uses a algorithm for

producing the data that it signs and verifies that is different from other

Linked Data signatures."))

(define sec:LinkedDataSignature2016

  (make-sec-type

    "LinkedDataSignature2016"

    #:subclass-of (list sec:Signature)

    #:comment

    "A Linked Data signature is used for digital signatures on RDF Datasets.

The default canonicalization mechanism is specified in the RDF Dataset

Normalization specification, which effectively deterministically names all

unnamed nodes. The default signature mechanism uses a SHA-256 digest and RSA

to perform the digital signature."))

(define sec:Key

  (make-sec-type

    "Key"

    #:comment

    "This class represents a cryptographic key that may be used for encryption,

decryption, or digitally signing data."))

(define sec-types (list sec:Digest sec:EncryptedMessage sec:Signature

                        sec:GraphSignature2012 sec:LinkedDataSignature2015

                        sec:LinkedDataSignature2016 sec:Key))

(define sec:authenticationTag

  (make-sec-property

    "authenticationTag" "EncryptedMessage" string?

    #:comment

    "Not specified"))

(define sec:creator

  (make-sec-property

    "creator" "Signature" iri?

    #:comment

    "Not specified"))

(define sec:cipherAlgorithm

  (make-sec-property

    "cipherAlgorithm" "EncryptedMessage" string?

    #:comment

    "The cipher algorithm describes the mechanism used to encrypt a message.

It is typically a string expressing the cipher suite, the strength of the

cipher, and a block cipher mode."))

(define sec:cipherData

  (make-sec-property

    "cipherData" "EncryptedMessage" string?

    #:comment

    "Cipher data an opaque blob of information that is used to specify an

encrypted message."))

(define sec:digestAlgorithm

  (make-sec-property

    "digestAlgorithm" "Digest" string?

    #:comment

    "The digest algorithm is used to specify the cryptographic function to use

when generating the data to be digitally signed.  Typically, data that is to be

signed goes through three steps: 1) canonicalization, 2) digest, and

3) signature.  This property is used to specify the algorithm that should be

used for step #2.  A signature class typically specifies a default digest

method, so this property is typically used to specify information for a

signature algorithm."))

(define sec:digestValue

  (make-sec-property

    "digestValue" "Digest" string?

    #:comment

    "The digest value is used to express the output of the digest algorithm

expressed in Base-16 (hexadecimal) format."))

(define sec:cipherKey

  (make-sec-property

    "cipherKey" "EncryptedMessage" string?

    #:comment

    "A cipher key is a symmetric key that is used to encrypt or decrypt a

piece of information.  The key itself may be expressed in clear text or

encrypted."))

(define sec:expires

  (make-sec-property

    "expires" "" string?

    #:comment

    "The expiration time is typically associated with a Key and specifies when

the validity of the key will expire.  It is considered a best practice to only

create keys that have very definite expiration periods.  This period is

typically set to between six months and two years.  An digital signature

created using an expired key MUST be marked as invalid by any software

attempting to verify the signature."))

(define sec:initializationVector

  (make-sec-property

    "initializationVector" "EncryptedMessage" string?

    #:comment

    "The initialization vector (IV) is a byte stream that is typically used to

initialize certain block cipher encryption schemes.  For a receiving

application to be able to decrypt a message, it must know the decryption key

and the initialization vector.  The value is typically base-64 encoded."))

(define sec:nonce

  (make-sec-property

    "nonce" "" string?

    #:comment

    "This property is used in conjunction with the input to the signature

hashing function in order to protect against replay attacks.  Typically,

receivers need to track all nonce values used within a certain time period

in order to ensure that an attacker cannot merely re-send a compromised

packet in order to execute a privileged request."))

(define sec:canonicalizationAlgorithm

  (make-sec-property

    "canonicalizationAlgorithm" "" (list iri? string?)

    #:comment

    "The canonicalization algorithm is used to transform the input data into a

form that can be passed to a cryptographic digest method.  The digest is then

digitally signed using a digital signature algorithm.  Canonicalization ensures

that a piece of software that is generating a digital signature is able to do

so on the same set of information in a deterministic manner."))

(define sec:owner

  (make-sec-property

    "owner" "Key" iri?

    #:comment

    "An owner is an entity that claims control over a particular resource.

Note that ownership is best validated as a two-way relationship where the

owner claims ownership over a particular resource, and the resource clearly

identifies its owner."))

(define sec:password

  (make-sec-property

    "password" "" string?

    #:comment

    "A secret that is used to generate a key that can be used to encrypt or

decrypt message.  It is typically a string value."))

(define sec:privateKeyPem

  (make-sec-property

    "privateKeyPem" "Key" string?

    #:comment

    "A private key PEM property is used to specify the PEM-encoded version of

the private key.  This encoding is compatible with almost every Secure Sockets

Layer library implementation and typically plugs directly into functions

intializing private keys."))

(define sec:publicKey

  (make-sec-property

    "publicKey" "EncryptedMessage" iri?

    #:comment

    "A public key property is used to specify a URL that contains information

about a public key."))

(define sec:publicKeyPem

  (make-sec-property

    "publicKeyPem" "Key" string?

    #:comment

    "A public key PEM property is used to specify the PEM-encoded version of

the public key.  This encoding is compatible with almost every Secure Sockets

Layer library implementation and typically plugs directly into functions

intializing public keys."))

(define sec:publicKeyService

  (make-sec-property

    "publicKeyService" "" string?

    #:comment

    "The publicKeyService property is used to express the REST URL that provides

public key management services as defined by the Web Key specification."))

(define sec:revoked

  (make-sec-property

    "revoked" "" date?

    #:comment

    "The revocation time is typically associated with a Key that has been

marked as invalid as of the date and time associated with the property.  Key

revocations are often used when a key is compromised, such as the theft of the

private key, or during the course of best-practice key rotation schedules."))

(define sec:signature

  (make-sec-property

    ;; XXX: not correct, there is no defined domain

    "signature" "Object" "Signature"

    #:comment

    "The signature property is used to associate a signature with a graph of

information.  The signature property is typically not included in the

canonicalized graph that is then digested, and digitally signed."))

(define sec:signatureValue

  (make-sec-property

    "signatureValue" "Signature" string?

    #:comment

    "The signature value is used to express the output of the signature

algorithm expressed in base-64 format."))

(define sec:signatureAlgorithm

  (make-sec-property

    "signatureAlgorithm" "Signature" string?

    #:comment

    "The signature algorithm is used to specify the cryptographic signature

function to use when digitally signing the digest data.  Typically, text to be

signed goes through three steps: 1) canonicalization, 2) digest, and

3) signature.  This property is used to specify the algorithm that should be

used for step #3.  A signature class typically specifies a default signature

algorithm, so this property rarely needs to be used in practice when

specifying digital signatures."))

(define sec-properties

  (list sec:cipherAlgorithm sec:cipherData sec:digestAlgorithm sec:digestValue

        sec:cipherKey sec:expires sec:initializationVector sec:nonce

        sec:canonicalizationAlgorithm sec:owner sec:password

        sec:privateKeyPem sec:publicKey sec:publicKeyPem sec:publicKeyService

        sec:revoked sec:signature sec:signatureValue sec:signatureAlgorithm))

(define security-ontology (append sec-types sec-properties))