< draft-ietf-lpwan-coap-static-context-hc-06.txt		draft-ietf-lpwan-coap-static-context-hc-07.txt >
	lpwan Working Group A. Minaburo		lpwan Working Group A. Minaburo
	Internet-Draft Acklio		Internet-Draft Acklio
	Intended status: Informational L. Toutain		Intended status: Standards Track L. Toutain
	Expires: August 9, 2019 Institut MINES TELECOM; IMT Atlantique		Expires: November 25, 2019 Institut MINES TELECOM; IMT Atlantique
	R. Andreasen		R. Andreasen
	Universidad de Buenos Aires		Universidad de Buenos Aires
	February 05, 2019		May 24, 2019
	LPWAN Static Context Header Compression (SCHC) for CoAP		LPWAN Static Context Header Compression (SCHC) for CoAP
	draft-ietf-lpwan-coap-static-context-hc-06		draft-ietf-lpwan-coap-static-context-hc-07
	Abstract		Abstract
	This draft defines the way SCHC header compression can be applied to		This draft defines the way SCHC header compression can be applied to
	CoAP headers. The CoAP header structure differs from IPv6 and UDP		CoAP headers. The CoAP header structure differs from IPv6 and UDP
	protocols since CoAP		protocols since CoAP
	use a flexible header with a variable number of options themselves of		uses a flexible header with a variable number of options themselves
	a variable length. The CoAP protocol is asymmetric in its format		of variable length. The CoAP protocol is asymmetric in its message
	messages, the format of the header packet in the request messages is		format, the format of the header packet in the request messages is
	different than in the response messages. Most of the compression		different from that in the response messages. Most of the
	mechanisms have been introduced in		compression mechanisms have been introduced in
	[I-D.ietf-lpwan-ipv6-static-context-hc], this document explains how		[I-D.ietf-lpwan-ipv6-static-context-hc], this document explains how
	to use the SCHC compression for CoAP.		to use the SCHC compression for CoAP.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on August 9, 2019.		This Internet-Draft will expire on November 25, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 29 ¶		skipping to change at page 2, line 29 ¶
	3. CoAP Compression with SCHC . . . . . . . . . . . . . . . . . 4		3. CoAP Compression with SCHC . . . . . . . . . . . . . . . . . 4
	4. Compression of CoAP header fields . . . . . . . . . . . . . . 6		4. Compression of CoAP header fields . . . . . . . . . . . . . . 6
	4.1. CoAP version field . . . . . . . . . . . . . . . . . . . 6		4.1. CoAP version field . . . . . . . . . . . . . . . . . . . 6
	4.2. CoAP type field . . . . . . . . . . . . . . . . . . . . . 6		4.2. CoAP type field . . . . . . . . . . . . . . . . . . . . . 6
	4.3. CoAP code field . . . . . . . . . . . . . . . . . . . . . 6		4.3. CoAP code field . . . . . . . . . . . . . . . . . . . . . 6
	4.4. CoAP Message ID field . . . . . . . . . . . . . . . . . . 6		4.4. CoAP Message ID field . . . . . . . . . . . . . . . . . . 6
	4.5. CoAP Token fields . . . . . . . . . . . . . . . . . . . . 7		4.5. CoAP Token fields . . . . . . . . . . . . . . . . . . . . 7
	5. CoAP options . . . . . . . . . . . . . . . . . . . . . . . . 7		5. CoAP options . . . . . . . . . . . . . . . . . . . . . . . . 7
	5.1. CoAP Content and Accept options. . . . . . . . . . . . . 7		5.1. CoAP Content and Accept options. . . . . . . . . . . . . 7
	5.2. CoAP option Max-Age field, CoAP option Uri-Host and Uri-		5.2. CoAP option Max-Age field, CoAP option Uri-Host and Uri-
	Port fields . . . . . . . . . . . . . . . . . . . . . . . 7		Port fields . . . . . . . . . . . . . . . . . . . . . . . 8
	5.3. CoAP option Uri-Path and Uri-Query fields . . . . . . . . 8		5.3. CoAP option Uri-Path and Uri-Query fields . . . . . . . . 8
	5.3.1. Variable length Uri-Path and Uri-Query . . . . . . . 8		5.3.1. Variable length Uri-Path and Uri-Query . . . . . . . 8
	5.3.2. Variable number of path or query elements . . . . . . 9		5.3.2. Variable number of path or query elements . . . . . . 9
	5.4. CoAP option Size1, Size2, Proxy-URI and Proxy-Scheme		5.4. CoAP option Size1, Size2, Proxy-URI and Proxy-Scheme
	fields . . . . . . . . . . . . . . . . . . . . . . . . . 9		fields . . . . . . . . . . . . . . . . . . . . . . . . . 9
	5.5. CoAP option ETag, If-Match, If-None-Match, Location-Path		5.5. CoAP option ETag, If-Match, If-None-Match, Location-Path
	and Location-Query fields . . . . . . . . . . . . . . . . 9		and Location-Query fields . . . . . . . . . . . . . . . . 9
	6. Other RFCs . . . . . . . . . . . . . . . . . . . . . . . . . 9		6. Other RFCs . . . . . . . . . . . . . . . . . . . . . . . . . 10
	6.1. Block . . . . . . . . . . . . . . . . . . . . . . . . . . 9		6.1. Block . . . . . . . . . . . . . . . . . . . . . . . . . . 10
	6.2. Observe . . . . . . . . . . . . . . . . . . . . . . . . . 10		6.2. Observe . . . . . . . . . . . . . . . . . . . . . . . . . 10
	6.3. No-Response . . . . . . . . . . . . . . . . . . . . . . . 10		6.3. No-Response . . . . . . . . . . . . . . . . . . . . . . . 10
	6.4. Time Scale . . . . . . . . . . . . . . . . . . . . . . . 10		6.4. Time Scale . . . . . . . . . . . . . . . . . . . . . . . 10
	6.5. OSCORE . . . . . . . . . . . . . . . . . . . . . . . . . 10		6.5. OSCORE . . . . . . . . . . . . . . . . . . . . . . . . . 11
	7. Examples of CoAP header compression . . . . . . . . . . . . . 12		7. Examples of CoAP header compression . . . . . . . . . . . . . 12
	7.1. Mandatory header with CON message . . . . . . . . . . . . 12		7.1. Mandatory header with CON message . . . . . . . . . . . . 12
	7.2. OSCORE Compression . . . . . . . . . . . . . . . . . . . 13		7.2. OSCORE Compression . . . . . . . . . . . . . . . . . . . 13
	7.3. Example OSCORE Compression . . . . . . . . . . . . . . . 17		7.3. Example OSCORE Compression . . . . . . . . . . . . . . . 17
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
	9. Security considerations . . . . . . . . . . . . . . . . . . . 27		9. Security considerations . . . . . . . . . . . . . . . . . . . 28
	10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 27		10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28
	11. Normative References . . . . . . . . . . . . . . . . . . . . 27		11. Normative References . . . . . . . . . . . . . . . . . . . . 29
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
	1. Introduction		1. Introduction
	CoAP [rfc7252] is an implementation of the REST architecture for		CoAP [rfc7252] is an implementation of the REST architecture for
	constrained devices. Nevertheless, if limited, the size of a CoAP		constrained devices. Although CoAP was designed for constrained
	header may be too large for LPWAN constraints and some compression		devices, the size of a CoAP header may still be too large for LPWAN
	may be needed to reduce the header size.		constraints and some compression may be needed to reduce the header
			size.
	[I-D.ietf-lpwan-ipv6-static-context-hc] defines a header compression		[I-D.ietf-lpwan-ipv6-static-context-hc] defines a header compression
	mechanism for LPWAN network based on a static context. The context		mechanism for LPWAN network based on a static context. The context
	is said static since the field description composing the Rules and		is said static since the field description composing the Rules are
	the context are not learned during the packet exchanges but are		not learned during the packet exchanges but are previously defined.
	previously defined. The context(s) is(are) known by both ends before		The context(s) is(are) known by both ends before transmission.
	transmission.
	A context is composed of a set of rules that are referenced by Rule		A context is composed of a set of rules that are referenced by Rule
	IDs (identifiers). A rule contains an ordered list of the fields		IDs (identifiers). A rule contains an ordered list of the fields
	descriptions containing a field ID (FID), its length (FL) and its		descriptions containing a field ID (FID), its length (FL) and its
	position (FP), a direction indicator (DI) (upstream, downstream and		position (FP), a direction indicator (DI) (upstream, downstream and
	bidirectional) and some associated Target Values (TV). Target Value		bidirectional) and some associated Target Values (TV). Target Value
	indicates the value that can be expected. TV can also be a list of		indicates the value that can be expected. TV can also be a list of
	values. A Matching Operator (MO) is associated to each header field		values. A Matching Operator (MO) is associated to each header field
	description. The rule is selected if all the MOs fit the TVs for all		description. The rule is selected if all the MOs fit the TVs for all
	fields. In that case, a Compression/Decompression Action (CDA)		fields. In that case, a Compression/Decompression Action (CDA)
	associated to each field defines the link between the compressed and		associated to each field defines the link between the compressed and
	decompressed value for each of the header fields. Compression		decompressed value for each of the header fields. Compression
	results mainly in 4 actions: send the field value, send nothing, send		results mainly in 4 actions: send the field value, send nothing, send
	less significant bits of a field, send an index. Values sent are		less significant bits of a field, send an index. Values sent are
	called Compression Residues and follows the rule ID.		called Compression Residues and follows the rule ID.
	2. SCHC Compression Process		2. SCHC Compression Process
	The SCHC Compression rules can be applied to CoAP flows. SCHC		The SCHC Compression rules can be applied to CoAP flows. SCHC
	Compression of the CoAP header may be done in conjunction with the		Compression of the CoAP header MAY be done in conjunction with the
	above layers (IPv6/UDP) or independently. The SCHC adaptation layers		above layers (IPv6/UDP) or independently. The SCHC adaptation layers
	as described in [I-D.ietf-lpwan-ipv6-static-context-hc] may be used		as described in [I-D.ietf-lpwan-ipv6-static-context-hc] may be used
	as as shown in the Figure 1.		as shown in Figure 1.
	^ +------------+ ^ +------------+ ^ +------------+		^ +------------+ ^ +------------+ ^ +------------+
	| | CoAP | | | CoAP | inner | | CoAP |		| | CoAP | | | CoAP | inner | | CoAP |
	| +------------+ v +------------+ x | OSCORE |		| +------------+ v +------------+ x | OSCORE |
	| | UDP | | DTLS | outer | +------------+		| | UDP | | DTLS | outer | +------------+
	| +------------+ +------------+ | | UDP |		| +------------+ +------------+ | | UDP |
	| | IPv6 | | UDP | | +------------+		| | IPv6 | | UDP | | +------------+
	v +------------+ +------------+ | | IPv6 |		v +------------+ +------------+ | | IPv6 |
	| IPv6 | v +------------+		| IPv6 | v +------------+
	+------------+		+------------+
	Figure 1: rule scope for CoAP		Figure 1: rule scope for CoAP
	Figure 1 shows some examples for CoAP architecture and the SCHC		Figure 1 shows some examples for CoAP architecture and the SCHC
	rule's scope. A rule can covers all headers from IPv6 to CoAP, SCHC		rule's scope. A rule can cover all headers from IPv6 to CoAP, in
	C/D is done in the device and at the LPWAN boundary. If an end-to-		which case SCHC C/D is performed at the device and at the LPWAN
	end encryption mechanisms is used between the device and the		boundary. If an end-to-end encryption mechanisms is used between the
	application. CoAP must be compressed independently of the other		device and the application, CoAP MAY be compressed independently of
	layers. The rule ID and the compression residue are encrypted using		the other layers. The rule ID and the compression residue are
	a mechanism such as DTLS. Only the other end can decipher the		encrypted using a mechanism such as DTLS. Only the other end can
	information.		decipher the information.
	Layers below may also be compressed using other SCHC rules (this is		Layers below may also be compressed using other SCHC rules (this is
	out of the scope of this document). OSCORE		out of the scope of this document). OSCORE
	[I-D.ietf-core-object-security] can also define 2 rules to compress		[I-D.ietf-core-object-security] can also define 2 rules to compress
	the CoAP message. A first rule focuses on the inner header and is		the CoAP message. A first rule focuses on the inner header and is
	end to end, a second rule may compress the outer header and the layer		end to end, a second rule may compress the outer header and the
	above. SCHC C/D for inner header is done by both ends, SCHC C/D for		layers below. SCHC C/D for inner header is done by both ends, SCHC
	outer header and other headers is done between the device and the		C/D for outer header and other headers is done between the device and
	LPWAN boundary.		the LPWAN boundary.
	3. CoAP Compression with SCHC		3. CoAP Compression with SCHC
	CoAP differs from IPv6 and UDP protocols on the following aspects:		CoAP differs from IPv6 and UDP protocols on the following aspects:
	o IPv6 and UDP are symmetrical protocols. The same fields are found		o IPv6 and UDP are symmetrical protocols. The same fields are found
	in the request and in the response, only the location in the		in the request and in the response, only the location in the
	header may vary (e.g. source and destination fields). A CoAP		header may vary (e.g. source and destination fields). A CoAP
	request is different from a response. For example, the URI-path		request is different from a response. For example, the URI-path
	option is mandatory in the request and is not found in the		option is mandatory in the request and is not found in the
	response, a request may contain an Accept option and the response		response, a request may contain an Accept option and the response
	a Content option.		a Content option.
	[I-D.ietf-lpwan-ipv6-static-context-hc] defines the use of a		[I-D.ietf-lpwan-ipv6-static-context-hc] defines the use of a
	message direction (DI) when processing the rule which allows the		message direction (DI) in the Field Description, which allows a
	description of message header format in both directions.		single Rule to process message headers differently in both
			directions.
	o Even when a field is "symmetric" (i.e. found in both directions)		o Even when a field is "symmetric" (i.e. found in both directions)
	the values carried in each direction are different. Combined with		the values carried in each direction are different. Combined with
	a matching list in the TV, this will allow to reduce the range of		a matching list in the TV, this allows reducing the range of
	expected values in a particular direction and therefore reduce the		expected values in a particular direction and therefore reduce the
	size of a compression residue. For instance, if a client sends		size of the compression residue. For instance, if a client sends
	only CON request, the type can be elided by compression and the		only CON request, the type can be elided by compression and the
	answer may use one bit to carry either the ACK or RST type. Same		answer may use one single bit to carry either the ACK or RST type.
	behavior can be applied to the CoAP Code field (0.0X code are		The same behavior can be applied to the CoAP Code field (0.0X code
	present in the request and Y.ZZ in the answer). The direction		are present in the request and Y.ZZ in the answer). The direction
	allows to split in two parts the possible values for each		allows splitting in two parts the possible values for each
	direction.		direction.
	o In IPv6 and UDP header fields have a fixed size. In CoAP, Token		o In IPv6 and UDP, header fields have a fixed size. In CoAP, Token
	size may vary from 0 to 8 bytes, length is given by a field in the		size may vary from 0 to 8 bytes, the length being given by a field
	header. More systematically, the CoAP options are described using		in the header. More systematically, the CoAP options are
	the Type-Length-Value.		described using the Type-Length-Value.
	[I-D.ietf-lpwan-ipv6-static-context-hc] offers the possibility to		[I-D.ietf-lpwan-ipv6-static-context-hc] offers the possibility to
	define a function for the Field Length in the Field Description.		define a function for the Field Length in the Field Description.
	o In CoAP headers, a field can be duplicated several times, for		o In CoAP headers, a field can be present several times. This is
	instances, elements of an URI (path or queries). The position		typical for elements of an URI (path or queries). The position
	defined in a rule, associated to a Field ID, can be used to		defined in a rule, associated to a Field ID, can be used to
	identify the proper element.		identify the proper instance.
	[I-D.ietf-lpwan-ipv6-static-context-hc] allows a Field id to		[I-D.ietf-lpwan-ipv6-static-context-hc] allows a Field ID to
	appears several times in the rule, the Field Position (FP) removes		appears several times in the rule, the Field Position (FP) removes
	ambiguities for the matching operation.		ambiguities for the matching operation.
	o Field size defined in the CoAP protocol can be too large regarding		o Field sizes defined in the CoAP protocol can be too large
	LPWAN traffic constraints. This is particularly true for the		regarding LPWAN traffic constraints. This is particularly true
	message ID field or Token field. The use of MSB MO can be used to		for the message ID field or Token field. The MSB MO can be used
	reduce the information carried on LPWANs.		to reduce the information carried on LPWANs.
	o CoAP also obeys to the client/server paradigm and the compression		o CoAP also obeys the client/server paradigm and the compression
	rate can be different if the request is issued from an LPWAN node		ratio can be different if the request is issued from an LPWAN
	or from an non LPWAN device. For instance a Device (Dev) aware of		device or from an non LPWAN device. For instance a Device (Dev)
	LPWAN constraints can generate a 1 byte token, but a regular CoAP		aware of LPWAN constraints can generate a 1 byte token, but a
	client will certainly send a larger token to the Thing. SCHC		regular CoAP client will certainly send a larger token to the Dev.
	compression will not modify the values to offer a better		SCHC compression will not modify the values to offer a better
	compression rate. Nevertheless a proxy placed before the		compression rate. Nevertheless, a proxy placed before the
	compressor may change some field values to offer a better		compressor may change some field values to offer a better
	compression rate and maintain the necessary context for		compression ratio and maintain the necessary context for
	interoperability with existing CoAP implementations.		interoperability with existing CoAP implementations.
	4. Compression of CoAP header fields		4. Compression of CoAP header fields
	This section discusses of the compression of the different CoAP		This section discusses the compression of the different CoAP header
	header fields.		fields.
	4.1. CoAP version field		4.1. CoAP version field
	This field is bidirectional and must be elided during the SCHC		This field is bidirectional and MUST be elided during the SCHC
	compression, since it always contains the same value. In the future,		compression, since it always contains the same value. In the future,
	if new version of CoAP are defined, new rules ID will be defined		if new versions of CoAP are defined, new rules will be defined to
	avoiding ambiguities between versions.		avoid ambiguities between versions.
	4.2. CoAP type field		4.2. CoAP type field
	[rfc7252] defines 4 types of messages: CON, NON, ACK and RST. The		[rfc7252] defines 4 types of messages: CON, NON, ACK and RST. The
	latter two ones are a response of the two first ones. If the device		last two are a response to the first two. If the device plays a
	plays a specific role, a rule can exploit these property with the		specific role, a rule can exploit these properties with the mapping
	mapping list: [CON, NON] for one direction and [ACK, RST] for the		list: [CON, NON] for one direction and [ACK, RST] for the other
	other direction. Compression residue is reduced to 1 bit.		direction. Compression residue is reduced to 1 bit.
	The field must be elided if for instance a client is sending only NON		The field SHOULD be elided if for instance a client is sending only
	or CON messages.		NON or CON messages.
	In any case, a rule must be defined to carry RST to a client.		In any case, a rule MUST be defined to carry RST to a client.
	4.3. CoAP code field		4.3. CoAP code field
	The compression of the CoAP code field follows the same principle as		The compression of the CoAP code field follows the same principle as
	for the CoAP type field. If the device plays a specific role, the		for the CoAP type field. If the device plays a specific role, the
	set of code values can be split in two parts, the request codes with		set of code values can be split in two parts, the request codes with
	the 0 class and the response values.		the 0 class and the response values.
	If the device implement only a CoAP client, the request code can be		If the device only implements a CoAP client, the request code can be
	reduced to the set of request the client is able to process.		reduced to the set of requests the client is able to process.
	All the response codes should be compressed with a SCHC rule.		All the response codes MUST be compressed with a SCHC rule.
	4.4. CoAP Message ID field		4.4. CoAP Message ID field
	This field is bidirectional and is used to manage acknowledgments.		This field is bidirectional and is used to manage acknowledgments.
	Server memorizes the value for a EXCHANGE_LIFETIME period (by default		The server memorizes the value for a EXCHANGE_LIFETIME period (by
	247 seconds) for CON messages and a NON_LIFETIME period (by default		default 247 seconds) for CON messages and a NON_LIFETIME period (by
	145 seconds) for NON messages. During that period, a server		default 145 seconds) for NON messages. During that period, a server
	receiving the same Message ID value will process the message as a		receiving the same Message ID value will process the message as a
	retransmission. After this period, it will be processed as a new		retransmission. After this period, it will be processed as a new
	messages.		message.
	In case the Device is a client, the size of the message ID field may		In case the Device is a client, the size of the message ID field may
	the too large regarding the number of messages sent. Client may use		be too large regarding the number of messages sent. The client
	only small message ID values, for instance 4 bit long. Therefore a		SHOULD use only small message ID values, for instance 4 bit long.
	MSB can be used to limit the size of the compression residue.		Therefore, a MSB can be used to limit the size of the compression
			residue.
	In case the Device is a server, client may be located outside of the		In case the Device is a server, the client may be located outside of
	LPWAN area and view the device as a regular device connected to the		the LPWAN area and view the Device as a regular device connected to
	internet. The client will generate Message ID using the 16 bits		the internet. The client will generate Message ID using the 16 bits
	space offered by this field. A CoAP proxy can be set before the SCHC		space offered by this field. A CoAP proxy can be set before the SCHC
	C/D to reduce the value of the Message ID, to allow its compression		C/D to reduce the value of the Message ID, to allow its compression
	with the MSB matching operator and LSB CDA.		with the MSB matching operator and LSB CDA.
	4.5. CoAP Token fields		4.5. CoAP Token fields
	Token is defined through two CoAP fields, Token Length in the		Token is defined through two CoAP fields, Token Length in the
	mandatory header and Token Value directly following the mandatory		mandatory header and Token Value directly following the mandatory
	CoAP header.		CoAP header.
	Token Length is processed as any protocol field. If the value		Token Length is processed as any protocol field. If the value
	remains the same during all the transaction, the size can be stored		remains the same during all the transaction, the size can be stored
	in the context and elided during the transmission. Otherwise it will		in the context and elided during the transmission. Otherwise, it
	have to the send as a compression residue.		will have to the sent as a compression residue.
	Token Value size should not be defined directly in the rule in the		Token Value size cannot be defined directly in the rule in the Field
	Field Length (FL). Instead a specific function designed as "TKL"		Length (FL). Instead, a specific function designated as "TKL" MUST
	must be used and length do not have to the sent with the residue.		be used and length does not have to the sent with the residue.
	During the decompression, this function returns the value contained		During the decompression, this function returns the value contained
	in the Token Length field.		in the Token Length field.
	5. CoAP options		5. CoAP options
	5.1. CoAP Content and Accept options.		5.1. CoAP Content and Accept options.
	These field are both unidirectional and must not be set to		These fields are both unidirectional and MUST NOT be set to
	bidirectional in a rule entry.		bidirectional in a rule entry.
	If single value is expected by the client, it can be stored in the TV		If a single value is expected by the client, it can be stored in the
	and elided during the transmission. Otherwise, if several possible		TV and elided during the transmission. Otherwise, if several
	values are expected by the client, a matching-list should be used to		possible values are expected by the client, a matching-list SHOULD be
	limit the size of the residue. If is not possible, the value has to		used to limit the size of the residue. If is not possible, the value
	be sent as a residue (fixed or variable length).		has to be sent as a residue (fixed or variable length).
	5.2. CoAP option Max-Age field, CoAP option Uri-Host and Uri-Port		5.2. CoAP option Max-Age field, CoAP option Uri-Host and Uri-Port
	fields		fields
	This field is unidirectional and must not be set to bidirectional in		These fields is unidirectional and MUST NOT be set to bidirectional
	a rule entry. It is used only by the server to inform of the caching		in a rule entry. It is used only by the server to inform of the
	duration and is never found in client requests.		caching duration and is never found in client requests.
	If the duration is known by both ends, value can be elided on the		If the duration is known by both ends, the value can be elided on the
	LPWAN.		LPWAN.
	A matching list can be used if some well-known values are defined.		A matching list can be used if some well-known values are defined.
	Otherwise these options should be sent as a residue (fixed or		Otherwise these options SHOULD be sent as a residue (fixed or
	variable length).		variable length).
	5.3. CoAP option Uri-Path and Uri-Query fields		5.3. CoAP option Uri-Path and Uri-Query fields
	This fields are unidirectional and must not be set to bidirectional		These fields are unidirectional and MUST NOT be set to bidirectional
	in a rule entry. They are used only by the client to access to a		in a rule entry. They are used only by the client to access a
	specific resource and are never found in server responses.		specific resource and are never found in server responses.
	Uri-Path and Uri-Query elements are a repeatable options, the Field		Uri-Path and Uri-Query elements are a repeatable options, the Field
	Position (FP) gives the position in the path.		Position (FP) gives the position in the path.
	A Mapping list can be used to reduce size of variable Paths or		A Mapping list can be used to reduce the size of variable Paths or
	Queries. In that case, to optimize the compression, several elements		Queries. In that case, to optimize the compression, several elements
	can be regrouped into a single entry. Numbering of elements do not		can be regrouped into a single entry. Numbering of elements do not
	change, MO comparison is set with the first element of the matching.		change, MO comparison is set with the first element of the matching.
	FID FL FP DI TV MO CDA		FID FL FP DI TV MO CDA
	URI-Path 1 up ["/a/b", equal not-sent		URI-Path 1 up ["/a/b", equal not-sent
	"/c/d"]		"/c/d"]
	URI-Path 3 up ignore value-sent		URI-Path 3 up ignore value-sent
	Figure 2: complex path example		Figure 2: complex path example
	In Figure 2 a single bit residue can be used to code one of the 2		In Figure 2 a single bit residue can be used to code one of the 2
	paths. If regrouping was not allowed, a 2 bits residue is needed.		paths. If regrouping were not allowed, a 2 bits residue would be
			needed.
	5.3.1. Variable length Uri-Path and Uri-Query		5.3.1. Variable length Uri-Path and Uri-Query
	When the length is known at the rule creation, the Field Length must		When the length is not known at the rule creation, the Field Length
	be set to variable, and the unit is set to bytes.		SHOULD be set to variable, and the unit is set to bytes.
	The MSB MO can be apply to a Uri-Path or Uri-Query element. Since		The MSB MO can be applied to a Uri-Path or Uri-Query element. Since
	MSB value is given in bit, the size must always be a multiple of 8		MSB value is given in bit, the size MUST always be a multiple of 8
	bits and the LSB CDA must not carry any value.		bits.
	The length sent at the beginning of a variable length residue		The length sent at the beginning of a variable length residue
	indicates the size of the LSB in bytes.		indicates the size of the LSB in bytes.
	For instance for a CoMi path /c/X6?k="eth0" the rule can be set to:		For instance for a CORECONF path /c/X6?k="eth0" the rule can be set
			to:
	FID FL FP DI TV MO CDA		FID FL FP DI TV MO CDA
	URI-Path 1 up "c" equal not-sent		URI-Path 1 up "c" equal not-sent
	URI-Path 2 up ignore value-sent		URI-Path 2 up ignore value-sent
	URI-Query 1 up "k=" MSB (16) LSB		URI-Query 1 up "k=" MSB (16) LSB
	Figure 3: CoMi URI compression		Figure 3: CORECONF URI compression
	Figure 3 shows the parsing and the compression of the URI. where c is		Figure 3 shows the parsing and the compression of the URI, where c is
	not sent. The second element is sent with the length (i.e. 0x2 X 6)		not sent. The second element is sent with the length (i.e. 0x2 X 6)
	followed by the query option (i.e. 0x05 "eth0").		followed by the query option (i.e. 0x05 "eth0").
	5.3.2. Variable number of path or query elements		5.3.2. Variable number of path or query elements
	The number of Uri-path or Uri-Query element in a rule is fixed at the		The number of Uri-path or Uri-Query elements in a rule is fixed at
	rule creation time. If the number varies, several rules should be		the rule creation time. If the number varies, several rules SHOULD
	created to cover all the possibilities. Another possibilities is to		be created to cover all the possibilities. Another possibility is to
	define the length of Uri-Path to variable and send a compression		define the length of Uri-Path to variable and send a compression
	residue with a length of 0 to indicate that this Uri-Path is empty.		residue with a length of 0 to indicate that this Uri-Path is empty.
	This add 4 bits to the compression residue.		This adds 4 bits to the compression residue.
	5.4. CoAP option Size1, Size2, Proxy-URI and Proxy-Scheme fields		5.4. CoAP option Size1, Size2, Proxy-URI and Proxy-Scheme fields
	These fields are unidirectional and must not be set to bidirectional		These fields are unidirectional and MUST NOT be set to bidirectional
	in a rule entry. They are used only by the client to access to a		in a rule entry. They are used only by the client to access a
	specific resource and are never found in server response.		specific resource and are never found in server response.
	If the field value must be sent, TV is not set, MO is set to "ignore"		If the field value has to be sent, TV is not set, MO is set to
	and CDA is set to "value-sent. A mapping can also be used.		"ignore" and CDA is set to "value-sent". A mapping MAY also be used.
	Otherwise the TV is set to the value, MO is set to "equal" and CDA is		Otherwise, the TV is set to the value, MO is set to "equal" and CDA
	set to "not-sent"		is set to "not-sent".
	5.5. CoAP option ETag, If-Match, If-None-Match, Location-Path and		5.5. CoAP option ETag, If-Match, If-None-Match, Location-Path and
	Location-Query fields		Location-Query fields
	These fields are unidirectional.		These fields are unidirectional.
	These fields values cannot be stored in a rule entry. They must		These fields values cannot be stored in a rule entry. They MUST
	always be sent with the compression residues.		always be sent with the compression residues.
	6. Other RFCs		6. Other RFCs
	6.1. Block		6.1. Block
	Block [rfc7959] allows a fragmentation at the CoAP level. SCHC		Block [rfc7959] allows a fragmentation at the CoAP level. SCHC also
	includes also a fragmentation protocol. They are compatible. If a		includes a fragmentation protocol. They are compatible. If a block
	block option is used, its content must be sent as a compression		option is used, its content MUST be sent as a compression residue.
	residue.
	6.2. Observe		6.2. Observe
	[rfc7641] defines the Observe option. The TV is not set, MO is set		[rfc7641] defines the Observe option. The TV is not set, MO is set
	to "ignore" and the CDA is set to "value-sent". SCHC does not limit		to "ignore" and the CDA is set to "value-sent". SCHC does not limit
	the maximum size for this option (3 bytes). To reduce the		the maximum size for this option (3 bytes). To reduce the
	transmission size either the device implementation should limit the		transmission size, either the device implementation MAY limit the
	delta between two consecutive value or a proxy can modify the		delta between two consecutive values, or a proxy can modify the
	incrementation.		increment.
	Since RST message may be sent to inform a server that the client does		Since an RST message may be sent to inform a server that the client
	not require Observe response, a rule must allow the transmission of		does not require Observe response, a rule MUST allow the transmission
	this message.		of this message.
	6.3. No-Response		6.3. No-Response
	[rfc7967] defines an No-Response option limiting the responses made		[rfc7967] defines a No-Response option limiting the responses made by
	by a server to a request. If the value is not known by both ends,		a server to a request. If the value is known by both ends, then TV
	then TV is set to this value, MO is set to "equal" and CDA is set to		is set to this value, MO is set to "equal" and CDA is set to "not-
	"not-sent".		sent".
	Otherwise, if the value is changing over time, TV is not set, MO is		Otherwise, if the value is changing over time, TV is not set, MO is
	set to "ignore" and CDA to "value-sent". A matching list can also be		set to "ignore" and CDA to "value-sent". A matching list can also be
	used to reduce the size.		used to reduce the size.
	6.4. Time Scale		6.4. Time Scale
	Time scale [I-D.toutain-core-time-scale] option allows a client to		The time scale [I-D.toutain-core-time-scale] option allows a client
	inform the server that it is in a slow network and that message ID		to inform the server that it is in a constrained network and that
	should be kept for a duration given by the option.		message ID MUST be kept for a duration given by the option.
	If the value is not known by both ends, then TV is set to this value,		If the value is known by both ends, then TV is set to this value, MO
	MO is set to "equal" and CDA is set to "not-sent".		is set to "equal" and CDA is set to "not-sent".
	Otherwise, if the value is changing over time, TV is not set, MO is		Otherwise, if the value is changing over time, TV is not set, MO is
	set to "ignore" and CDA to "value-sent". A matching list can also be		set to "ignore" and CDA to "value-sent". A matching list can also be
	used to reduce the size.		used to reduce the size.
	6.5. OSCORE		6.5. OSCORE
	OSCORE [I-D.ietf-core-object-security] defines end-to-end protection		OSCORE [I-D.ietf-core-object-security] defines end-to-end protection
	for CoAP messages. This section describes how SCHC rules can be		for CoAP messages. This section describes how SCHC rules can be
	applied to compress OSCORE-protected messages.		applied to compress OSCORE-protected messages.
	skipping to change at page 11, line 46 ¶		skipping to change at page 12, line 4 ¶
	This draft recommends to implement a parser that is able to identify		This draft recommends to implement a parser that is able to identify
	the OSCORE Option and the fields it contains.		the OSCORE Option and the fields it contains.
	Conceptually, it discerns up to 4 distinct pieces of information		Conceptually, it discerns up to 4 distinct pieces of information
	within the OSCORE option: the flag bits, the piv, the kid context,		within the OSCORE option: the flag bits, the piv, the kid context,
	and the kid. It is thus recommended that the parser split the OSCORE		and the kid. It is thus recommended that the parser split the OSCORE
	option into the 4 subsequent fields:		option into the 4 subsequent fields:
	o CoAP OSCORE_flags,		o CoAP OSCORE_flags,
	o CoAP OSCORE_piv,		o CoAP OSCORE_piv,
	o CoAP OSCORE_kidctxt,		o CoAP OSCORE_kidctxt,
	o CoAP OSCORE_kid.		o CoAP OSCORE_kid.
	These fields are superposed on the OSCORE Option format in Figure 4,		These fields are shown superimposed on the OSCORE Option format in
	the CoAP OSCORE_kidctxt field including the size bits s. Their size		Figure 4, the CoAP OSCORE_kidctxt field including the size bits s.
	may be reduced using the MSB matching operator.		Their size SHOULD be reduced using the MSB matching operator.
	7. Examples of CoAP header compression		7. Examples of CoAP header compression
	7.1. Mandatory header with CON message		7.1. Mandatory header with CON message
	In this first scenario, the LPWAN compressor receives from outside		In this first scenario, the LPWAN compressor at the Network Gateway
	client a POST message, which is immediately acknowledged by the		side receives from a client on the Internet a POST message, which is
	Device. For this simple scenario, the rules are described Figure 5.		immediately acknowledged by the Device. For this simple scenario,
			the rules are described Figure 5.
	Rule ID 1		Rule ID 1
	+-------------+--+--+--+------+---------+-------------++------------+		+-------------+--+--+--+------+---------+-------------++------------+
	| Field. |FL|FP|DI|Target| Match | CDA || Sent |		| Field |FL|FP|DI|Target| Match | CDA || Sent |
	| | | | |Value | Opera. | || [bits] |		| | | | |Value | Opera. | || [bits] |
	+-------------+--+--+--+------+---------+-------------++------------+		+-------------+--+--+--+------+---------+-------------++------------+
	|CoAP version | | |bi| 01 |equal |not-sent || |		|CoAP version | | |bi| 01 |equal |not-sent || |
	|CoAP version | | |bi| 01 |equal |not-sent || |		|CoAP version | | |bi| 01 |equal |not-sent || |
	|CoAP Type | | |dw| CON |equal |not-sent || |		|CoAP Type | | |dw| CON |equal |not-sent || |
	|CoAP Type | | |up|[ACK, | | || |		|CoAP Type | | |up|[ACK, | | || |
	| | | | | RST] |match-map|matching-sent|| T |		| | | | | RST] |match-map|matching-sent|| T |
	|CoAP TKL | | |bi| 0 |equal |not-sent || |		|CoAP TKL | | |bi| 0 |equal |not-sent || |
	|CoAP Code | | |bi| ML1 |match-map|matching-sent|| CC CCC |		|CoAP Code | | |bi| ML1 |match-map|matching-sent|| CC CCC |
	|CoAP MID | | |bi| 0000 |MSB(7 ) |LSB(9) || M-ID|		|CoAP MID | | |bi| 0000 |MSB(7 ) |LSB(9) || M-ID|
	skipping to change at page 18, line 32 ¶		skipping to change at page 19, line 5 ¶
	Original msg length: 10		Original msg length: 10
	Figure 11: CoAP CONTENT Response		Figure 11: CoAP CONTENT Response
	The SCHC Rules for the Inner Compression include all fields that are		The SCHC Rules for the Inner Compression include all fields that are
	already present in a regular CoAP message, what is important is the		already present in a regular CoAP message, what is important is the
	order of appearance and inclusion of only those CoAP fields that go		order of appearance and inclusion of only those CoAP fields that go
	into the Plaintext, Figure 12.		into the Plaintext, Figure 12.
	Rule ID 0		Rule ID 0
	+---------------+--+--+-----------+-----------+-----------++------+		<<<<<<< Updated upstream
	| Field |FP|DI| Target | MO | CDA || Sent |		+---------------+--+--+-----------+-----------+-----------++------+
	| | | | Value | | ||[bits]|		| Field |FP|DI| Target | MO | CDA || Sent |
	+---------------+--+--+-----------+-----------+-----------++------+		| | | | Value | | ||[bits]|
	|CoAP Code | |up| 1 | equal |not-sent || |		+---------------+--+--+-----------+-----------+-----------++------+
	|CoAP Code | |dw|[69,132] | match-map |match-sent || c |		|CoAP Code | |up| 1 | equal |not-sent || |
	|CoAP Uri-Path | |up|temperature| equal |not-sent || |		|CoAP Code | |dw|[69,132] | match-map |match-sent || c |
	|COAP Option-End| |dw| 0xFF | equal |not-sent || |		|CoAP Uri-Path | |up|temperature| equal |not-sent || |
	+---------------+--+--+-----------+-----------+-----------++------+		|COAP Option-End| |dw| 0xFF | equal |not-sent || |
			+---------------+--+--+-----------+-----------+-----------++------+
			=======
			+----------------+--+--+-----------+-----------+-----------++--------+
			| Field |FP|DI| Target | MO | CDA || Sent |
			| | | | Value | | || [bits] |
			+----------------+--+--+-----------+-----------+-----------++--------+
			|CoAP Code | |up| 1 | equal |not-sent || |
			|CoAP Code | |dw|[69,132] | match-map |match-sent || c |
			|CoAP Uri-Path | |up|temperature| equal |not-sent || |
			|COAP Option-End | |dw| 0xFF | equal |not-sent || |
			+----------------+--+--+-----------+-----------+-----------++--------+
			>>>>>>> Stashed changes
	Figure 12: Inner SCHC Rules		Figure 12: Inner SCHC Rules
	Figure 13 shows the Plaintext obtained for our example GET Request		Figure 13 shows the Plaintext obtained for our example GET Request
	and follows the process of Inner Compression and Encryption until we		and follows the process of Inner Compression and Encryption until we
	end up with the Payload to be added in the outer OSCORE Message.		end up with the Payload to be added in the outer OSCORE Message.
	In this case the original message has no payload and its resulting		In this case the original message has no payload and its resulting
	Plaintext can be compressed up to only 1 byte (size of the Rule ID).		Plaintext can be compressed up to only 1 byte (size of the Rule ID).
	The AEAD algorithm preserves this length in its first output, but		The AEAD algorithm preserves this length in its first output, but
	also yields a fixed-size tag which cannot be compressed and must be		also yields a fixed-size tag which cannot be compressed and has to be
	included in the OSCORE message. This translates into an overhead in		included in the OSCORE message. This translates into an overhead in
	total message length, which limits the amount of compression that can		total message length, which limits the amount of compression that can
	be achieved and plays into the cost of adding security to the		be achieved and plays into the cost of adding security to the
	exchange.		exchange.
	________________________________________________________		________________________________________________________
	| |		| |
	| OSCORE Plaintext |		| OSCORE Plaintext |
	| |		| |
	| 0x01bb74656d7065726174757265 (13 bytes) |		| 0x01bb74656d7065726174757265 (13 bytes) |
	skipping to change at page 20, line 7 ¶		skipping to change at page 20, line 48 ¶
	| encrypted_plaintext = 0xa2 (1 byte) |		| encrypted_plaintext = 0xa2 (1 byte) |
	| tag = 0xc54fe1b434297b62 (8 bytes) |		| tag = 0xc54fe1b434297b62 (8 bytes) |
	| |		| |
	| ciphertext = 0xa2c54fe1b434297b62 (9 bytes) |		| ciphertext = 0xa2c54fe1b434297b62 (9 bytes) |
	|_________________________________________________|		|_________________________________________________|
	Figure 13: Plaintext compression and encryption for GET Request		Figure 13: Plaintext compression and encryption for GET Request
	In Figure 14 we repeat the process for the example CONTENT Response.		In Figure 14 we repeat the process for the example CONTENT Response.
	In this case the misalignment produced by the compression residue (1		In this case the misalignment produced by the compression residue (1
	bit) makes it so that 7 bits of padding must be applied after the		bit) makes it so that 7 bits of padding have to be applied after the
	payload, resulting in a compressed Plaintext that is the same size as		payload, resulting in a compressed Plaintext that is the same size as
	before compression. This misalignment also causes the hexcode from		before compression. This misalignment also causes the hexcode from
	the payload to differ from the original, even though it has not been		the payload to differ from the original, even though it has not been
	compressed. On top of this, the overhead from the tag bytes is		compressed. On top of this, the overhead from the tag bytes is
	incurred as before.		incurred as before.
	________________________________________________________		________________________________________________________
	| |		| |
	| OSCORE Plaintext |		| OSCORE Plaintext |
	| |		| |
	skipping to change at page 21, line 49 ¶		skipping to change at page 22, line 4 ¶
	v		v
	_________________________________________________________		_________________________________________________________
	| |		| |
	| encrypted_plaintext = 0x10c6d7c26cc1 (6 bytes) |		| encrypted_plaintext = 0x10c6d7c26cc1 (6 bytes) |
	| tag = 0xe9aef3f2461e0c29 (8 bytes) |		| tag = 0xe9aef3f2461e0c29 (8 bytes) |
	| |		| |
	| ciphertext = 0x10c6d7c26cc1e9aef3f2461e0c29 (14 bytes) |		| ciphertext = 0x10c6d7c26cc1e9aef3f2461e0c29 (14 bytes) |
	|_________________________________________________________|		|_________________________________________________________|
	Figure 14: Plaintext compression and encryption for CONTENT Response		Figure 14: Plaintext compression and encryption for CONTENT Response
			The Outer SCHC Rules (Figure 17) MUST process the OSCORE Options
	The Outer SCHC Rules (Figure 17) must process the OSCORE Options
	fields. In Figure 15 and Figure 16 we show a dump of the OSCORE		fields. In Figure 15 and Figure 16 we show a dump of the OSCORE
	Messages generated from our example messages once they have been		Messages generated from our example messages once they have been
	provided with the Inner Compressed Ciphertext in the payload. These		provided with the Inner Compressed Ciphertext in the payload. These
	are the messages that are to go through Outer SCHC Compression.		are the messages that are to go through Outer SCHC Compression.
	Protected message:		Protected message:
	==================		==================
	0x4102000182d7080904636c69656e74ffa2c54fe1b434297b62		0x4102000182d7080904636c69656e74ffa2c54fe1b434297b62
	(25 bytes)		(25 bytes)
	skipping to change at page 24, line 5 ¶		skipping to change at page 24, line 5 ¶
	certain options.		certain options.
	The piv field lends itself to having a number of bits masked off with		The piv field lends itself to having a number of bits masked off with
	MO MSB and CDA LSB. This could prove useful in applications where		MO MSB and CDA LSB. This could prove useful in applications where
	the message frequency is low such as that found in LPWAN		the message frequency is low such as that found in LPWAN
	technologies. Note that compressing the sequence numbers effectively		technologies. Note that compressing the sequence numbers effectively
	reduces the maximum amount of sequence numbers that can be used in an		reduces the maximum amount of sequence numbers that can be used in an
	exchange. Once this amount is exceeded, the SCHC Context would need		exchange. Once this amount is exceeded, the SCHC Context would need
	to be re-established.		to be re-established.
	The size s included in the kid context field may be masked off with		The size s included in the kid context field MAY be masked off with
	CDA MSB. The rest of the field could have additional bits masked		CDA MSB. The rest of the field could have additional bits masked
	off, or have the whole field be fixed with MO equal and CDA not-sent.		off, or have the whole field be fixed with MO equal and CDA not-sent.
	The same holds for the kid field.		The same holds for the kid field.
	Figure 17 shows a possible set of Outer Rules to compress the Outer		Figure 17 shows a possible set of Outer Rules to compress the Outer
	Header.		Header.
	Rule ID 0		Rule ID 0
	+-------------------+--+--+--------------+--------+---------++------+		<<<<<<< Updated upstream
	| Field |FP|DI| Target | MO | CDA || Sent |		+-------------------+--+--+--------------+--------+---------++------+
	| | | | Value | | ||[bits]|		| Field |FP|DI| Target | MO | CDA || Sent |
	+-------------------+--+--+--------------+--------+---------++------+		| | | | Value | | ||[bits]|
	|CoAP version | |bi| 01 |equal |not-sent || |		+-------------------+--+--+--------------+--------+---------++------+
	|CoAP Type | |up| 0 |equal |not-sent || |		|CoAP version | |bi| 01 |equal |not-sent || |
	|CoAP Type | |dw| 2 |equal |not-sent || |		|CoAP Type | |up| 0 |equal |not-sent || |
	|CoAP TKL | |bi| 1 |equal |not-sent || |		|CoAP Type | |dw| 2 |equal |not-sent || |
	|CoAP Code | |up| 2 |equal |not-sent || |		|CoAP TKL | |bi| 1 |equal |not-sent || |
	|CoAP Code | |dw| 68 |equal |not-sent || |		|CoAP Code | |up| 2 |equal |not-sent || |
	|CoAP MID | |bi| 0000 |MSB(12) |LSB ||MMMM |		|CoAP Code | |dw| 68 |equal |not-sent || |
	|CoAP Token | |bi| 0x80 |MSB(5) |LSB ||TTT |		|CoAP MID | |bi| 0000 |MSB(12) |LSB ||MMMM |
	|CoAP OSCORE_flags | |up| 0x09 |equal |not-sent || |		|CoAP Token | |bi| 0x80 |MSB(5) |LSB ||TTT |
	|CoAP OSCORE_piv | |up| 0x00 |MSB(4) |LSB ||PPPP |		|CoAP OSCORE_flags | |up| 0x09 |equal |not-sent || |
	|COAP OSCORE_kid | |up|0x636c69656e70|MSB(52) |LSB ||KKKK |		|CoAP OSCORE_piv | |up| 0x00 |MSB(4) |LSB ||PPPP |
	|COAP OSCORE_kidctxt| |bi| b'' |equal |not-sent || |		|COAP OSCORE_kid | |up|0x636c69656e70|MSB(52) |LSB ||KKKK |
	|CoAP OSCORE_flags | |dw| b'' |equal |not-sent || |		|COAP OSCORE_kidctxt| |bi| b'' |equal |not-sent || |
	|CoAP OSCORE_piv | |dw| b'' |equal |not-sent || |		|CoAP OSCORE_flags | |dw| b'' |equal |not-sent || |
	|CoAP OSCORE_kid | |dw| b'' |equal |not-sent || |		|CoAP OSCORE_piv | |dw| b'' |equal |not-sent || |
	|COAP Option-End | |dw| 0xFF |equal |not-sent || |		|CoAP OSCORE_kid | |dw| b'' |equal |not-sent || |
	+-------------------+--+--+--------------+--------+---------++------+		|COAP Option-End | |dw| 0xFF |equal |not-sent || |
			+-------------------+--+--+--------------+--------+---------++------+
			=======
			+-------------------+--+--+--------------+---------+-----------++--------+
			| Field |FP|DI| Target | MO | CDA || Sent |
			| | | | Value | | || [bits] |
			+-------------------+--+--+--------------+---------+-----------++--------+
			|CoAP version | |bi| 01 |equal |not-sent || |
			|CoAP Type | |up| 0 |equal |not-sent || |
			|CoAP Type | |dw| 2 |equal |not-sent || |
			|CoAP TKL | |bi| 1 |equal |not-sent || |
			|CoAP Code | |up| 2 |equal |not-sent || |
			|CoAP Code | |dw| 68 |equal |not-sent || |
			|CoAP MID | |bi| 0000 |MSB(12) |LSB ||MMMM |
			|CoAP Token | |bi| 0x80 |MSB(5) |LSB ||TTT |
			|CoAP OSCORE_flags | |up| 0x09 |equal |not-sent || |
			|CoAP OSCORE_piv | |up| 0x00 |MSB(4) |LSB ||PPPP |
			|COAP OSCORE_kid | |up|0x636c69656e70|MSB(52) |LSB ||KKKK |
			|COAP OSCORE_kidctxt| |bi| b'' |equal |not-sent || |
			|CoAP OSCORE_flags | |dw| b'' |equal |not-sent || |
			|CoAP OSCORE_piv | |dw| b'' |equal |not-sent || |
			|CoAP OSCORE_kid | |dw| b'' |equal |not-sent || |
			|COAP Option-End | |dw| 0xFF |equal |not-sent || |
			+-------------------+--+--+--------------+---------+-----------++--------+
			>>>>>>> Stashed changes
	Figure 17: Outer SCHC Rules		Figure 17: Outer SCHC Rules
	These Outer Rules are applied to the example GET Request and CONTENT		These Outer Rules are applied to the example GET Request and CONTENT
	Response. The resulting messages are shown in Figure 18 and		Response. The resulting messages are shown in Figure 18 and
	Figure 19.		Figure 19.
	Compressed message:		Compressed message:
	==================		==================
	0x001489458a9fc3686852f6c4 (12 bytes)		0x001489458a9fc3686852f6c4 (12 bytes)
	skipping to change at page 26, line 5 ¶		skipping to change at page 27, line 5 ¶
	Compressed msg length: 16 bytes		Compressed msg length: 16 bytes
	Figure 19: SCHC-OSCORE Compressed CONTENT Response		Figure 19: SCHC-OSCORE Compressed CONTENT Response
	For contrast, we compare these results with what would be obtained by		For contrast, we compare these results with what would be obtained by
	SCHC compressing the original CoAP messages without protecting them		SCHC compressing the original CoAP messages without protecting them
	with OSCORE. To do this, we compress the CoAP messages according to		with OSCORE. To do this, we compress the CoAP messages according to
	the SCHC rules in Figure 20.		the SCHC rules in Figure 20.
	Rule ID 1		Rule ID 1
	+---------------+--+--+-----------+---------+-----------++--------+		<<<<<<< Updated upstream
	| Field |FP|DI| Target | MO | CDA || Sent |		+---------------+--+--+-----------+---------+-----------++--------+
	| | | | Value | | || [bits] |		| Field |FP|DI| Target | MO | CDA || Sent |
	+---------------+--+--+-----------+---------+-----------++--------+		| | | | Value | | || [bits] |
	|CoAP version | |bi| 01 |equal |not-sent || |		+---------------+--+--+-----------+---------+-----------++--------+
	|CoAP Type | |up| 0 |equal |not-sent || |		|CoAP version | |bi| 01 |equal |not-sent || |
	|CoAP Type | |dw| 2 |equal |not-sent || |		|CoAP Type | |up| 0 |equal |not-sent || |
	|CoAP TKL | |bi| 1 |equal |not-sent || |		|CoAP Type | |dw| 2 |equal |not-sent || |
	|CoAP Code | |up| 2 |equal |not-sent || |		|CoAP TKL | |bi| 1 |equal |not-sent || |
	|CoAP Code | |dw| [69,132] |equal |not-sent || |		|CoAP Code | |up| 2 |equal |not-sent || |
	|CoAP MID | |bi| 0000 |MSB(12) |LSB ||MMMM |		|CoAP Code | |dw| [69,132] |equal |not-sent || |
	|CoAP Token | |bi| 0x80 |MSB(5) |LSB ||TTT |		|CoAP MID | |bi| 0000 |MSB(12) |LSB ||MMMM |
	|CoAP Uri-Path | |up|temperature|equal |not-sent || |		|CoAP Token | |bi| 0x80 |MSB(5) |LSB ||TTT |
	|COAP Option-End| |dw| 0xFF |equal |not-sent || |		|CoAP Uri-Path | |up|temperature|equal |not-sent || |
	+---------------+--+--+-----------+---------+-----------++--------+		|COAP Option-End| |dw| 0xFF |equal |not-sent || |
			+---------------+--+--+-----------+---------+-----------++--------+
			=======
			+---------------+--+--+-----------+---------+-----------++------------+
			| Field |FP|DI| Target | MO | CDA || Sent |
			| | | | Value | | || [bits] |
			+---------------+--+--+-----------+---------+-----------++------------+
			|CoAP version | |bi| 01 |equal |not-sent || |
			|CoAP Type | |up| 0 |equal |not-sent || |
			|CoAP Type | |dw| 2 |equal |not-sent || |
			|CoAP TKL | |bi| 1 |equal |not-sent || |
			|CoAP Code | |up| 2 |equal |not-sent || |
			|CoAP Code | |dw| [69,132] |equal |not-sent || |
			|CoAP MID | |bi| 0000 |MSB(12) |LSB ||MMMM |
			|CoAP Token | |bi| 0x80 |MSB(5) |LSB ||TTT |
			|CoAP Uri-Path | |up|temperature|equal |not-sent || |
			|COAP Option-End| |dw| 0xFF |equal |not-sent || |
			+---------------+--+--+-----------+---------+-----------++------------+
			>>>>>>> Stashed changes
	Figure 20: SCHC-CoAP Rules (No OSCORE)		Figure 20: SCHC-CoAP Rules (No OSCORE)
	This yields the results in Figure 21 for the Request, and Figure 22		This yields the results in Figure 21 for the Request, and Figure 22
	for the Response.		for the Response.
	Compressed message:		Compressed message:
	==================		==================
	0x0114		0x0114
	0x01 = Rule ID		0x01 = Rule ID
	skipping to change at page 27, line 41 ¶		skipping to change at page 29, line 10 ¶
	10. Acknowledgements		10. Acknowledgements
	Thanks to all the persons that have give us feedback		Thanks to all the persons that have give us feedback
	11. Normative References		11. Normative References
	[I-D.ietf-core-object-security]		[I-D.ietf-core-object-security]
	Selander, G., Mattsson, J., Palombini, F., and L. Seitz,		Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
	"Object Security for Constrained RESTful Environments		"Object Security for Constrained RESTful Environments
	(OSCORE)", draft-ietf-core-object-security-15 (work in		(OSCORE)", draft-ietf-core-object-security-16 (work in
	progress), August 2018.		progress), March 2019.
	[I-D.ietf-lpwan-ipv6-static-context-hc]		[I-D.ietf-lpwan-ipv6-static-context-hc]
	Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and J.		Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and J.
	Zuniga, "LPWAN Static Context Header Compression (SCHC)		Zuniga, "LPWAN Static Context Header Compression (SCHC)
	and fragmentation for IPv6 and UDP", draft-ietf-lpwan-		and fragmentation for IPv6 and UDP", draft-ietf-lpwan-
	ipv6-static-context-hc-18 (work in progress), December		ipv6-static-context-hc-18 (work in progress), December
	2018.		2018.
	[I-D.toutain-core-time-scale]		[I-D.toutain-core-time-scale]
	Minaburo, A. and L. Toutain, "CoAP Time Scale Option",		Minaburo, A. and L. Toutain, "CoAP Time Scale Option",
End of changes. 77 change blocks.
	213 lines changed or deleted		269 lines changed or added
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