Galileo Open Service Navigation Message Authentication - Revision history

Gema.Cueto: Updated reference ICD/SDD links

2026-04-17T11:47:20Z

Updated reference ICD/SDD links

← Older revision		Revision as of 11:47, 17 April 2026
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	==Introduction to Galileo OS-NMA feature==		==Introduction to Galileo OS-NMA feature==

	Galileo OS-NMA feature consists of digitally signing the [[Galileo Navigation Message \| Open Service Navigation message]] in the E1 band, making use of forty reserved bits (“Reserved 1”) in the Galileo E1B data message (I/NAV) and the Timed Efficient Stream Loss-Tolerant Authentication (TESLA) protocol<ref>I. Fernández-Hernández, V. Rijmen, G. Seco-Granados, J. Simon, I. Rodríguez, and J. David Calle, “A Navi-gation Message Authentication Proposal for the Galileo Open Service,” Navigation, Journal of The Institute of Navigation, vol. 63, no. 1, pp. 85-102</ref>, thus keeping the rest of the navigation message unencrypted<ref name="NMA-SIS">[https://www.~~gsa.~~europa.eu/sites/default/files/~~calls_for_proposals~~/~~annex_1~~-~~rd4~~.pdf Galileo Navigation Message Authentication Specification for Signal-In-Space Testing ~~v1.0~~]</ref> . The use of these reserved bits allows backwards compatibility with older versions of the navigation message ICD.		Galileo OS-NMA feature consists of digitally signing the [[Galileo Navigation Message \| Open Service Navigation message]] in the E1 band, making use of forty reserved bits (“Reserved 1”) in the Galileo E1B data message (I/NAV) and the Timed Efficient Stream Loss-Tolerant Authentication (TESLA) protocol<ref>I. Fernández-Hernández, V. Rijmen, G. Seco-Granados, J. Simon, I. Rodríguez, and J. David Calle, “A Navi-gation Message Authentication Proposal for the Galileo Open Service,” Navigation, Journal of The Institute of Navigation, vol. 63, no. 1, pp. 85-102</ref>, thus keeping the rest of the navigation message unencrypted<ref name="NMA-SIS">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-OSNMA-SIS-ICD_in_force.pdf Galileo OS Navigation Message Authentication Specification for Signal-In-Space Testing]</ref> . The use of these reserved bits allows backwards compatibility with older versions of the navigation message ICD.

	[[File:Galileo_OS_NMA_SIS.png\|500px\|OS-NMA field in I/NAV word <ref name="NMA-SIS"/> \|none\|thumb]]		[[File:Galileo_OS_NMA_SIS.png\|500px\|OS-NMA field in I/NAV word <ref name="NMA-SIS"/> \|none\|thumb]]

Gema.Cueto at 10:33, 21 May 2021

2021-05-21T10:33:53Z

← Older revision		Revision as of 10:33, 21 May 2021
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	Galileo OS-NMA (Open Service – Navigation Message Authentication) represents an [[GNSS Authentication and encryption \| authentication]] mechanism that allows a GNSS receiver to verify the authenticity of the GNSS information and of the entity transmitting it, to ensure that it comes from a trusted source. Authentication is an intrinsic GNSS capability remaining internal to the GNSS receiver, without any new interfaces to the avionics.		Galileo OS-NMA (Open Service – Navigation Message Authentication) represents an [[GNSS Authentication and encryption \| authentication]] mechanism that allows a GNSS receiver to verify the authenticity of the GNSS information and of the entity transmitting it, to ensure that it comes from a trusted source. Authentication is an intrinsic GNSS capability remaining internal to the GNSS receiver, without any new interfaces to the avionics.

	Galileo OS-NMA will be a free-of-charge service which will become available in the near-term evolutions of the Galileo Full Operational capability (FOC), potentially for 2022-2023. On November 2020, Galileo satellites started the transmission of authentication data for testing purposes~~. Testing will continue during the next months. Upon successful completion of the internal testing phase, a public observation phase will begin.~~<ref>[https://www.gsa.europa.eu/newsroom/news/tests-galileo-osnma-underway Tests of Galileo OSNMA underway(europa.eu)]</ref>		Galileo OS-NMA will be a free-of-charge service which will become available in the near-term evolutions of the Galileo Full Operational capability (FOC), potentially for 2022-2023. On November 2020, Galileo satellites started the transmission of authentication data for testing purposes<ref>[https://www.gsa.europa.eu/newsroom/news/tests-galileo-osnma-underway Tests of Galileo OSNMA underway(europa.eu)]</ref>. From 2021 Galileo OS-NMA will start a public observation phase before the official provision of Galileo OS-NMA as part of the Galileo services<ref name="OS-NMA">[https://www.euspa.europa.eu/simplecount_pdf/tracker?file=uploads/ucp_2020_open_service_navigation_message_authentication_0.pdf Galileo OS-NMA roadmap]</ref>.

	==Introduction to Galileo OS-NMA feature==		==Introduction to Galileo OS-NMA feature==

Gema.Cueto: /* Authentication based on Galileo OS-NMA */

2021-02-17T07:46:32Z

Authentication based on Galileo OS-NMA

← Older revision		Revision as of 07:46, 17 February 2021
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	The way in which authentication based on Galileo OS-NMA works can be summarized as follows:		The way in which authentication based on Galileo OS-NMA works can be summarized as follows:
	* The receiver demodulates the navigation data and a Message Authentication Code (MAC) that authenticates the plaintext navigation message.		* The receiver demodulates the navigation data and a Message Authentication Code (MAC) that authenticates the plaintext navigation message.
	* The receiver demodulates the key required to authenticate the MAC. This key is broadcast by the system with some delay with respect the associated MAC.		* The receiver demodulates the key required to authenticate the MAC. This key is broadcast by the system with some delay with respect the associated MAC.
	* The receiver authenticates the key with a previous key from the chain that is considered authentic or from the root key. As explained before, this key is part of a pre-generated one-way chain whose root is public, and which is transmitted in reverse order with respect to its generation		* The receiver authenticates the key with a previous key from the chain that is considered authentic or from the root key. As explained before, this key is part of a pre-generated one-way chain whose root is public, and which is transmitted in reverse order with respect to its generation
	* The receiver re-generates the MAC key with the data, which should match the previously received MAC.		* The receiver re-generates the MAC key with the data, which should match the previously received MAC.


	A summary of the proposed Galileo OS-NMA architecture is shown below.		A summary of the proposed Galileo OS-NMA architecture is shown below.

Gema.Cueto at 07:44, 17 February 2021

2021-02-17T07:44:05Z

← Older revision		Revision as of 07:44, 17 February 2021
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	==Introduction to Galileo OS-NMA feature==		==Introduction to Galileo OS-NMA feature==

	Galileo OS-NMA feature consists of digitally signing the [[Galileo Navigation Message \| Open Service Navigation message]] in the E1 band, making use of forty reserved bits (“Reserved 1”) in the Galileo E1B data message (I/NAV) and the Timed Efficient Stream Loss-Tolerant Authentication (~~TESTA~~) protocol<ref>I. Fernández-Hernández, V. Rijmen, G. Seco-Granados, J. Simon, I. Rodríguez, and J. David Calle, “A Navi-gation Message Authentication Proposal for the Galileo Open Service,” Navigation, Journal of The Institute of Navigation, vol. 63, no. 1, pp. 85-102</ref>, thus keeping the rest of the navigation message unencrypted<ref name="NMA-SIS">[https://www.gsa.europa.eu/sites/default/files/calls_for_proposals/annex_1-rd4.pdf Galileo Navigation Message Authentication Specification for Signal-In-Space Testing v1.0]</ref> . The use of these reserved bits allows backwards compatibility with older versions of the navigation message ICD.		Galileo OS-NMA feature consists of digitally signing the [[Galileo Navigation Message \| Open Service Navigation message]] in the E1 band, making use of forty reserved bits (“Reserved 1”) in the Galileo E1B data message (I/NAV) and the Timed Efficient Stream Loss-Tolerant Authentication (TESLA) protocol<ref>I. Fernández-Hernández, V. Rijmen, G. Seco-Granados, J. Simon, I. Rodríguez, and J. David Calle, “A Navi-gation Message Authentication Proposal for the Galileo Open Service,” Navigation, Journal of The Institute of Navigation, vol. 63, no. 1, pp. 85-102</ref>, thus keeping the rest of the navigation message unencrypted<ref name="NMA-SIS">[https://www.gsa.europa.eu/sites/default/files/calls_for_proposals/annex_1-rd4.pdf Galileo Navigation Message Authentication Specification for Signal-In-Space Testing v1.0]</ref> . The use of these reserved bits allows backwards compatibility with older versions of the navigation message ICD.

	[[File:Galileo_OS_NMA_SIS.png\|500px\|OS-NMA field in I/NAV word <ref name="NMA-SIS"/> \|none\|thumb]]		[[File:Galileo_OS_NMA_SIS.png\|500px\|OS-NMA field in I/NAV word <ref name="NMA-SIS"/> \|none\|thumb]]
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	==TESLA protocol==		==TESLA protocol==

	Galileo OS-NMA authentication capability is based on the use of ~~TESTA~~ protocol. One of the greatest advantages of this protocol is that it requires low bandwidth to transmit the authentication information, together with a tolerance to data loss in case a message is lost.		Galileo OS-NMA authentication capability is based on the use of TESLA protocol. One of the greatest advantages of this protocol is that it requires low bandwidth to transmit the authentication information, together with a tolerance to data loss in case a message is lost.

	The main idea of TESLA protocol is that the key used in the authentication process belongs to a chain generated using a one-way function F, also called hash function. The chain starts with a secret seed key; and each element of the chain can be constructed by hashing the previous element. This one-way function cannot be used to predict keys. This implies that the receiver must possess some information (the root key) certified as correct independently from the information sent through the Signal in Space.		The main idea of TESLA protocol is that the key used in the authentication process belongs to a chain generated using a one-way function F, also called hash function. The chain starts with a secret seed key; and each element of the chain can be constructed by hashing the previous element. This one-way function cannot be used to predict keys. This implies that the receiver must possess some information (the root key) certified as correct independently from the information sent through the Signal in Space.

Gema.Cueto: /* TESTA protocol */

2021-02-16T08:02:38Z

TESTA protocol

← Older revision		Revision as of 08:02, 16 February 2021
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	* The MACK section (next 32 bits) contain the MACs and associated keys, delivered later.		* The MACK section (next 32 bits) contain the MACs and associated keys, delivered later.

	==~~TESTA~~ protocol==		==TESLA protocol==

	Galileo OS-NMA authentication capability is based on the use of TESTA protocol. One of the greatest advantages of this protocol is that it requires low bandwidth to transmit the authentication information, together with a tolerance to data loss in case a message is lost.		Galileo OS-NMA authentication capability is based on the use of TESTA protocol. One of the greatest advantages of this protocol is that it requires low bandwidth to transmit the authentication information, together with a tolerance to data loss in case a message is lost.

Gema.Cueto: /* Introduction to Galileo OS-NMA feature */

2021-02-16T08:02:17Z

Introduction to Galileo OS-NMA feature

← Older revision		Revision as of 08:02, 16 February 2021
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	==Introduction to Galileo OS-NMA feature==		==Introduction to Galileo OS-NMA feature==

	Galileo OS-NMA feature consists of digitally signing the Open Service Navigation message in the E1 band, making use of forty reserved bits (“Reserved 1”) in the Galileo E1B data message (I/NAV) and the Timed Efficient Stream Loss-Tolerant Authentication (TESTA) protocol<ref>I. Fernández-Hernández, V. Rijmen, G. Seco-Granados, J. Simon, I. Rodríguez, and J. David Calle, “A Navi-gation Message Authentication Proposal for the Galileo Open Service,” Navigation, Journal of The Institute of Navigation, vol. 63, no. 1, pp. 85-102</ref>, thus keeping the rest of the navigation message unencrypted<ref name="NMA-SIS">[https://www.gsa.europa.eu/sites/default/files/calls_for_proposals/annex_1-rd4.pdf Galileo Navigation Message Authentication Specification for Signal-In-Space Testing v1.0]</ref> . The use of these reserved bits allows backwards compatibility with older versions of the navigation message ICD.		Galileo OS-NMA feature consists of digitally signing the [[Galileo Navigation Message \| Open Service Navigation message]] in the E1 band, making use of forty reserved bits (“Reserved 1”) in the Galileo E1B data message (I/NAV) and the Timed Efficient Stream Loss-Tolerant Authentication (TESTA) protocol<ref>I. Fernández-Hernández, V. Rijmen, G. Seco-Granados, J. Simon, I. Rodríguez, and J. David Calle, “A Navi-gation Message Authentication Proposal for the Galileo Open Service,” Navigation, Journal of The Institute of Navigation, vol. 63, no. 1, pp. 85-102</ref>, thus keeping the rest of the navigation message unencrypted<ref name="NMA-SIS">[https://www.gsa.europa.eu/sites/default/files/calls_for_proposals/annex_1-rd4.pdf Galileo Navigation Message Authentication Specification for Signal-In-Space Testing v1.0]</ref> . The use of these reserved bits allows backwards compatibility with older versions of the navigation message ICD.

	[[File:Galileo_OS_NMA_SIS.png\|500px\|OS-NMA field in I/NAV word <ref name="NMA-SIS"/> \|none\|thumb]]		[[File:Galileo_OS_NMA_SIS.png\|500px\|OS-NMA field in I/NAV word <ref name="NMA-SIS"/> \|none\|thumb]]

Gema.Cueto at 08:00, 16 February 2021

2021-02-16T08:00:12Z

← Older revision		Revision as of 08:00, 16 February 2021
Line 10:		Line 10:
	Galileo OS-NMA (Open Service – Navigation Message Authentication) represents an [[GNSS Authentication and encryption \| authentication]] mechanism that allows a GNSS receiver to verify the authenticity of the GNSS information and of the entity transmitting it, to ensure that it comes from a trusted source. Authentication is an intrinsic GNSS capability remaining internal to the GNSS receiver, without any new interfaces to the avionics.		Galileo OS-NMA (Open Service – Navigation Message Authentication) represents an [[GNSS Authentication and encryption \| authentication]] mechanism that allows a GNSS receiver to verify the authenticity of the GNSS information and of the entity transmitting it, to ensure that it comes from a trusted source. Authentication is an intrinsic GNSS capability remaining internal to the GNSS receiver, without any new interfaces to the avionics.

	Galileo OS-NMA will be a free-of-charge service which will become available in the near-term evolutions of the Galileo Full Operational capability (FOC), potentially for 2022-2023.		Galileo OS-NMA will be a free-of-charge service which will become available in the near-term evolutions of the Galileo Full Operational capability (FOC), potentially for 2022-2023. On November 2020, Galileo satellites started the transmission of authentication data for testing purposes. Testing will continue during the next months. Upon successful completion of the internal testing phase, a public observation phase will begin.<ref>[https://www.gsa.europa.eu/newsroom/news/tests-galileo-osnma-underway Tests of Galileo OSNMA underway(europa.eu)]</ref>

	==Introduction to Galileo OS-NMA feature==		==Introduction to Galileo OS-NMA feature==

Gema.Cueto: /* Authentication based on Galileo OS-NMA */

2021-01-29T10:54:15Z

Authentication based on Galileo OS-NMA

← Older revision		Revision as of 10:54, 29 January 2021
Line 34:		Line 34:
	The way in which authentication based on Galileo OS-NMA works can be summarized as follows:		The way in which authentication based on Galileo OS-NMA works can be summarized as follows:
	* The receiver demodulates the navigation data and a Message Authentication Code (MAC) that authenticates the plaintext navigation message.		* The receiver demodulates the navigation data and a Message Authentication Code (MAC) that authenticates the plaintext navigation message.
	* The key required to authenticate the MAC is broadcast by the system with some delay.		* The receiver demodulates the key required to authenticate the MAC. This key is broadcast by the system with some delay with respect the associated MAC.
	* The receiver demodulates the ~~key~~.
	* The receiver authenticates the key with a previous key from the chain that is considered authentic or from the root key. As explained before, this key is part of a pre-generated one-way chain whose root is public, and which is transmitted in reverse order with respect to its generation		* The receiver authenticates the key with a previous key from the chain that is considered authentic or from the root key. As explained before, this key is part of a pre-generated one-way chain whose root is public, and which is transmitted in reverse order with respect to its generation
	* The receiver re-generates the MAC key with the data, which should match the previously received MAC.		* The receiver re-generates the MAC key with the data, which should match the previously received MAC.

Gema.Cueto: /* Introduction to Galileo OS-NMA feature */

2021-01-29T10:52:36Z

Introduction to Galileo OS-NMA feature

← Older revision		Revision as of 10:52, 29 January 2021
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	The OSNMA field is composed of two parts:		The OSNMA field is composed of two parts:
	* The HKROOT section (first 8 bits) includes the global headers and the Digital Signature Message (DSM.		* The HKROOT section (first 8 bits) includes the global headers and the Digital Signature Message (DSM).
	* The MACK section (next 32 bits) contain the MACs and associated keys, delivered later.		* The MACK section (next 32 bits) contain the MACs and associated keys, delivered later.

Gema.Cueto at 10:51, 29 January 2021

2021-01-29T10:51:56Z

← Older revision		Revision as of 10:51, 29 January 2021
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	}}		}}

	Galileo OS-NMA (Open Service – Navigation Message Authentication) represents an [[~~authentication \|~~ GNSS Authentication and encryption]] mechanism that allows a GNSS receiver to verify the authenticity of the GNSS information and of the entity transmitting it, to ensure that it comes from a trusted source. Authentication is an intrinsic GNSS capability remaining internal to the GNSS receiver, without any new interfaces to the avionics.		Galileo OS-NMA (Open Service – Navigation Message Authentication) represents an [[GNSS Authentication and encryption \| authentication]] mechanism that allows a GNSS receiver to verify the authenticity of the GNSS information and of the entity transmitting it, to ensure that it comes from a trusted source. Authentication is an intrinsic GNSS capability remaining internal to the GNSS receiver, without any new interfaces to the avionics.

	Galileo OS-NMA will be a free-of-charge service which will become available in the near-term evolutions of the Galileo Full Operational capability (FOC), potentially for 2022-2023.		Galileo OS-NMA will be a free-of-charge service which will become available in the near-term evolutions of the Galileo Full Operational capability (FOC), potentially for 2022-2023.