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Here are some additional slides from LTE System overview course delivered in September 2012 in Warsaw, Poland. Are you interested in attending top in class LTE/LTE-Advanced courses, please have a look on our course portfolio: http://is-wireless.com/trainings/lte-lte-advanced or contact us directly: [email protected].
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EPS Security
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com
Title
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
E-UTRAN and EPC Authentication and Key Agreement Procedure
MME HSS
First NAS Message (user identity)
Authentication data request (IMSI)
Authentication data response
(authentication vector:
RAND; XRES; CK; IK; AUTN)
Authentication vector calculation
(RAND; XRES; CK; IK; AUTN)
Verifies AUTN
(network authentication)
Calculates RES
User Authentication request
(RAND, AUTN)
User Authentication response
(RES) Compares RES and XRES
(USIM authentication) Calculates CK
and IK
Authentication Vector:
• RAND – random number (one of the input parameters used to generate the other)
• XRES – Expected result used by the network for USIM authentication
• AUTN – authentication token used by the USIM for network authentication
• CK – ciphering key
• IK – integrity key
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com
Title
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
USIM/AuC
UE/HSS
UE/MME
UE/eNB
E-UTRAN and EPC Key Hierarchy and Usage
K
CK, IK
KASME
KeNB/NH
KRRCint KRRCenc KUPenc
KNASint KNASenc
Keys Application of Keys
eNB
MME SGW
Integrity
Encryption
Integrity
Encryption Encryption
KNASint
KNASenc
KRRCint
KRRCenc KUPenc
RRC messages
NAS messages
User IP packets
Stored Key
Used for Derivation
Key
Used for Encryption
Key
derivation
Hom
e d
om
ain
specific
keys
EP
C s
pecific
keys
EU
TR
AN
specific
keys
Encapsulated NAS messages
(double protection)
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com
Title
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
E-UTRAN and EPC Derivation of Security Keys
MME HSS eNB eNB
Target at HO
KDF
CK, IK
SN id
KASME
KDF KDF
KDF NAS
UL Count
NAS-int-alg,
Alg-ID NAS-enc-alg,
Alg-ID
KNASint KNASenc
KDF KDF
RRC-int-alg,
Alg-ID RRC-enc-alg,
Alg-ID
KRRCint KRRCenc
KDF
KUPenc
UP-enc-alg,
Alg-ID
KDF KeNB* KeNB
KDF
KeNB source
PHY cell ID/EARFCN DL target
NH
KUPenc
KRRCenc
KRRCint
Source
KeNB
NH
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com
Title
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
E-UTRAN and EPC Ciphering and Integrity Algorithms
Ciphering EEA (EPS Encryption Algorithm)
Integrity EIA (EPS Integrity Algorithm)
Sym
etr
ic c
rypto
gra
phy
Alg
orith
m c
an b
e c
hanged o
nly
aft
er
HO
EEA (Snow3G or AES)
Transmitter Receiver
Count Bearer Direction Length
Key
Keystream
Original stream Ciphertext stream
EEA (Snow3G or AES)
Count Bearer Direction Length
Key
Keystream
Original stream
EIA (Snow3G or AES)
Transmitter Receiver
Count Message Direction Bearer
Key
MAC-I/NAS-MAC
EIA (Snow3G or AES)
Count Message Direction Bearer
Key
XMAC-I/XNAS-MAC
MAC-I/NAS-MAC
Compare
Protects data streams from
being received by the 3rd party
Allows the receiver to detect packet
insertion or replacement
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com
Title
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
Backup slides
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com
Title
Copyright by Innovative Solutions. All rights reserved. www.is-wireless.com Copyright by IS-Wireless. All rights reserved. www.is-wireless.com
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