HIP Explained
SMA Demo Team
International Civil Aviation Organization
INFORMATION PAPER
ACP-SWGN13 – IP06 14 APRIL 2007
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Agenda
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• HIP Explained
• Explanation of the Status Display Screens
• Explanation of the Demonstration
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HIP elements
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Host Identity (HI) is public/private key pair:
IP header
Identity defined
by holder of
private key
Public key used
by others
to authenticate
control messages
SHA-1 hash of public key forms a
“Host Identity Tag (HIT)”
- used where 128 bit fields are needed
- self-referential (i.e., HIT can be
securely used instead of HI)
Copyright © 2004 Boeing. All rights reserved.
IPsec (ESP)
Encrypted
transport
header and
payload
HIT is
implied
by the SPI
value in
IPsec header
(i.e. HIP incurs
no per-packet
overhead)
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What problems does HIP solve?
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HIP may admit more elegant solutions to:
• host mobility: Binding Updates for route optimization
automatically and directly authenticated
• host multihoming: Can associate more than one IP
address with a security association
• BGP scaling problem: Multihomed networks may have
hosts with multiple, aliased addresses
• NAT traversal: Changing IP addresses does not break
transport checksums
• IPv4 to IPv6 transition: Ditto
and others...
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HIP deployment issues
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• HIP can be deployed pair-wise, without any
supporting infrastructure (like ssh)
• No changes to routing infrastructure
• Backward compatible with legacy apps
• For more advanced features, some additional
infrastructure will be needed:
• support for new DNS resource record
• support for “rendezvous server” to offload DNS
update loads, and to solve “double-jump” mobility
• HIP-aware NATs and firewalls
• reverse lookup service for HITs
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Background: IPsec
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Responder
Initiator
Keying daemon
( e.g. IKE)
Application
user space
PF_INET
PF_RAW
PF_KEY
Keying daemon
( e.g. IKE)
PF_KEY
PF_RAW
Application
PF_INET
kernel
TCP/IP code
IPsec
Key
engine
Key
engine
TCP/IP code
IPsec
IPsec Security Association (transport mode)
identified by SPI in IPsec header, IP addresses
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Boeing HIP Implementation
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Mainly a user-space daemon (replacing IKE), with minor
kernel and API modifications
• IPv4 and IPv6 Linux kernel 2.6.7
• KAME-derived ipsec-tools package (for Linux 2.6)
• OpenSSL 0.9.7 (cryptographic libraries)
Application
user space
PF_INET
openssl libraries
HIP daemon
(hipd)
PF_RAW
ipsec-tools (setkey)
PF_KEY
kernel
small mods
required
here also
Copyright © 2004 Boeing. All rights reserved.
TCP/IP code
IPsec
APIs extended
slightly
Key
engine
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HIP-enabled security
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Responder
Initiator
Application
user space
PF_INET
HIP handshake
HIP daemon
HIP daemon
PF_RAW
PF_KEY
PF_KEY
PF_RAW
Application
PF_INET
kernel
TCP/IP code
IPsec
Key
engine
Key
engine
TCP/IP code
IPsec
IPsec Security Association (ESP, AH)
identified by SPI in IPsec header (but not IP address!)
Copyright © 2004 Boeing. All rights reserved.
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HIP Handshake
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Initiator
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I1 packet
Simple packet, contains
compressed (hashed)
version of Host Identities
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Responder
Opportunity
for DoS attack
(e.g. TCP SYN
flood)
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HIP Handshake
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Initiator
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I1 packet
Responder
R1 packet
Contains:
1. Diffie-Hellman public value
2. Cookie puzzle
3. Encryption negotiation
4. Responder’s Host Identity
Reply with
stock packet
and cookie
challenge
(No state kept)
Is signed by Responder’s Host Identity
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HIP Handshake
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Initiator
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I1 packet
Responder
R1 packet
I2 packet
1. Solve cookie puzzle
2. Generate key material
Contains:
1. Diffie-Hellman public value
2. Cookie solution
3. Encryption negotiation
4. IPsec SPI
5. (Encrypted) Host Identity
6. (optional) piggybacked data
Is signed by Initiator’s Host Identity
Copyright © 2004 Boeing. All rights reserved.
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HIP Handshake
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Initiator
Responder
I1 packet
R1 packet
I2 packet
R2 packet
Contains:
1. IPsec SPI
2. (option) piggybacked data
1. Validate cookie puzzle
2. Generate key material
3. Install IPsec SA
Is signed by Responder’s Host Identity
Copyright © 2004 Boeing. All rights reserved.
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HIP Handshake
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Initiator
Responder
I1 packet
R1 packet
I2 packet
R2 packet
Install IPsec SA
All further packets in IPsec ESP envelope
(Host Identity is implied by the SPI)
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HIP Readdress
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Readdressee
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Peer
Contains new address and SPI
Is signed by Host Identity
Optional address check
if needed (to prevent
3rd party bombing attacks)
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HIP crypto performance
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• HIP exchange takes less than one second on
same PII-266MHz machines
• Time dominated by DSA signing (therefore, cookie
challenge is important)
• Time spent in various functions (averages):
• Readdressing a host takes less than one second
SHA keymat hashing
Initiator
Responder
Copyright © 2004 Boeing. All rights reserved.
0.08 ms
0.11 ms
DSA signing 3DES crypto Total exchange
450 ms
410 ms
0.53 ms
0.53 ms
950 ms
790 ms
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