The Cryptographic Token Key Initialization Protocol CTKIP

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Title: The Cryptographic Token Key Initialization Protocol CTKIP

1
The Cryptographic Token Key Initialization
Protocol (CT-KIP)

2
CT-KIP Primer

A client-server protocol for initialization and
configuration of cryptographic tokens with shared
keys
Intended for general use within computer and
communications systems employing connected
cryptographic tokens
Objectives are to provide a
Secure and interoperable method of initializing
cryptographic tokens with secret keys
Solution that is easy to administer and scales
well
Solution which does not require private-key
capabilities in tokens, nor the existence of a
public-key infrastructure

3
Current Status

IESG approved Version 1.0 for publication as RFC
Describes a 4-pass protocol for the
initialization of cryptographic tokens with
secret keys. Includes a public-key variant as
well as a shared-key variant.
In December 2005 it was published as OTPS doc,
then re-published as IETF I-D, which is now
draft-nystrom-ct-kip-02
Implementations exist and in production
3rd draft of 1-, 2-pass variant also published as
IETF I-D
draft-nyström-ct-kip-two-pass-01.txt
Relatively stable and broad review solicited
CT-KIP SOAP binding recently published as IETF
I-D
draft-doherty-ct-kip-ws-00.txt
First draft revision is coming
Implementations exist and in production

4
CT-KIP 1, 2, 4-pass Comparison
CT-KIP server
CT-KIP client
Smart Device
5
CT-KIP 1- and 2-pass

New variants introduced to meet the needs of
deployment scenarios with constraints, e.g.,
No direct communication possible between
cryptographic token and CT-KIP server
Network latency
Design limited to existing seeds from legacy
systems
1-, 2-pass CT-KIP are essentially a transport of
key material from CT-KIP server to CT-KIP client
These variants maintain the property that no
other entity than the token and the server will
have access to generated / distributed keys

6
CT-KIP ClientHello Extension
7
CT-KIP ServerFinished Extension

New extension in ServerFinished is used by CT-KIP
server to transfer key to CT-KIP client
Key material is wrapped in tokens public key or
symmetric key
Tokens public key may have been included in
payload of ClientHello
Symmetric key may be a shared secret
Symmetric key may be derived from a passphrase
Extension is applicable to both 1-pass and 2-pass
variants of CT-KIP
Extension could easily be added to support PSKC
defined in draft-vassilev-portable-symmetric-key-c
ontainer-01.txt

8
CT-KIP 1- and 2-pass Profiles
9
Cryptographic properties (all variants)

Key confirmation
In all variants via MAC on exchanged data (and
counter in 1-pass)
Replay protection
In 2- and 4-pass through inclusion of
client-provided data in MAC
Suggested method for 1-pass based on counter
Server authentication
In all variants through MAC in ServerFinished
message when replacing existing key
Protection against MITM
In all variants through use of shared keys,
client certificates, or server public key usage
User authentication
Enabled in all variants through trigger message
Alternative methods rely on draft-doherty-ct-kip-w
s-00
Device authentication
In all variants if based on shared secret key
In 2-pass if device sends a certificate
Alternative methods rely on draft-doherty-ct-kip-w
s-00

10
Bindings (all variants)

SOAP Binding
Present in all variants
Web service interface is defined in
draft-doherty-ct-kip-ws-00
HTTP Binding
Present in all variants
Examples provided
Security Binding
Transport level encryption (e.g., TLS) is not
required for seed protection in all variants
TLS/SSL is required if other parameters/attributes
must be protected in transit