3 research outputs found
Some Theoretical Conditions for Menezes--Qu--Vanstone Key Agreement to Provide Implicit Key Authentication
Menezes--Qu--Vanstone key agreement (MQV) is intended to provide implicit key authentication (IKA) and several other security objectives. MQV is approved and specified in five standards.
This report focuses on the IKA of two-pass MQV, without key confirmation. Arguably, implicit key authentication is the most essential security objective in authenticated key agreement. The report examines various necessary or sufficient formal conditions under which MQV may provide IKA.
Incidentally, this report defines, relies on, and inter-relates various conditions on the key deriviation function and Diffie--Hellman groups. While it should be expected that most such definitions and results are already well-known, a reader interested in these topics may be interested in this report as a kind of review, even if they have no interest in MQV whatsoever
Key establishment --- security models, protocols and usage
Key establishment is the process whereby two or more parties derive a shared
secret, typically used for subsequent confidential communication. However,
identifying the exact security requirements for key establishment protocols is
a non-trivial task. This thesis compares, extends and merges existing security
definitions and models for key establishment protocols.
The primary focus is on two-party key agreement schemes in the public-key
setting. On one hand new protocols are proposed and analyzed in the existing
Canetti-Krawzcyk model. On the other hand the thesis develops a security model
and novel definition that capture the essential security attributes of the
standardized Unified Model key agreement protocol. These analyses lead to the
development of a new security model and related definitions that combine and
extend the Canetti-Krawzcyk pre- and post- specified peer models in terms of
provided security assurances.
The thesis also provides a complete analysis of a one-pass key establishment
scheme. There are security goals that no one-pass key establishment scheme can
achieve, and hence the two-pass security models and definitions need to be
adapted for one-pass protocols. The analysis provided here includes
the description of the required modification to the underlying security model.
Finally, a complete security argument meeting these altered conditions is
presented as evidence supporting the security of the one-pass scheme.
Lastly, validation and reusing short lived key pairs are related to
efficiency, which is a major objective in practice. The thesis considers the
formal implication of omitting validation steps and reusing short lived key
pairs. The conclusions reached support the generally accepted cryptographic
conventions that incoming messages should not be blindly trusted and extra
care should be taken when key pairs are reused