download:	protocol specification in plain text
	page in compressed postscript
	page in pdf
	page source in latex
	bibTeX references

Lowe modified Denning-Sacco shared key

Author(s): Gavin Lowe (1997)

Summary: Modified version of the Denning-Sacco shared key protocol to correct a freshness flaw. Distribution of a shared symmetric key by a trusted server and mutual authentification. Symmetric key cryptography with server and timestamps.

Protocol specification (in common syntax)

`A, B, S` :	`principal`
`Nb` :	`nonce`
`Kas, Kbs, Kab` :	`key`
`T` :	`timestamp`
`dec` :	`nonce -> nonce`

`1`.	`A`	`->`	`S`	:	`A, B`
`2`.	`S`	`->`	`A`	:	{`B, Kab, T,` {`Kab, A, T`}`Kbs`}`Kas`
`3`.	`A`	`->`	`B`	:	{`Kab,A, T`}`Kbs`
`4`.	`B`	`->`	`A`	:	{`Nb`}`Kab`
`5`.	`A`	`->`	`B`	:	{`dec(Nb)`}`Kab`

Description of the protocol rules

This version add a nonce handshake (messages 4, 5) at the end of Denning-Sacco shared key to prevent the attack from [Low97].

Requirements

See Needham Schroeder Symmetric Key.

References

[Low97]

Citations

[Low97]: Gavin Lowe. A family of attacks upon authentication protocols. Technical Report 1997/5, Department of Mathematics and Computer Science, University of Leicester, 1997.

last modified 12/11/2002.

Home

Previous Index Next

Send a comment