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IPsec In computing, Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts packets of data to provide secure encrypted communication between two computers over an Internet Protocol network. It is used in ...
comes under the
Oakley protocol The Oakley Key Determination Protocol is a key-agreement protocol that allows authenticated parties to exchange keying material across an insecure connection using the Diffie–Hellman key exchange algorithm. The protocol was proposed by Hilarie K. ...
, which is a protocol of key management. The cookie exchange requires that each side send a
pseudorandom A pseudorandom sequence of numbers is one that appears to be statistically random, despite having been produced by a completely deterministic and repeatable process. Background The generation of random numbers has many uses, such as for random ...
number, the cookie, in the initial message, which the other side acknowledges. This acknowledgement must be repeated in the first message of the
Diffie–Hellman key exchange Diffie–Hellman key exchangeSynonyms of Diffie–Hellman key exchange include: * Diffie–Hellman–Merkle key exchange * Diffie–Hellman key agreement * Diffie–Hellman key establishment * Diffie–Hellman key negotiation * Exponential key exc ...
. If the source address was forged, the opponent gets no answer. Thus, an opponent can only force a user to generate acknowledgements and not to perform the Diffie–Hellman calculation. Note that "cookies" in the sense of IPsec are unrelated to
HTTP cookie HTTP cookies (also called web cookies, Internet cookies, browser cookies, or simply cookies) are small blocks of data created by a web server while a user is browsing a website and placed on the user's computer or other device by the user's ...
s used by web browsers. The recommended method for creating the cookie is to perform a fast
hash Hash, hashes, hash mark, or hashing may refer to: Substances * Hash (food), a coarse mixture of ingredients * Hash, a nickname for hashish, a cannabis product Hash mark *Hash mark (sports), a marking on hockey rinks and gridiron football field ...
(e.g. MD5) over the IP source and destination addresses, the UDP source and destination ports, and a locally generated secret value.


References

{{Reflist Internet protocols