Social:Cryptoperiod
A cryptoperiod is the time span during which a specific cryptographic key is authorized for use. NIST's guidelines[1] typically recommend a long-term cryptoperiod of 1 - 3 years for asymmetric keys [2] and ≤ 2 years for symmetric keys.[3]
Factors to consider include the strength of the underlying encryption algorithm, key length, the likelihood of compromise through a security breach and the availability of mechanisms of revoking keys.
In traditional cryptographic practice, keys were changed at regular intervals, typically at the same time each day. The code word for a key change, in NSA parlance, is HJ or Hotel Juliet in the NATO phonetic alphabet.[4][5]
NESTOR in Vietnam
During the Vietnam War, the United States issued its forces a series of secure voice encryption equipment code-named NESTOR. According to a U.S. Army history: "To maintain compatibility, key changes had to occur simultaneously in all units. The time chosen for this change was midnight, tactically the worst possible time because the greatest number of enemy contacts occurred from 2200 to 0200. Moreover, where several units shared the same keying device, having to move at night to change key settings was inconvenient and dangerous and added to the reasons for not using the equipment. Later the time of the daily NESTOR key change was moved to 0600."[6]
References
- ↑ NIST Special Publication 800-57 Part 1 Revision5, Recommendation for Key Management, Relevant information located (NIST, 2020, pp. 45-47).
- ↑ https://www.keylength.com/en/4#Biblio10
- ↑ https://www.keylength.com/en/4#Biblio10
- ↑ "Telecommunications Handbook". U.S. Department of State Foreign Affairs. December 2010. https://fam.state.gov/FAM/05FAH02/05FAH020520.html. Retrieved 2016-01-12.
- ↑ "Common Crypto Terms". http://jproc.ca/crypto/terms.html.
- ↑ Vietnam Studies—Division-Level Communications 1962-1973 , Lieutenant General Charles R. Myer, U.S. Department of the Army, 1982, Chapter 8
- ↑ (OUTDATED) - old 1-7 day Triple DES metric."CSEC: Cryptographic Algorithms". Archived from the original on 2011-06-17. https://web.archive.org/web/20110617055733/http://www.cse-cst.gc.ca/its-sti/services/crypto-services-crypto/ca-ac-eng.html. Retrieved 2011-05-02.
- Conduct Unbecoming, Randy Shilts, Macmillan, 2005, p. 117, describes HJ key change procedure
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