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Galois/Counter Mode (GCM). Authors:. Date: 2010-09-10. Abstract. The Galois/Counter Mode of AES is presented. GCM, what and why?. An authenticated encryption mode for AES, like CCM Uses CTR-mode for encryption and GHASH for authentication Specified by NIST in SP 800-38D
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Galois/Counter Mode (GCM) Authors: Date: 2010-09-10 Dan Harkins, Aruba Networks
Abstract The Galois/Counter Mode of AES is presented. Dan Harkins, Aruba Networks
GCM, what and why? • An authenticated encryption mode for AES, like CCM • Uses CTR-mode for encryption and GHASH for authentication • Specified by NIST in SP 800-38D • Widely used– IPsec, IKE, 802.1ae, TLS/SSL, IEEE P1619.1, SRTP. • Suitable for high speed (> 10G/s) encryption, unlike CCM • Text is encrypted and authenticated in 1 pass, not 2 • 1 AES encrypt operation and 1 GF(2^128) multiply per 128-bit block • Can be pipelined for high speed implementations • Memory consumption vs. speed trade off possible • CCM would be a bottleneck for VHT, GCM would not • The GCM with GMAC Protocol, or GCMP. • Key length is 128-bits, MIC length is 128-bits, nonce is 48-bits Dan Harkins, Aruba Networks
GCMP-protected MPDU • Looks sort of like the CCMP-protected MPDU except the MIC is 16 octets and its not encrypted the way the data is. • Please see 11-10/1032/r1 for suggested text Dan Harkins, Aruba Networks
References • NIST Special Publication, SP 800-38D, November 2007 Dan Harkins, Aruba Networks