RFC 2785 on Methods for Avoiding "Small-Subgroup" Attacks

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        RFC 2785

        Title:	    Methods for Avoiding the "Small-Subgroup" Attacks
                    on the Diffie-Hellman Key Agreement Method for
                    S/MIME 
        Author(s):  R. Zuccherato
        Status:     Informational
	Date:       March 2000
        Mailbox:    robert.zuccherato@xxxxxxxxxxx
        Pages:      11
        Characters: 24415
	Updates/Obsoletes/SeeAlso: None
        I-D Tag:    draft-ietf-smime-small-subgroup-03.txt

        URL:        ftp://ftp.isi.edu/in-notes/rfc2785.txt


In some circumstances the use of the Diffie-Hellman key agreement
scheme in a prime order subgroup of a large prime p is vulnerable to
certain attacks known as "small-subgroup" attacks.  Methods exist,
however, to prevent these attacks.  This document will describe the
situations relevant to implementations of S/MIME version 3 in which
protection is necessary and the methods that can be used to prevent
these attacks. 

This document is a product of the S/MIME Mail Security Working Group
of the IETF.

This memo provides information for the Internet community.  It does
not specify an Internet standard of any kind.  Distribution of this
memo is unlimited.

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Joyce K. Reynolds and Sandy Ginoza
USC/Information Sciences Institute

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<ftp://ftp.isi.edu/in-notes/rfc2785.txt>