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Advisories
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Response to New Cryptanalytic Results on Hash Functions
Three papers published at the Crypto 2004 conference
at in Santa Barbara, California announced new attacks against cryptographic
hash functions, which are typically used in creating electronic signatures
and in operating systems to store passwords. The discussed algorithms
include MD4, MD5, RIPEMD, HAVAL-128 and SHA-0. While the results detailed
in the reports could provide ammunition for hackers in their attempts
to compromise these algorithms, they fall short of providing an attacker
with the means to forge a digital signature or digital certificate,
or to compromise the confidentiality and integrity of messages sent
in conjunction with SSL (for e-commerce or browser to server communications),
S/MIME (secure e-mail), or IPSEC (secure VPNs).
As with any security mechanism, inevitable advances in cryptology are
expected. VeriSign routinely plans for the retirement of cryptographic
algorithms nearing the end of their working life and also has in place
contingency plans for the accelerated retirement of algorithms, should
they become compromised. The results published at Crypto 2004 do not
require VeriSign to take the step of accelerated retirement.
Although the results published at the Crypto 2004 fall well short of
breaking SHA-1, VeriSign is studying these results closely to determine
whether existing plans for an orderly transition to new algorithms,
as recommended by NIST in August 2002, should be expedited.
VeriSign will continue to monitor the situation, providing updates as
warranted.
At this time, however, VeriSign feels there is no need for immediate
action needed on the part of end users of VeriSign Digital Certificates
or VeriSign Digital Certificate customers. The algorithms discussed
are so-called hashing functions. While the purported weaknesses in the
algorithms are still largely theoretical, even if these algorithms were
compromised, it would have little practical effect on the confidentiality
and integrity of your PKI based systems or the information protected
by those systems. In all significant cases, the hashing functions are
either used to condense non-sensitive information (e.g. the already
public information in a certificate) or, when used in conjunction with
sensitive information, are further enhanced through the use of additional
encrypting and signing algorithms (e.g. RSA, 3 DES) whose strength is
not currently in question.
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