[botan-devel] Security Notification: Botan 1.10.8 + 1.11.9 released

Uri Blumenthal uri at MIT.EDU
Fri Apr 11 00:35:59 EDT 2014


Both packages built with clang-3.4 on Mac OS X v10.9.2.

Botan-1.10.8 built with 
python configure.py --with-boost --with-zlib --with-bzip2 --with-gnump --with-openssl --with-boost-python --with-python-version=2.6 --prefix=/opt/local --enable-modules=cvc,cms --cc=clang --enable-sse2 --enable-ssse3 --enable-aes-ni --with-tr1=boost
"./check —test” fails. See the attached check-1.10.8.out.

Botan-1.11.9 built with
python configure.py --with-boost --with-sqlite3 --with-zlib --with-bzip2 --with-lzma --with-gnump --with-openssl --with-boost-python --with-python-version=2.6 --prefix=/opt/local --enable-modules=cvc --cc=clang --enable-sse2 --enable-ssse3 --enable-aes-ni 
./botan cpuid
CPUID flags: sse2 ssse3 sse41 sse42 avx2 rdtsc bmi2 clmul aes_ni rdrand
“./botan-test" fails. See the attached botan-1.11.9.out.

It would be nice if these problems could be explained and a fix suggested.

Thanks!


On Apr 10, 2014, at 20:10 , Jack Lloyd <lloyd at randombit.net> wrote:
> I've released new versions of Botan (1.10.8 and 1.11.9) fixing a serious bug in
> prime testing. A change in version 1.8.3 resulted in Miller-Rabin primality
> tests being done with a single random base rather than a sequence of such
> bases. Miller-Rabin is a probabilistic algorithm where the rate of failure
> (classifying a non-prime as prime) decreases as iterations increase, so having
> a single test is more or less the worst case scenario.
> 
> What are the actual effects of this bug? There are two major cases: generating
> a new RSA key (or DSA or DH parameters), and testing an untrusted DH group
> provided by a third party (for instance during TLS DHE key exchange, where the
> server hands the client an arbitrary DH group). RSA generation should be safe;
> a proof (in http://www.math.dartmouth.edu/~carlp/PDF/paper88.pdf) shows that
> for *randomly* chosen n the probability of a false accept is quite low and and
> decreases rapidly as the size of the number increases, for instance with
> randomly chosen 600 bit numbers even a single test should fail no more often
> than 2^-75. In addition newly generated RSA keys are automatically checked for
> consistency (including checking the primes, meaning a second Miller-Rabin
> test), so in the event that a key was created with a non-prime factor, the self
> test would with high probability fail and the constructor would throw an
> exception.
> 
> The case of DH parameter verification is rather bleaker, as obviously the value
> is chosen by the attacker, so about the best we can hope for is the base 3-in-4
> detection rate of Miller-Rabin: that is, 75% of the time we would detect this
> invalid prime, and 25% of the time we would not, and accept a composite as
> prime.
> 
> I would like to thank Jeff Marrison for finding and reporting this issue.
> 
> The only other change in 1.10.8 is a modification for HMAC, which now accepts
> keys as large as 512 bytes. This is primarily so PBKDF2 can accept very long
> passphrases.
> 
> 1.11.9 has some changes to PKIX path validation; when validating we return a
> set of all the errors with the most severe error being provided as the primary
> result. This prevents a seemingly innocuous error (such as an expired
> certificate) from hiding an obviously serious error (such as an invalid
> signature). A bug that prevented OCSP from working with some common responders
> was also fixed. And implementations of HMAC_DRBG and the RFC 6979 deterministic
> nonce generator were added.
> 
> As always download links are at http://botan.randombit.net/download.html
> 
> My apologies on the mess. From the events of this week it appears I'm at least
> in good company.
> 
> Jack
> _______________________________________________
> botan-devel mailing list
> botan-devel at randombit.net
> http://lists.randombit.net/mailman/listinfo/botan-devel

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