It is widely believed that public/private keys or certificates are “more secure” than passwords. E.g., an SSH login via key rather than using a password. Or a site-to-site VPN with certificate authentication rather than a pre-shared key (PSK). However, even certificates and private keys are not unlimited secure. They can be compromised, too, since the public-key cryptography only implies that private keys won’t be exposed if a brute-force attack is nearly impossible.
So, what’s the real security level of passwords compared to public keys/certificates?
Continue reading Passwords vs. Private Keys
Unpredictable random numbers are mandatory for cryptographic operations in many cases (ref). There are cryptographically secure pseudorandom number generators (CSPRNG) but the usage of a hardware random number generator (TRNG) is something I am especially interested in since many years. While there are many proprietary TRNGs (list) with different prices, I had a look at two cheap solutions: the Raspberry Pi’s hardware random number generator as well as an application that uses a DVB-T/RTL/SDR stick for gathering some noise.
I have tested both of them with various options and ran them against the dieharder test suite. In this post I am listing the CLI commands to get the random data from those source and I am listing the results of the tests.
Continue reading Playing with Randomness
Last but not least I was interested which “home-calling” connections my Yamaha R-N500 Network Receiver initiates. In my previous post I already analyzed the open ports within the network, while I showed a complete Apple AirPlay capture here. This time I was only interested in outgoing TCP/UDP connections to the Internet as well as how the Yamaha App “NP Controller” communicates with the receiver.
It turned out that it was not easy for me to fully analyze such a packet trace even though only a couple of connections were made. It consists of many protocols that I am not familiar with such as UPnP, MDNS, SSDP, and RTP. Anyway, ere we go:
Continue reading Yamaha R-N500 Network Receiver Packet Capture
This is a mathematical post which is related to the xkcd 936 comic about password strength. The central question is: What is better for passwords? A password containing a few random characters or a passphrase containing a (less) few random words? Here comes a mathematical discussion.
Continue reading Password Strength/Entropy: Characters vs. Words