Entropy sec con_01022018v2-public
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Entropy description and importance to cryptography.
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Entropy sec con_01022018v2-public
- 1. Cisco Confidential 2017 All Rights Reserved Entropy Debra Baker, CISSP CCSP
- 2. Cisco Confidential 2017 All Rights Reserved Cryptographic Best Practices
- 3. No matter how good the algorithm, bad random numbers =
- 4. Cisco Confidential 2017 All Rights Reserved What is entropy? • Entropy is true randomness • Such as atmospheric pressure • and Lava Lamps (cloudflare’s lava lamp wall…) • Used to seed the DRBG
- 5. • Cryptographic key generation (MACSec, IPSec, SSH, TLS ...) • Nonces and initialization vectors (802.11i, EAP, MACSec...) • Padding schemes, digital signatures (DSA, OTPs... ) • Using poor random numbers (random != unique) can have catastrophic consequences. And cause severe embarrassment! Random numbers and security
- 6. Entropy Overview Noise Source Digitization Conditioner (Optional) ENTROPY SOURCE Health Tests Entropy output to DRBG
- 7. /dev/[u]random - Linux Image courtesy of: http://samvartaka.github.io; updated by Debra Baker Conditioning is Optional per latest Draft NIST SP 800-90C Output to DRBG Seed File Conditioned SHA-1/ SHA-256/ (preferred) SHA-512 OpenSSL
- 8. Cisco Confidential 2017 All Rights Reserved Typical Entropy Sources System Time Entropy Pools Random Bits Clock Cycles /proc PIDS /dev Names interrupts Drivers Info Disk Request Keyboard /Mouse
- 9. Cisco Confidential 2017 All Rights Reserved Entropy Accumulator Output Function 32 Separate Entropy Pools ( Health Tests Random Bits Conditioner Output to DRBG seed file Entropy Sources Reseed Generator KEY (Internal State) Seed File 32 Separate Entropy Pools (32 Separate Entropy Pools (32 Separate Entropy Pools ( 32 Separate Entropy Pools (P0, P1,...P31) Fortuna Entropy Source – FreeBSD 11.1 and above QNX 7.0 Fortuna ensures blocked unless have enough and random data to seed DRBG
- 10. Cisco Confidential 2017 All Rights Reserved /dev/[u]random and Embedded Systems Image courtesy of: http://samvartaka.github.io
- 11. What to do? • Software-Only… o QNX 7.0 (random.c) – Fortuna o FreeBSD 11.1 – Fortuna o Truerand.c • Use a Hardware RNG o Act2Lite, Cavium, on-board entropy chip intel (DRNG) • Make sure your entropy pool is seeded on boot and reseeded properly • Test the PRNG using NIST SP800-90B assessment tools
Editor's Notes
- 7 Most Dangerous New Attacks – 2017 https://www.sans.org/the-seven-most-dangerous-new-attack-techniques Weak Random Number Generators Creating good random numbers is a challenging problem. Small devices make it difficult to collect enough random events to initialize the algorithms used to create random numbers. Recent research has shown how this can be exploited to break WPA2 encryption. But the problem reaches well beyond Wi-Fi and WPA2. Encryption without good random numbers will put a wide range of security related algorithms at risk. Why it matters: Most wireless protocols, not just Wi-Fi, rely on good random numbers to encrypt connections. Without good random numbers, these connections are not secure.
- Deterministic Random Bit Generator Lava Lamp gif is from the Smithsonian web site: https://www.smithsonianmag.com/arts-culture/the-history-of-the-lava-lamp-21201966/ All cryptographic algorithms are seeded with a random number from a random source.
- From 33C3: Analyzing Embedded Operating System Random Number Generators paper http://samvartaka.github.io/cryptanalysis/2017/01/03/33c3-embedded-rngs https://github.com/freebsd/freebsd/blob/master/sys/dev/random/fortuna.c
- From 33C3: Analyzing Embedded Operating System Random Number Generators paper NIST SP 800-90C (optional for conditioning of random symbol data)
- From 33C3: Analyzing Embedded Operating System Random Number Generators paper http://samvartaka.github.io/cryptanalysis/2017/01/03/33c3-embedded-rngs https://github.com/freebsd/freebsd/blob/master/sys/dev/random/fortuna.c
- From 33C3: Analyzing Embedded Operating System Random Number Generators paper http://samvartaka.github.io/cryptanalysis/2017/01/03/33c3-embedded-rngs https://github.com/freebsd/freebsd/blob/master/sys/dev/random/fortuna.c