1,245 reputation
25
bio website callas.org/jon
location Hilbert Space
age
visits member for 2 years, 8 months
seen Sep 2 at 6:55

Cryptographer. Co-author of OpenPGP, DKIM, syslog-sign, ZRTP, the Skein hash function, Threefish cipher, and other things.

Businessman. Co-founder of PGP Corporation, Silent Circle, World Benders, and others. Presently CTO at Entrust.

Software engineer. Worked at the above as well as Apple, DEC, NASA, and others.


Sep
24
awarded  Autobiographer
Mar
6
awarded  Yearling
Nov
19
answered Has threefish successfully been attacked (practically or theoretically)?
Aug
27
awarded  Critic
Jun
19
answered How to build an electro-mechanical public key cipher machine?
Mar
6
awarded  Yearling
Dec
12
answered Are there any standards of multi-prime RSA key generation?
Dec
12
answered Can I use PGP to sign a message without providing cryptographic non-repudation?
Oct
30
answered Is an RSA variant with public exponent $e=f+(p-1)\cdot(q-1)$ safe (for $f$ random in some small interval)?
Oct
30
answered Can ElGamal encryption and ElGamal signatures be used together sharing the same key-pairs?
Oct
24
comment Could the Enigma algorithm be classified as a Feistel network?
Stream ciphers operate on characters, or arguably even bits in a stream. For Enigma, it's characters. Binary ones like Lorentz or RC4 can be thought to work on bits. Engima takes a character, rattles it around a path and it goes to another character map. (And the wheels ratchet one place.) Computer stream ciphers are a PRNG that is XORed onto the plaintext to yield ciphertext. Block ciphers take a binary block and the key giving another block. That's it. We use chaining modes to encrypt more than one block, but it works on blocks. It is a mapping of input blocks of bits to output blocks.
Oct
2
answered What's the fundamental difference between Diffie-Hellman and RSA?
Oct
2
answered Could the Enigma algorithm be classified as a Feistel network?
Oct
2
answered When is each key used when encrypting an email using OpenPGP?
Sep
25
answered Which is more secure using a CSPRNG for a One-time pad, or AES?
Aug
21
comment Are there hash algorithms with variable length output?
Actually, the SHA-3 schedule is "by the end of 2012" so it's about where one would expect.
Jul
31
answered Purpose of outer key in HMAC
Jul
31
answered Purpose of outer key in HMAC
Jul
10
answered RC4 Keylength Limits
Jun
19
comment What algorithm does PGP use to encrypt email?
I wouldn't point to pgpi.org. It's over a decade out of date and not maintained. But great answer. -- Jon