On Sun, 31 Mar 2013 11:45, philip.g.pot...@gmail.com said: > Can anyone shed any light on this? Why does GPG use more entropy than > /dev/random says it should?
Which /dev/random - there are hundreds of variants of that device all with other glitches. Thus GnuPG has always used /dev/random only as a source of entropy to seed its own RNG: This random number generator is loosely modelled after the one described in Peter Gutmann's paper: "Software Generation of Practically Strong Random Numbers".@footnote{Also described in chapter 6 of his book "Cryptographic Security Architecture", New York, 2004, ISBN 0-387-95387-6.} A pool of 600 bytes is used and mixed using the core RIPE-MD160 hash transform function. Several extra features are used to make the robust against a wide variety of attacks and to protect against failures of subsystems. The state of the generator may be saved to a file and initially seed form a file. Depending on how Libgcrypt was build the generator is able to select the best working entropy gathering module. It makes use of the slow and fast collection methods and requires the pool to initially seeded form the slow gatherer or a seed file. An entropy estimation is used to mix in enough data from the gather modules before returning the actual random output. Process fork detection and protection is implemented. GPG uses ~/.gnupg/random_seed but it needs to creater it first. For generating keys it also makes sure to put in a lot of new entropy just to be safe. Better be safe than sorry (cf. the recent NetBSD problem). Salam-Shalom, Werner -- Die Gedanken sind frei. Ausnahmen regelt ein Bundesgesetz. _______________________________________________ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users