On Sun, 15 Mar 2015 16:32, st...@mailbox.org said: > Now, I'll look for information on how RNG in GnuPG exactly works. It *seems* > that haveged should impact on the gathering of entropy (available) at the > moment > of keypair generation on any GNU/Linux PC/laptop equipped with it (specific
You can find this in the Libgcrypt manual: Libgcrypt provides 3 levels or random quality: The level 'GCRY_VERY_STRONG_RANDOM' usually used for key generation, the level 'GCRY_STRONG_RANDOM' for all other strong random requirements and the function 'gcry_create_nonce' which is used for weaker usages like nonces. There is also a level 'GCRY_WEAK_RANDOM' which in general maps to 'GCRY_STRONG_RANDOM' except when used with the function 'gcry_mpi_randomize', where it randomizes an multi-precision-integer using the 'gcry_create_nonce' function. There are two distinct random generators available: * The Continuously Seeded Pseudo Random Number Generator (CSPRNG), which is based on the classic GnuPG derived big pool implementation. Implemented in 'random/random-csprng.c' and used by default. * A FIPS approved ANSI X9.31 PRNG using AES with a 128 bit key. Implemented in 'random/random-fips.c' and used if Libgcrypt is in FIPS mode. Both generators make use of so-called entropy gathering modules: rndlinux Uses the operating system provided '/dev/random' and '/dev/urandom' devices. rndunix Runs several operating system commands to collect entropy from sources like virtual machine and process statistics. It is a kind of poor-man's '/dev/random' implementation. It is not available in FIPS mode. rndegd Uses the operating system provided Entropy Gathering Daemon (EGD). The EGD basically uses the same algorithms as rndunix does. However as a system daemon it keeps on running and thus can serve several processes requiring entropy input and does not waste collected entropy if the application does not need all the collected entropy. It is not available in FIPS mode. rndw32 Targeted for the Microsoft Windows OS. It uses certain properties of that system and is the only gathering module available for that OS. rndhw Extra module to collect additional entropy by utilizing a hardware random number generator. As of now the only supported hardware RNG is the Padlock engine of VIA (Centaur) CPUs. It is not available in FIPS mode. 16.6.1 Description of the CSPRNG -------------------------------- This random number generator is loosely modelled after the one described in Peter Gutmann's paper: "Software Generation of Practically Strong Random Numbers".(1) 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. The implementation of the nonce generator (for 'gcry_create_nonce') is a straightforward repeated hash design: A 28 byte buffer is initially seeded with the PID and the time in seconds in the first 20 bytes and with 8 bytes of random taken from the 'GCRY_STRONG_RANDOM' generator. Random numbers are then created by hashing all the 28 bytes with SHA-1 and saving that again in the first 20 bytes. The hash is also returned as result. ---------- Footnotes ---------- (1) Also described in chapter 6 of his book "Cryptographic Security Architecture", New York, 2004, ISBN 0-387-95387-6. Shalom-Salam, 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