# Manual browser: qsafe(1)

QSIEVE(1) | General Commands Manual | QSIEVE(1) |

# NAME

**qsieve**,

**qsafe**— generate system moduli file

# SYNOPSIS

qsieve |
[megabytes bits [initial]] |

qsafe |
[trials [generator]] |

# DESCRIPTION

The**qsieve**utility will list candidates for Sophie-Germaine primes (where q = (p-1)/2) to standard output. The list is checked against small known primes (less than 2**30). This step is both processor and memory intensive.

The *megabytes* value sets a limit for the internal sieve buffer. This should be small enough to remain entirely in memory. Swap thrashing can increase the run time from hours to days or weeks! When the *megabytes* value is zero (0), **qsieve** will select a default suitable for the *bits*.

The *bits* value sets the length of the generated possible primes (typically 768, 1024, 1536, 2048, 3072, or 4096, although others can be used for variety).

The optional *initial* value (hex) specifies the beginning of the search. Otherwise, **qsieve** generates a randomly selected number.

The **qsafe** utility will perform a Miller-Rabin primality test on the list of candidates (checking both q and p) from standard input. The result is a list of so-call "safe" primes to standard output, suitable for use as Diffie-Hellman moduli. This step is merely processor intensive.

The *trials* value sets the number of Miller-Rabin interations (typically 16 to 128).

The optional *generator* value (hex) limits testing to candidates with a specific generator (usually 2). Otherwise, **qsafe** will test each candidate and suggest a generator.

# SEE ALSO

moduli(5)# HISTORY

These programs were originally developed for the Photuris project, and later the OpenSSH project.July 28, 1997 | NetBSD 7.0 |