Rng class

class crsyspqc.Rng

Random Number Generator to NIST SP800-90A.

SEED_BYTES = 128

Size in bytes of seed file.

class Strength

Required security strength for user-prompted entropy.

BITS_112 = 0

112 bits of security

BITS_128 = 1

128 bits of security (default)

BITS_192 = 2

192 bits of security

BITS_256 = 3

256 bits of security

class Opts

RNG options.

DEFAULT = 0

Default option

NO_INTEL_DRNG = 524288

Turn off support for Intel(R) DRNG for the current session.

static bytestring(n)

Generate an array of n random bytes.

Parameters:

n (int) – Required number of random bytes.

Returns:

Array of random bytes.

Return type:

bytes

static initialize(seedfilename)

Initialize the RNG generator using a seed file.

Use this function if Intel(R) DRNG is not available on your system (check using Rng.initialize_ex()). Call at the start of a session to load entropy stored in the seed file, and use again at the end of a session to save any accumulated entropy. If the seed file does not exist, it will be created using any available entropy. The seed file is automatically updated by this procedure. Use Rng.make_seedfile() to create the first time.

Parameters:

seedfilename (str) – Full path name of seed file.

Returns:

Zero if successful.

Return type:

int

static initialize_ex(opts=0)

Query and initialize the RNG generator using Intel(R) DRNG, if available.

Parameters:

opts (Rng.Opts) – Specify Rng.Opts.NO_INTEL_DRNG to explicitly turn off support.

Returns:

Support status for Intel(R) DRNG. If available, then returns a positive value 1 or greater; else a negative error code.

Return type:

int

static make_seedfile(seedfilename, strength=1, prompt='')

Create a new seed file suitable for use with Rng.initialize().

This uses a dialog window and expects the user to type in random keystrokes. Such a GUI interface may not be appropriate in all circumstances.

Parameters:

• seedfilename (str) – Full path name of seed file to be created. Any existing file of the same name will be overwritten without warning.

• strength (Rng.Strength) – Required security strength (default=128 bits).

• prompt (str) – Optional prompt for dialog.

Returns:

Zero if successful.

Return type:

int