urandom
– pseudorandom number generation¶
This module implements a subset of the corresponding CPython module,
as described below. For more information, refer to the original
CPython documentation: random
.
This module is used to generate pseudorandom numbers. On all Pycopy
platforms, this module is not seeded on startup, which means that if
you do not explicitly call seed()
function with a suitable varying value,
the numbers returned by the getrandbits()
function will be the same for
each fresh interpreter session. This is a deliberate design decision, to
emphasize the fact that this module does not provide true randomness.
Seeding the pseudorandom generator lies on a user application,
by whatever means suitable for a particular application. For example,
having a pseudorandom, but stable predictable sequence (as provided by
this module by default) is useful for reproducible testing. For some
applications, seeding with the current time (perhaps, lower milliseconds
or microseconds of it, as provided by utime.ticks_ms()
or
utime.ticks_us()
) would be enough. Yet for other, a true random
generator may be required. (Note that this module does not guarantee
that it is a cryptographically secure random number generator). For
systems which support it, a highquality random number generator should
be provided by uos.urandom()
function (values from which can be used
to seed this module).
Functions¶

urandom.
seed
(value)¶ Seed pseudorandom generator with an integer value, which should be sufficiently random itself. As explained above, if this function is not called, the numbers returned from
getrandbits()
will be the same for each session.

urandom.
getrandbits
(num_bits)¶ Return an unsigned (nonnegative) pseudorandom number of num_bits bit size, i.e. in the range of [0, 2**num_bits  1] (inclusive). Miximum supported value of num_bits is 32, though some implementations may apply even lower limit (so use the value not higher than actually needed for a particular use).