random(7) Miscellaneous Information Manual random(7) random - (CSPRNG). . CSPRNG : o /dev/urandom /dev/random random(4). . o getrandom(2) 3.17. /dev/urandom ( urandom ) /dev/random ( random ). urandom random GRND_RANDOM . ( getentropy(3) getrandom(2).) . . ( ) /dev/random getrandom(2) GRND_RANDOM. /dev/urandom getrandom(2) GRND_RANDOM. urandom . GRND_RANDOM /dev/random . GRND_RANDOM /dev/random . / . . . getrandom /dev/urandom /dev/random . GRND_NONBLOCK getrandom(2). . +----------------------+--------------------+--------------------------------+--------------------------+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +----------------------+--------------------+--------------------------------+--------------------------+ |/dev/random | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +----------------------+--------------------+--------------------------------+--------------------------+ |/dev/urandom | | | | | | CSPRNG | | | | | | | CSPRNG | | | | | ( | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ) | +----------------------+--------------------+--------------------------------+--------------------------+ |getrandom() | | | | | | /dev/urandom | | | | | | | | | | | | | | | | | | +----------------------+--------------------+--------------------------------+--------------------------+ |getrandom() | | | | |GRND_RANDOM | /dev/random | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +----------------------+--------------------+--------------------------------+--------------------------+ |getrandom() | | | EAGAIN | |GRND_NONBLOCK | /dev/urandom | | | | | | | | | | | | | | | | | | +----------------------+--------------------+--------------------------------+--------------------------+ |getrandom() | | EAGAIN | EAGAIN | |GRND_RANDOM + | /dev/random | | | |GRND_NONBLOCK | | | | | | | | | +----------------------+--------------------+--------------------------------+--------------------------+ . RSA Diffie-Hellman 3072 128 ( 2^128 ) 128 (16 ) /dev/random. CSPRNG 256 256 (32 ) ( ) . getrandom(2), getauxval(3), getentropy(3), random(4), urandom(4), signal(7) 3 . . : . 6.18 8 2026 random(7)