Random numbers are critical in every cryptographic fields. They can be used as cryptographic key, seed, nonce, initialization vector, etc. In this paper, new (pseudo) random number generator (PRNG or RNG) based on computer's source is proposed. The principle of method consist in collecting (nearly) random sources produced from computer and used it as seed for (pseudo) random number generation. Random number generator produces 128, 256-bit keys for symmetric ciphers and various length prime numbers. Random numbers are used as seed or initialization vector for pseudorandom number generator and it generates arbitrary keys. Generated (pseudo) random numbers are tested by NIST Statistical test suite.