[8-< snip] If I needed to use a PRNG for AES key (128 bits) and i called rand() 4 times, I still have a entropy of only 32 bits instead of 128 bits. [8-< snip] Hi Sailesh, I dont use RNG's for cryptographic applications, i have used them for biomolecular simulations. Use of RNG's in cryptography is a very well established mathematics so i dont think you will have problems getting ur answer.Sorry cant answer ur question :(. But i kno of some people who may help u out. give me some time ok! Chao Sankha