Using four-prime RSA in which some of the bitsare specified
Scott A. Vanstone, Robert J. Zuccherato · Electronics Letters · 1994
In the Letter the authors apply their method of predetermining a certain number of bits of the RSA public key modulus to RSA using four primes. The method works just as well using four primes as it does with two, and does not appear to decrease the security level. It appears that at most 252 bit can be predetermined, whereas in the two-prime case half of the bits could be specified.