Public-key Cryptography: Theory and Practice

3.3. Multiple-precision Integer Arithmetic

Cryptographic protocols based on the rings and demand n and p to be sufficiently large (of bit length ≥ 512) in order to achieve the desired level of security. However, standard compilers do not support data types to hold with full precision the integers of this size. For example, C compilers support integers of size ≤ 64 bits. So one must employ custom-designed data types for representing and working with such big integers. Many libraries are already available that can handle integers of arbitrary length. ...