scicrypt-bigint

This is a part of scicrypt. For more information, head to the scicrypt crate homepage.

This crate implements a BigInteger, for which most arithmetic operations take a constant amount of time given the specified sizes. This crate is nothing more than a convenient wrapper around the low-level constant-time functions from GMP.

If the crate is not working as expected, consider running with --debug to hit the debug_assert!()s, to check that the preconditions are met for some of the low-level functions.

Almost all function should run in constant-time, and only leak information about the length of the inputs. This also holds for overloaded operators (e.g. equality is constant-time). Some functions are not constant-time:

• Initializing from strings using from_string
• partial_cmp_leaky
• lcm_leaky
• mod_u_leaky
• set_bit_leaky and clear_bit_leaky
• is_probably_prime_leaky

To make code easier to read, one can call leak() on an UnsignedInteger to get a LeakyUnsignedInteger that supports overloaded operators for leaky operations.

We are unsure about random number generation. Also note that division may leak some information about the size of the resulting value.