/* * BigInt Random Generation * (C) 1999-2007 Jack Lloyd * * Distributed under the terms of the Botan license */ #include #include namespace Botan { /* * Construct a BigInt of a specific form */ BigInt::BigInt(NumberType type, u32bit bits) { set_sign(Positive); if(type == Power2) set_bit(bits); else throw Invalid_Argument("BigInt(NumberType): Unknown type"); } /* * Randomize this number */ void BigInt::randomize(RandomNumberGenerator& rng, u32bit bitsize) { set_sign(Positive); if(bitsize == 0) clear(); else { SecureVector array((bitsize + 7) / 8); rng.randomize(array, array.size()); if(bitsize % 8) array[0] &= 0xFF >> (8 - (bitsize % 8)); array[0] |= 0x80 >> ((bitsize % 8) ? (8 - bitsize % 8) : 0); binary_decode(array, array.size()); } } /* * Generate a random integer within given range */ BigInt BigInt::random_integer(RandomNumberGenerator& rng, const BigInt& min, const BigInt& max) { BigInt range = max - min; if(range <= 0) throw Invalid_Argument("random_integer: invalid min/max values"); return (min + (BigInt(rng, range.bits() + 2) % range)); } }