AUM is an extremely fast, small-state, cryptographically secure pseudo-random number generator and stream cipher. AUM exhibits uniform distribution, mixes rapidly, has no detected bias, and comes in three variants: AUM16, with an internal state array of 16+4 32-bit words; AUM32, with an internal state of 32+4 words; and AUM64 with a 64+4-word state. The former permit seeding with a key of up to 512 or 1024 bits, the latter with a 2048-bit key.