Going from 22 base-64 characters to 22 base-36 characters still only drops you to about 113 bits of entropy. Unless we're talking significantly more than a qua

Going from 22 base-64 characters to 22 base-36 characters still only drops you to about 113 bits of entropy. Unless we're talking significantly more than a quadrillion images in the system, getting a collision on a 113-bit random ID is exceedingly unlikely. I strongly suspect there were more problems in the system than just toLower(), or else the system was hosting significantly more than a quadrillion images. Your mention of "or just incrementing" sounds much closer to the mark.