I'm calculating a SHA2 hash of a certain sensitive key value. I need to store files on disk using this hash a directory path prefix. So lets say I hash the key value 150023, I get a 32-byte value which in hex is 64-characters long - quite a long filename.
What's the shortest string I can get of this 32-byte hash, that would have some degree of uniqueness? I could use Base64 but that would be about 40 chars. Should I simply truncate the 32-byte hash value? Would it have frequent collisions if I used similar key values?