An RSA public key is a small exponent for encryption and a large composite pq where p and q are large primes. There's more to it, naturally, but I'll stop ther

An RSA public key is a small exponent for encryption and a large composite pq where p and q are large primes. There's more to it, naturally, but I'll stop there. You can have many many RSA keys of any given size, say 2048 bits for now. So something somewhat less than 2^2048 possible keys for 2048 bit RSA keys, let's say 2^2000 keys, which... is a lot! Since one should generate keys randomly we can expect that no one key will be much more frequently used than any other, so Huffman encoding is right out, but even if you try Huffman encoding anyways you'll find that most keys will end up with Huffman codes that are longer than the keys themselves meaning that the keys are not compressible! Thinking about AES-256 will be easier. Say we have 2^40 computers able to randomly generate 2^64 AES-256 keys every day. Well, it will still take a long time to generate all possible AES-256 keys. So say in the best case scenario we get close to 2^120 keys or so. How would we even measure their frequencies so we could assign Huffman codes to them? Well, we can't, and even if we could most keys would have a frequency between 1 and 3. And still the next key to be generated could be outside that set so we really have to assign a code to each key, and there's... 2^256 possible keys... which means that even if we could assign a code to each key we couldn't write that down because there's not enough atoms on Earth to do it with. But let's say we just define a collation of AES-256 keys and assign then Huffman codes in order... But now we'll soon see that most keys will get codes assigned that are longer than 256 bits. Which means that the average input to this compressor would... yield an expansion, not a compression.