Yes, this is correct. It's a really simple principle, and I think an explanation can help you understand :) Suppose you have 3 holes, and 4 pigeons, and you s

Yes, this is correct. It's a really simple principle, and I think an explanation can help you understand :) Suppose you have 3 holes, and 4 pigeons, and you stuff the pigeons into holes. There must be 1 hole with at least 2 pigeons, right? The same is true with hash functions. If you're hashing data down to a fixed length, like say 256-bits with sha-256, and the data is longer than 256 bits, there must be a collision somewhere.