I am asking a simple question. Why we say that we would always get a new hash in a blockchain? Why we can't have collisions?

One way of collision is that the hard disk becomes full and there is no more space to store a transaction.

Some body please guide me.



1 Answer 1


Blockchain uses a cryptographic hash function that is designed to have collision resistance. Thus, while it's possible you might run into a pair of inputs that produce the same output... it's very very unlikely to happen by chance; and it is believed to be very difficult to intentionally find such a pair of inputs.

Disk space has nothing to do with collisions in the hash function.

  • $\begingroup$ Hashes are linked to each other. For each block we have a hash value. Suppose we get a Hashvalue for a block but there is no disk space. Then we use a brand new harddisk to store that block. How will we link two blocks on different harddisks? $\endgroup$ Dec 31, 2019 at 13:39
  • $\begingroup$ @user2994783, that's not how Bitcoin (or other blockchains) work, and in any case, it's a separate question that should be asked separately (but probably would be best to ask on the Bitcoin Stack Exchange site). $\endgroup$
    – D.W.
    Dec 31, 2019 at 18:36

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