![image.png](https://cdn.steemitimages.com/DQmUnZ1NVm3R1H9n4dRdR2GAL5hhKM3XfD93efzPz7ZZ7KP/image.png)

Homework for @pelon53

Explain what the collision resistance means? And what does preimage resistance mean?

Collision Resistance

means that it is incredibly difficult for two pieces of data to produce the same hash, different data will practically always produce different hashes. Now as we are talking about, let's say, SHA256 we do have to take into account that we are talking about reducing a large number of data to 256 bits of output, this means, as incredible as it sounds that it is possible, even though highly unlikely, that two different sets of data will produce the same hash, collision resistance just implies that the same hash for two different sets of data is almost negligible. Collision Resistance is a Crypto Hash Property.

Preimage Resistance

is a component of the hash function that is incredibly difficult to invert. What I think this means is that say, a hacker trying to find a password by using by attacking hash outputs would not find it feasible, even though not impossible to hack the password.

Use tronscan and etherscan to verify the hash of the last block and the hash of that transaction. Screenshot is required for checking.

Verifying blocks with Tronscan: ![image.png](https://cdn.steemitimages.com/DQmTNQX3p7QyxUoLkZJ97KdgWHY6K7ZeZtqgdnAX9vxDY3B/image.png) First we must go to tronscan.org and then scroll down to blocks (bloques in my case as Tronscan shows up in Spanish for me). And now we click on the block number which will take us to all the information we need about this block. ![image.png](https://cdn.steemitimages.com/DQmP1en864k4YmcYLH8tsty1AMCRWjT19c633Le7pvjh2bX/image.png) The hash number for this particlar block is:0000000001e4d6c0507bedf9f4ae2a7d6a36d2fac6f6e8b17d1e1c6d7bd90ddc Here are some of the transaction details: ![image.png](https://cdn.steemitimages.com/DQmV2jLv8EPANEM5o71xpa7L8rvn8ZvJ4FQGKmKZ1raCShZ/image.png) And this is the last transaction on this block: ![image.png](https://cdn.steemitimages.com/DQmXt2tBioNyNsDw7x8m7tXTLG4HjfC7emeWJ7skoyA3z3o/image.png) Last transaction hash #: f478f521ade83cb3943f6f4ef3f4d93e4a164cbda3aae223484c6132eff2fc15 Verifying blocks with Etherscan: We of course go to Etherscan.io where we find the following: ![image.png](https://cdn.steemitimages.com/DQmbS9T1J5jv9jrHuB5VaqDRmRbSWAYUy9zW23W9qPJj6TV/image.png) Here we can see the last Block mined. ![image.png](https://cdn.steemitimages.com/DQmXpjtJHsfq6AzGBVNLyHBfbS8tJJDJE1mVuK4f8Tsqs1n/image.png) And here we see the hash number 0x8d4c80da9a897c8f7ce7fb7c3e20e214ca6312509e6f7580f217886589548ee8 Then we click on transaction and go to the last one and click on it: ![image.png](https://cdn.steemitimages.com/DQmSBnwoNMj45TgQ1gkZrKCxortfu6KoNGqY5MpadTkZK7t/image.png) Here we see all transaction details including it has number: ![image.png](https://cdn.steemitimages.com/DQmPNk82Bv14oLR3dZKWwdvgLwrquBj3SjLcNfamKrbDuJ5/image.png)

Generate the hash using SHA-256 , from the word CryptoAcademy and from cryptoacademy. Screenshot required. Do you see any difference between the two words? Explain.

To do this we must go to https://passwordsgenerator.net/sha256-hash-generator/ and proceed with each phrase we are going to generate a hash for: ![image.png](https://cdn.steemitimages.com/DQmdcnLzcTm8bqbkuhp1y7n8Hi6UojJnt97K655aKGYEpba/image.png) Hash for CryptoAcademy is D03CA34B258E6E0FD06B2070DDE61B50BD4EEF6161A8EDAA4A420C9AE1BEB7F9 ![image.png](https://cdn.steemitimages.com/DQmRYG8H6UWVCk2WQex3a1RUYk9pmzkHGMBpKTjvp25cW8y/image.png) For cryptoacademy the hash is 0592F5DD27DC72E675B2AB9C77487A69FAAF84196597FA052EC099C18EE7C4C5. As we can see the hashes are completely different, and the only difference in the words themselves is that in one two letters are capitalized while the other one uses no capital letters. This is enough of a difference to produce two completely different hashes.

In your own words explain the difference between hash and cryptography.

To me a hash is a mathematical function that minimizes a large number of data into a unique string of alphanumerical characters which are incredibly difficult, close to impossible to obtain the same outcome from different sets of data. As for cryptography is to me the securing of data by encrypting the data itself making it nearly impossible for this data to be hacked. Conclusions: Hashes and cryptography are functions that enable data, in this case, on a blockchain to not be tampered with. It is this security which makes the blockchain the future of most of the functions humankind relies on. Tagging: @pelon53