Greetings to all steemians and welcome to the second week of the steemit crypto academy's season 3

Introduction.

I am very excited to be a part of this class because I have learnt something new.

This week's lecture is on Hash and Cryptography where we have being tasked to answer questions on resistance of collision and preimage, verify transactions on etherscan and tronscan, among others.

I would now like to present my answers to the questions asked.

Explain What Does The Resistance To Collision And What Does Resistance To Preimage Mean ?

Before I begin, I would like to talk about hash and cryptography.

What Is Hash, It's Characteristics And Functions ?

Hash can be described as a mathematical function that can convert information or raw data into a hash ( summarized information ) . It doesn't matter if the information in the block to be converted is large or small because the converted information would be a summary of the block's information.

Hashes are unique and secure cryptographic functions that helps us to generate a 64 character alphanumeric code which are in nature from the data or information to be converted. They also allow us to track transaction details on blockchains.

Characteristics of a hash.

• A hash is a 64 alphanumeric code.

• A hash is unique and case sensitive.

• A hash is of fixed length, irreversible and not repeatable.

• A hash is efficient in it's execution and doesn't require too much computational power.

• A hash is very safe and secure.

Functions of a hash.

• A hash is used for cryptocurrency mining.

• A hash is used to track transaction details.

• A hash is used to create wallet addresses.

• A hash is used in smart contracts to make them more versatile.

Cryptography.

Cryptography is a way or method of securing information by use of codes which prevent third parties from being able to access the intended hidden information.

In cryptography, it is clear that a message has been hidden but it cannot be read because it has been encrypted and can only be decrypted by sender or receiver of the message.

Blockchains use this as a means of securing their network and preventing people from stealing the assets of other users.

There are 3 classes of cryptography;

Symmetric cryptography is the oldest among the 3 which is also known as private key. In this case, there is just one key known by both the receiver and sender which can be used to decrypt the message.

Asymmetric cryptography is the private and public keys system. In this, the private and public keys are different where the public key as the name implies is public and can be sent to all without having impact on the private key.

Hybrid cryptography utilizes and seeks to reduce the limitations of both symmetric and asymmetric cryptography by providing fast and secure ways of decrypting messages.

What Is Resistance To Collision ?

Resistance to collision is a property of the hash functions where there are two different inputs which do not provide the same output data.

This system of having 2 different inputs not providing the same data increases security of the function by making it very very difficult to hack the data.

The term collision means that two different data give the same output data.

In this regard, resistance to collision is therefore preventing two different inputs from giving the same output.

The resistance to collision is in SHA-256 which is one of the best new hash functions. Because of how good and secure the SHA-256 hash is, there is almost zero collision because the 2 different data cannot give the same output.

Resistance to collision performs a very vital role because it ensures that every hash is unique with different output data and making those output data difficult to access by third parties.

Resistance To Preimage.

Resistance to preimage is also a property or characteristic of the hash function that makes it difficult for third parties to access output data that corresponds to the input data.

This system therefore gives extra security to the hash by even making it more difficult to access or hack.

There are two types of resistance to preimage;

Preimage resistance which prevents hackers from accessing hash data and

Second preimage which prevents the finding of the second input of data with the same output.

Use Tronscan And Etherscan To Verify The Hash Of The Last Block And The Hash Of That Transaction.

Using Etherscan.

To verify the hash of the last block and and it's transaction on ethersan, these steps are followed;

Step 1: Search Etherscan on google.

Step 2: Click on Etherscan to launch the homepage of Etherscan.

Step 3: On the homepage, there is latest blocks and latest transactions.

To view the details of the last block, click on the first block in the latest blocks category to display the block details.

To verify the transactions of the block,

Step 1: Click on transactions to view the various transactions.

Step 2: Click on first transaction to view its details.

Step 3: Check details and check to see if status reads "success**. Click on block number to view block details.

Step 4: View block height and transaction hash. View status to read "success".

Step 5: Copy and paste transaction hash of the block to verify its transaction. If both transactions are same and reads success, then the transaction is verified.

Transaction hash: 0x8a77c3746018def3b378b913038bf59d79247137db187c6d815d5bb018f3d0b5

Using the tronscan.

To verify the hash of the block and it's transaction on tronscan, these steps are used.

Step 1: Search for tronscan.

Step 2: Click on tronscan to launch.

Step 3: On the homepage, you can see blocks and transactions.

Step 4: Click on first block to view the block details.

To verify the transaction details,

Step 1: Click on transaction of choice. I am viewing the transaction details of the first transaction.

Step 2: Take note of the transaction details and make sure the status reads "confirmed".

Step 3: Copy and paste the the transaction hash code and search in the search bar to verify transaction. Make sure status reads "confirmed".

Step 4: Copy and paste the block number to verify its details.
The block details is verified as shown.

Generate The Hash Using SHA-256 from the word CryptoAcademy and from cryptoacademy And Explain The Differences.

Step 1 : Click on the link provided or search for SHA-256 in google. I clicked on the link SHA-256

Step 2: Type your text into the search box and click on generate.

In this case, CryptoAcademy.

Step 3: It's hash code can be found below the search box as shown.

D03CA34B258E6E0FD06B2070DDE61B50BD4EEF6161A8EDAA4A420C9AE1BEB7F9

Step 4: Search for cryptoacademy and click on generate.

Step 5: The hash code is found below the search box as indicated.

0592F5DD27DC72E675B2AB9C77487A69FAAF84196597FA052EC099C18EE7C4C5

Differences between the 2 generated hashes.

After typing the two words given and hash generated, I observed that, although the words are very similar, the hashes generated are very different from each other.

The first input starts with an alphabet D and the second starts with a number 0.

These different generated hashes shows an example of the resistance to collision already discussed above where 2 inputs cannot display the same output.

The Difference Between Hash And Cryptography.

Hash.

• A hash is a method of obtaining secret code for input data in alphanumeric codes.

• The calculation is easy with the help of tools like the SHA-256.

• A hash contains very secure information.

• A hash does not require the use of keys to operate.

• A hash has a specific or fixed number of characteristics.

• A hash code cannot be edited.

Cryptography.

• Cryptography is a method of encrypting data by use of certain softwares.

• Encrypted data can be accessed with keys from the sender or receiver.

• Data sent using cryptography is very secure and often need decryption since they are encrypted.

• It is not as easy to decrypt information like in hashing where it is easy using the SHA-256 calculator.

The differences between hash and cryptography are tabulated below.

Hash	Cryptography
The length of information in hashing is fixed	Length of information in cryptography is not fixed
Keys are not used for decrypting data	Keys are used to decrypt data
It is easier to decrypt data	It is more difficult to decrypt data
Data is less secure	Data is more secure
Does not need encryption and decryption of data	Involves encryption and decryption of data

Conclusion.

I must say a very big than you to prof @pelon53 for this very informative lecture.

Through the lecture and further research, I have learnt that hash is a mathematical or computer science term used to convert raw data into packaged well defined information whilst cryptography is a way of securing data by use of codes where the data needs encryption and decryption.

I also learnt how to very blocks and transactions on the tronscan and etherscan.

I was able to generate the hash of cryptoacademy and CryptoAcademy using the SHA-256.

I learnt the different characteristics and differences between hash and cryptography where cryptography is a more secure way of sending information because it is easier to decrypt hash data.

Thank you.