# How is a block-chain stored?

Background of the problem: I am undertaking a blockchain course at University and I have taken up a case study for blockchain that relates to logistics. The requirements are simple, yet I am confused with the storage segment of blockchain. Given that we have a table of deliveries to be made, I incorporate certain fields of the table into the blockchain.

Problems Faced:

1. Would the data (payload of the block) be stored as plaintext?
2. And how would I verify that the table hasn't been tampered with and it satisfies the blockchain?
• After a discussion with my fellow mod I've removed the parts of the question that are not on topic on this site. You can still see them by clicking "edited" above the owl avatar. You might try and ask the removed questions at the SE softwareengineering.stackexchange.com site. These are rather introductory questions, following some kind of course / buying a book would probably also help you. Starting with development and studying the theory later is generally not the best way to go about this. – Maarten Bodewes May 5 '20 at 14:03
• @MaartenBodewes Thank you, sure. They are my primary questions. But I understand the limited practice of Blockchain at the moment and I am guessing I most likely won't get any answer anytime soon, right? – Hassan Althaf May 5 '20 at 14:05
• Blockchain is practiced quite a lot, even though the hype is a bit subsiding. However, before the bitcoin and especially ethereum site allowed these kind of questions. Possibly for that reason we're not having all that many experts over here that answer questions - even if they are related to cryptography which is used by blockchain. – Maarten Bodewes May 5 '20 at 14:06
• @MaartenBodewes Ohhh, it's very limited resources to learn these stuff. Guessing the knowledge is too limited? – Hassan Althaf May 5 '20 at 14:07
• Well, the knowledge (or interest) is limited here, but if I put in "blockchain book" in my fave search engine then I get plenty of hits. – Maarten Bodewes May 5 '20 at 14:09

2. The hash of the current block is the hash of the data in the current block and the hash of the previous block (i.e. $$B_i = h(B_{i-1}, \{tx| tx \in B_i\})$$). So what happened when you modified the data in block $$B_{i-1}$$? $$B_{i}$$ will change. If you understand how $$\mathsf{git}$$ works? it's very similar. It's more interesting to see how the network agrees on a single chain.