Homework on Public and Private Keys - Questions

Blockchain and Bitcoin 101
#1311

No problem. Keep up the great work. :smiley:

#1312

In bitcoin we mostly use digutal signatures. However I see you did additional research. :slight_smile:

#1313

Homework on Public and Private Keys - Questions

1. Describe the concept of the public and private key with your own words.
The public and private keys are unique pairs that belong together. You can see your public key as a mailbox in your house and the private key to open it. Everybody knows your pubic address but the private key not. a public key is created out of a private key and the public key is a one-way function. It is impossible to get the private key from the public key. Public key is used to receive while private key is used to read or make signatures.

  1. What 2 use-cases can public-key cryptography be used for?
    A public key can be used as an address.
    The public key is compared with the signature and data from the private key.
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#1314

Hello Mauro,
Yes I would like to get more information concerning elliptic curve cryptography. My background in IT is limited but I am fascinated with blockchain technology and am trying to learn as much as I can.
Thanks again for your input! :+1:

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#1315

  1. Describe the concept of the public and private keys with your own words.
    Ans: The public key is a derivative of the private key and the public key is what everyone can see. The private key is for your eyes only and should be kept secret.

  2. What 2 use-cases can public-key cryptography be used for?
    It can be used to communicate privately and securely via email and public-key cryptography can be used to encrypt data.

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#1316

Hi Daniel,
Here is a very detailed site about the Elliptic Curve Digital Signature Algorithm: https://github.com/bitcoinbook/bitcoinbook/blob/develop/ch04.asciidoc

I believe this is from the book called “Mastering Bitcoin” by Andreas Antonopoulos. I highly recommend this book if you want to know all the details. You can’t go wrong with him. :smiley:

#1317

Don’t forget about the digital signatures. They are very important in bitcoin as they allow us to spend the funds from a public address, as long as we have the corresponding private key. For better understanding we can use a real life example. Let’s say I have a box with 1000$ but it is locked with a pin code (A box is a public address). The shop wants me to prove that I own the box before I can move anything out of it. I turn my back to the shop and enter my pin code (Making a digital signature by using my private key). After that the shop can verify (they see an opened box = valid signature) that I am the true owner of the box, and I never had to reveal my pin code (Pin code = Private key).

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#1318

1- The private key is a key you create yourself and share with no one, that is in fact the address to which your bit coins will be sent to. The public key is created from the private and in fact can be shared with someone in order to accomplish a transaction.
2- The public key has a relationship with the private key and can identify the recipient of the transaction. It cannot be used however in a reverse way to figure out the private key.

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#1319

This is know as making a digital signature. When we sign a transaction with our private key, we make a digital signature that can be verified by the miners without actually us ever having to reveal our private key. This enables us to prove the ownership of a bitcoin address. Because of that we are able to spend any remaining UTXO that the address has.

One more important use cause of the public and private key cryptography is encryption. Using your public key I can encrypt a secret message and send it across a public network directly to you. You can then decrypt the message using you private key. This means that only you and I know the message I sent you, since the public won’t be able to decrypt it. :smiley:

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#1320

  1. Private keys is the gateway to your wallet and public keys are used to send transactions after being signed by the private keys.

  2. Public keys can be used to send msgs or funds and can be used for encryption.

#1321

  1. A public key is derived from a private key. It is to be shared. But there is no way to use the public key to find the private key, because it is a one way function.

  2. Public key cryptography can be used for encryption (such as sending messages privately to others) as well as for identification (such as for digital signatures).

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#1322

Thank Mauro, good breakdown.

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#1323

1.Public key ,where everybody can know and see it,but private key only belongs to you,
and with that you can take actions,once you lose it you cannot recover,you lose your funds.
2.You can send and receive crypto on that address.

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#1324

Private keys are used to send funds, but others can use your public key to send you an encrypted message only you can read, or send you funds only you can unlock using your private key :slight_smile:

#1325

  1. A pair of public and private keys is a set of 2 numbers that are the basis needed to create digital signatures and encrypt/decrypt data. The private is usually a random generated number from which we derive the public key using a cryptographic hash function.

  2. As mentioned in the previous answer the 2 use cases are to sign data and encrypt or decrypt

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#1326

My Answers:

  1. Privates keys are generated for your eyes only and need to be keep secret at all cost. it can be used for Digital Signatures and Encryption. Public Keys are used to send messages on any public forum, but recipient will also need private keep to read.
    2 Encryption and Digital Signatures
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#1327

Answers:

  1. The concept of public and private key is used to eliminate 3rd party trust and achieve maximum security for a person to receive a message or funds. By doing so, a person has to generate private key to a wallet which that person has to keep it securely and safe from anyone. And now that person wants to receive funds from others. That person will then generate a public key from the private key and send out the public key address to another person who will be sending him/her the funds.

In this manner, the transaction will understand a verified that the it is the correct recipient based on the public key which matches the private key. In such aspect, it is considered genuine and authenticated thus proving it a secure manner to a transaction.

  1. A public key cryptography can be used to encrypt and verify digital signatures.
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#1328
  1. private key is a radom generated unique number, to be kept confidential. It functions as one´s signature.
    public key is generated through a formular based on the unique private key, and can be used to sent a message / transaction - or receive a message / payment
  2. Either for encryption, to protect a message from being accessable by another party than the one you are adressing. Or as Digital Signature in Crypto. There is no way to get from public key to the private key from outside.
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#1329

1.- If I want to send a message to someone and I want to keep that message private then the concept of public and private key it is quite useful.
The software that I’m going to use to send or receive a message, will create a large random number, that number will be my private key. This time I will take literally the meaning of the words “private key” so, I will keep those random numbers in a safe place and I won’t show them to anyone. However, If I want to communicate with the external world, I need a way to do it. That is the job of the public key, to keep me connected to the external world in case someone wants to communicate with me. So, my private key creates my public key to make it easy to people to send me messages. Since my private key creates my public key, there is a direct link between those. So as long as I keep safe my private key I will be able to access to the message that was sent to me through my public key.

2.- 1 Encryption
2 Digital Signature

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#1330
  1. Private Key: a randomly selected string to uniquely identify my Wallet . A public key is a secondary way of identifying my wallet (created from my private key) for public transactions. Offers the receiver of my transaction a way to verify my Bitcoin Address to make sure it’s me.
  2. Verifying identity of sender and where to send the coins. Where it came from and where it’s going.
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