Homework on Public and Private Keys - Questions

Blockchain and Bitcoin 101
#2416

  • Describe the concept of public and private key with your own words.
    A private key is a random string, kinda like a password.
    A public key is mathematically derived from the private key in such a way that, the private key can not be determined from it so it can be publicly shared and used to encrypt information that only the private key can decrypt.

  • What 2 use-cases can public-key cryptography be used for?
    Public-key cryptography can be used for encrypting information for a public network securely, no need to risk someone intercepting the keys and decrypting it.

It can also be used for digital signatures, and authentication.

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#2417

  1. Public and Private key are generated numbers which come in pairs. First, the private key is randomly generated and it can be a combination of numbers, letters and special characters. The Public key is derived from the Private key, where the Private key is used as a so called scalar (or a multiplier) by which a point (with coordinates (x,y)) on an Elliptic Curve is multiplied PrivateKey number of times and after each multiplication reflected over the x-axis. The Private-Public Key concept is used for Encription and Digital signatures, where the Private Key should be only known to the owner of the Private/Public key pair, and the Public key is available for everyone as it helps with validation of Digital signatures and sending the messages to a particular entity.
    (a nice intro article to Private/Public keys https://medium.com/coinmonks/private-and-public-key-cryptography-explained-simply-4c374d371736)

  2. a) we can generate addresses to receive messages/transactions with a public key
    b) we can use public keys to check the validity of signatures of the senders of messages/transactions and we can use public keys for sending secure messages to a specific destination.

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#2418

  1. A public key is a number derivated from a private key necessary for the encryption process of sharing information privately.

  2. Encryption and digital signatures

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#2419
  1. a private key is a randomly generated number. When hashed, it creates a public key. A publicly key, is shared publicly for making and receiving payments. Your private key is used to authorize payments and as a result, are kept secret. Private keys are also used to sign transactions, confirming to the network that the actual person responsible for the public key, is authorizing the transaction.
  2. public and private keys are used in encryption and digital signing
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#2420

  1. Private key, is a random number, with it you can create a public key or sign messages/transactions and decrypt information sent to you decrypted with your public key. Itā€™s important not to show the private key to anyone. The public key is shared with everyone and is mostly used for encrypting messages when sending sensitiv information to the private key holder.

  2. Encreption and Digital identity(signatures)

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#2421
  1. Describe the concept of public and private key with your own words.
    Public Key is generated out of Private Key. With the Private Key you can decrypt encrypted data which is encrypted by using your Public Key. The Public Key is used by the opponent, while the Private Key is secret and is only used by your self.
  2. What 2 use-cases can public key cryptography be used for?
    Encrypt data.
    Validate signatures.
2 Likes
#2422

  1. Your private key is a randomly generated string of numbers and letters that only you know. Your private key generates a public key that everyone can see. Your private and public keys work together as a pair to encrypt and decrypt transactions as well as create a digital signature.

  2. Public key cryptography can be used for both encrypting messages and creating digital signatures.

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#2423

A public key is an address that can be known by anyone on the network. This is necessary for anyone who wants to send or receive encrypted information. A private key is unique to each crypto address and is only known by the address holder, which they must use to sign an outgoing message they wish to encrypt or to have to unencrypt a message sent to to them! If the private key is lost, any encrypted messages sent to the public key associated with it, cannot be decoded without it. Thats why its important you never lose your private keys or let another person find out what it is. They would control your bitcoin then.

Public key can be used an an address that others can contact you with their encrypted messages. Allows transactions to take place securely from others, and requires no counter party risk or third party to be trusted with the information being sent an in intermediary. It is trustless.

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#2424
  1. Mathematical operations are possible that use the relationship between numbers and mathematical transformations to prove a connection between these numbers. This is the basis of modern encryption techniques. A public key can decrypt a message encrypted with a private key. Private keys are secret keys used by individuals to encrypt messages (just perform mathematical operations on them basically) and the public key, which is made publicly available, can decrypt that message. Only the associated key can do these tasks, never any other.
  2. For message encryption - to ensure the integrity of secret messages - and digital signatures, which are a method to verify that a ā€˜messageā€™ received (which can be an actual message, or it could be a file or something else) were sent by who they were supposed to be sent by. To confirm they are genuine and not corrupted or altered, either accidently or maliciously.
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#2425

  1. A public key is a random string of letters that belongs to you that everyone has access to. Private keys are the same thing but no one has access to yours except you.

  2. They can be used when you want to send a private message to someone but you donā€™t want anyone else to see it or when bitcoin gives you your address.

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#2426
  1. a private key is a randomly generated number. that number runs through a formula to create a public key. people can use your public key to transact with you. as long as you have your private key you can access the data sent in the transaction.
  2. encryption and digital signatures.
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#2427
  1. Public key is a derived from the private key from a special formula after a random computer guess that is public for anyone to use to send encrypted message or send transaction and the private key that derives the public key decrypt the message or can be used for using the sent transaction on an open source network

2.Public key cryptography is use for encrypting message and used for digital identification especially in bitcoin network.

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#2428

Describe the concept of public and private key with your own words.

  • The private key is only known to the user, the public key is displayed in public. It is 1 way in that a private key can generate a public key.
    What 2 use-cases can public key cryptography be used for?
  • Public key cryptography can be used for encryption and creating a digital signature.
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#2429

Public key is just seemingly random but it is derived from the private key. :slight_smile:

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#2430

Dear Elena. I see your post was already checked. We both have different answers on Q2. So as always firstly i doubted on my self :smiley: . But if you could create a signature out of a Public Key, everyone could create any signature :slight_smile: . With a PUBLIC KEY you donā€™t create a signature, you verify the signature sent to you. The PRIVATE KEY creates digital signatures.
Have a nice day! Thomas

#2431

She is referring to public key cryptography which is the technical term for public and private keys.
With it you can either encrypt/decrypt messages or create/validate signatures.
Thatā€™s why I consider both of you are correct :slight_smile:

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#2432

  1. Private key is a random numbers generated by a computer, and Public key is derived from the private key. This is a one way function, meaning it is impossible to trace back to generate private key from the public key. Public key can be shared with everyone, and everyone can use the public key to encrypt the message, but the encrypted message can only be accessed by the owner of private key.

  2. public key cryptography can be used for encryption, and as a digital signature to sign a transaction.

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#2433

  • Describe the concept of public and private key with your own words.
    a private key is a generated string (random number) only for me to keep in a safe place
    a public key is derived form the private key and can be shared with anyone
    is not possible to get the private key from the public key

  • What 2 use-cases can public key cryptography be used for?
    1.encryption of data - sender encrypts the data with recipients public key and the recipient decrypts the data with his/her private key
    2.digital signature - sender signs the data with his/her private key and the recipient verifies the signature with senders public key

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#2434
  1. The private key is a very long, random number, generated by your computer. It is kept with the owner and no one else has access to it. The public key is generated from the private key by a certain formula and can be seen by anyone. It is created in such a way that it is impossible to go backwards from the public key to the private key. When you send your public key, other people can tell that you know the private key (so it is authentic), but they cannot actually see what the private key is.
  2. The two use cases are encryption (when you want to send a message privately) and digital signatures (used every time you send a transaction).
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#2435

https://www.youtube.com/watch?v=xxfUpIV9wRI&ab_channel=aantonop

This explains the elliptical curve concept - really interesting! By Anton Antonopolis.

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