Homework on Public and Private Keys - Questions

Blockchain and Bitcoin 101
#1591

  1. Public and private key in my own words, your public key is as it sounds its public everyone can see it everyone can access it. your private key is as it sounds its private and only you yourself have access to it.
    you can use your private key to generate a public key but no one can use your public key to access your private key.

  2. two use cases public key cryptography are Encryption, and Digital Signatures

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#1592
  1. A private key is held by the receiver and kept secret. The public key is derived from the private key, and the public key is then used to encrypt the traffic being sent by the sender. The receiver’s private key is then used to decrypt the encrypted message from the sender.
  2. Public keys can be used to send emails, or interact with APIs.
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#1593

True, but these are both examples of encryption :slight_smile: Can you figure out another more basic use?

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#1594

1.- The private key is your major personnal code which has to be secured and kept secret. It generates a public key which can be used by anyone to send you encrypted informations. Once you received informations encrypted with your public key from another person, you can then decrypt it with your private key.
2.-
a) Encrypt the informations you want to send to a person with his public key
b) Use the public key from a sender to check his digital signature which was generated from the private key from this last one.

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#1595

  1. Describe the concept of public and private key with your own words.
    A private key is a very large randomly generated number, which can be used to generate another random number called a public key. Anyone who wants to send an encrypted message to the owner of the private key can use the public key to encrypt that message and only the owner with the private key can decrypt and read that message.

  2. What 2 use-cases can public key cryptography be used for?
    Encryption and digital signatures

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#1596

  1. Describe the concept of public and private key with your own words.
    A private key is a very large random value generated by your computer. With this private key we can mathematically derive a unique public key. However, the private key cannot be derived from the public key. The public key can thus be shared without any danger of the related private key being exposed or the possibility of someone deriving the private key from it. This is crucial to the use of public/private key pairs.

  2. What 2 use-cases can public key cryptography be used for?

Encryption: A use case is the sending of encrypted messages on public, unsecured channels. Here the sender encrypts the message using the recepient’s public key. After receiving this encrypted message, the recipient decrypts it using his private key. However, in this method, it is possible for a 3rd person to maliciously use someone’s public key and pretend to be that person sending the message.

Digital signatures: This is a crucial component in the execution of crypto transactions. After generating a private/public key pair, the user can use the public key to generate a wallet address. A wallet address is a shorter representation of the public key. It adds an additional layer of security. It is not possible to derive the public key from the wallet address. When a user sends funds from his wallet, it is signed using the private key (without exposing it). Since the signature is treated using the private key, no one else has access to it, confirming that the authorized user is indeed the signatory. This digital signature signals ownership/authority over funds to the network which then recognizes the transaction as authentic by mathematically comparing it to the users public key.

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#1597
  1. sending encrypted messages over an unsecure connection.
  2. Sending a message or sending funds.
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#1598

  1. A private key is a random number that must be kept secret at all times if you want to keep your data and/or internet activity secure. A public key is generated by your private key, and can be shown to anyone. The mathematical operations that generate your public key from your private key are a one-way street and cannot be reversed (unless we crack prime factorization).

  2. Public key cryptography can be used for encryption as well as to provide a digital signature to, for example, pieces of work or transactions.

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#1599
  1. I like that analogy, where pubkey is as account number and privkey is as password. Both of them with more functionality of course. As encryption, signing messages, deriving new addresses.

2)Encryption and digital signature

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#1600

  1. Asymmetric cryptographic system uses pairs of keys: public keys, which may be distributed widely, and private keys, which are known only to the owner. The generation of such keys depends on cryptographic algorithms to produce one-way functions. Effective security only requires keeping the private key private; the public key can be openly distributed without compromising security. In such a system, any person can encrypt a message using the receiver’s public key, but that encrypted message can only be decrypted with the receiver’s private key.

  2. Public Key Cryptography is normally used for 2 main purposes:
    a) Encryption - when sending sensitive information to ensure privacy
    b) Digital Signatures - to identify yourself and ensure integrity of message. This is critical technology used in Bitcoin wallets where Private Keys are used to generate Public keys and subsequently Bitcoin addresses. This is also a one way system where Private key cannot be derived from Bitcoin address or public key - in all cases security of system is dependent on secrecy of Private Key.

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#1601

[quote=“ivan, post:1, topic:8431”]

  • Describe the concept of public and private key with your own words.
    A private key number is randomly created. From that Private Key, a Public Key is mathematically created. You can not use a Public key to arrive at a Private Key.
    You encrypt a message with the public key of the recipient. The recipient then decrypts the message with his private key.

  • What 2 use-cases can public key cryptography be used for?

The use-cases that public key cryptography are;
1- for encryption
2- for digital signatures. When digitally signed with the secret key of the sender, the recipient of the message can confirm it was actually signed by sender, when the recipient uses the public key of sender the confirm signature.

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#1602

Public key is shared and is used to send Bitcoin. Private is private to one person and no one can see it unless someone steals the private key.
2 Public key can be used for encryption and digital signatures

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#1603
  1. The public key is a unique virtual address that you can share with others. This allows people to encrypt data with your key and only you can open it with your private key. Your private key is a random number that is generated and that you can use it to decrypt those messages and digitally sign them.
  2. The two use-cases of a public key are for people to send you encrypted messages and also for allowing people to verify if your signature is authentic.
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#1604

  1. Public and Private keys are developed to encrypt a transaction or communication between 2 parties, to ensure personalisation, security and privacy.

  2. Private keys are used in cryptocurrencies eg. Wallets produce a private key when downloaded on your computers, public key is produced to display to second parties who you wish to transact wit.
    Private keys can be produced to execute smart contracts and also encrypted communication between two parties… (I know thats three)

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#1605

1.Private key is private, when sending bitcoin you are giving your signature with the private key to confirm the BTC is coming from your address. If someone gets hold of your private key you can loose your crypto.
The public key is public, used for receiving private messages to you that you can open with your private key.

  1. Receiving private messages and crypto basically.
    Right?
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#1606
  1. The Public Key is for public viewing, the Private Key allows the holder to decrypt the Public Key pair.
  2. Used for a Bitcoin Wallet and for message encryption.
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#1607
  1. in the public /private key concept you own a private key that only you know with that you can generate a public key which you can give to the world to prove that you have access to the private key.
  2. the public key can be used to encrypt messages and to validate signatures.
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#1608
  1. A public key is a key derived from your private key that you can place anywhere. A private key is something that you should only keep to yourself because (1) it is irreplaceable, once it’s lost, it’s lost (2) it contains your coins so if someone steals it from you then you can never get your coins back.
  2. Public key cryptography can be used for transactions and as a digital signature.
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#1609

Thank you for clearing that up for me!

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#1610

Not really, because making transactions and executing smart contracts are both examples of digital signature :slight_smile:

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