Homework on Public and Private Keys - Questions

Blockchain and Bitcoin 101
#2641

  1. The private key is my own personal key. I can make a public key from the private key and broadcast it. Anyone can send me a message and use my public key to encrypt the message. Only the person with the private key can decrypt that message. I had better keep my private key safe!

  2. Public keys can be used to encrypt messages or for digital signatures.

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#2642
  1. Describe the concept of public and private key with your own words.

At first you generate a random number. This is your private key (you never lose or share it).
Then you create a public key which you can share to every body.
It is not possible to calculate your private key from your public key (hash function)

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

Encryption of messages and digital signatures

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#2643

1.Your computer will generate a large number which is then used to make a private key, this then has a function formula applied to create a public key which is derived from the private key. So if person A wants to encrypt a message to person B, person A will encrypt a message using person Bā€™s public key so that only person B can then use there private key which relates to their public key to decrypt that message.
2.2 use cases for public key cryptography are encryption like in the above mentions scenario and secondly digital signature which are used for bitcoin for signing transaction. Transactions are signed using you private key so that they can be verified on the network by cross referencing with the public key to prove you are the owner and you legitimize that transaction . In the creation of a new private key derived from a vast number generated from you computer a public key is also derived from the private key these together make your BTC wallet address.

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#2644

  1. A private key is a random number generated by a computer. The private key is used to generate a public key, which is obviously visible on a public network. The public key can be used to verify mathematically that it was generated by the private key and not somebody else. It is impossible to determine the private key from the public key. You can go from private key to public key, but never the reverse.

  2. Encryption, which is useful for private messaging. The recipient of a message has generated a unique private key at random. This is used to produce a public key. The author/sender of the message then encrypts their message using the recipientā€™s public key. The message is scrambled and impossible to read. The only person who can unlock the message is the recipient, whoā€™s private key can decrypt the message that was sealed using their public key.
    Digital signatures, these are used by the Bitcoin network. When you have 2 people interacting, the person sending the message (or sending Bitcoin, for example), signs the message. This is a digital fingerprint, signed using the senderā€™s private key. When the recipient gets the message, they can verify the sender mathematically, by comparing the digital signature used in the message, with the public key of the sender. Again, they cannot see the private key or work it out, but they can verify that it was used, exclusively, and the message could not have been signed by anyone else.

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#2645
  1. Public and Private keys make it possible to send a transaction (message or coin) through a public domain to a specific individual. It creates a link from the sender to the recipient in such a way that only those two individuals have access to the transaction.
  2. Public key cryptography can be used in encryption and digital signature. Encryption enables a transaction to be received by only the intended recipient. Digital signature verifies that the sender is who they claim to be so that the transaction is secured.
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#2646
  1. Private key is a randomly generated number, a public key is created.
  2. Encryption and digital signature
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#2647

1. Describe the concept of public and private key with your own words.
A private key is a randomly generated unique number used for generating a public key. The reverse process is impossible. This allows such pair of keys to be used for encrypting messages and achieve privacy, security, integrity and identification.

2. What 2 use-cases can public key cryptography be used for?
Encryption (private messaging and communication) and digital signatures (verifying who sent a particular message).

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#2648
  1. Describe the concept of public and private key with your own words.

random numbers are generated and called private key.

then public key is generated through private key.

Private key is secret while Public key can be known by everyone in the entire network.

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

  2. In encryption: The sender combine the public key of receiver with the secret message, encrypt it in the public network.

  3. Digital signature: Senderā€™s digital signature (which is generated by private key of sender) and senderā€™s public key work together, in order to verify the transaction.

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#2649

  1. Private key is main password that you donā€™t give out to anyone. That private key makes a public key for anyone to communicate with you but there is no way that you can find out the private key from the public one.

  2. Encryption and digital signatures are the two major use cases.

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#2650
  1. The private key is a random, very long string of numbers, that is near impossible to guess, it is for the private key keeper only, and if not lost or disclosed to anyone ,guarantees the assists recorded on the key.
    Public keys are generated from the private key so as the owner can trade from the private key with no other parties being able to guess, or corrupt the private key.
  2. For receiving and transmitting data, as proven through the trade on the blockchain network and various ecosystems.
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#2651

  1. Describe the concept of public and private key with your own words.
    The concept of a Private Key is the generation of a random number. With this private key, a public key can be generated mathematically.

  2. What 2 use-cases can public key cryptography be used for?
    A. Proof you are the author of a written piece of work.
    B. Proof you are the signer to a financial transaction.

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#2652
  1. Analogy: Public key is like the information on a thumb drive given to a spy A (anyone can see it or open the thumb drive). The private key is the encryption code only sent from spy Z to the intended spy A so only they can decode the info (which will look like gibberish to anyone without the private key.)
  2. Credit card sales confirmation number & information on the chip of my work ID which gives me entrance into areas forbidden by others.
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#2653
  1. Public and private keys are a security system that encrypts a message based on a public key, which a private key can unlock.
  2. Encryption and digital signatures.
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#2654
  1. Analogy: Public key is like the information on a thumb drive given to a spy A (anyone can see it or open the thumb drive). The private key is the encryption code only sent from spy Z to the intended spy A so only they can decode the info (which will look like gibberish to anyone without the private key.)
  2. Credit card sales confirmation number & information on the chip of my work ID which allows me entrance into areas forbidden by others.
#2655

  1. Describe the concept of public and private key with your own words:
    A private key is a randomly generated number from your computer. This number will belong to you and nobody else as itā€™s statistically impossible for two computers to generate the same private key. A private key is used to generate a public key which can be shared publicly. Public keys are able to help either encrypt messages that only the holder of the private key can decrypt or to verify transactions along with a digital signature. It is impossible to decipher the private key from the public key so it is of paramount importance to keep your private key to yourself.

  2. What 2 use-cases can public key cryptography be used for?
    Public key cryptography can be used for encryption and digital signatures. Encryption is a way to send messages from one person or entity to another without others being able to read them. Only the holder of the private key that generated the public key encryption can read the message. Digital signatures are used to verify who sent a message or transaction. A digital signature in combination with a public key can be mathematically checked to verify who sent a message or transaction.

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#2656

To be honest Iā€™m not sure how these cards work, but I donā€™t think they use public key cryptography they usually rely on a centralized server to authorize your access and the card is more like a password on the website.
Public key cryptography is used when you get a digital certificate that you can then use to login to an online bank or use e-government features.
As for the question you can use it for either encryption or digital signatures. :slight_smile:

#2657
  1. Private key is used to create Pubic key - always, never the other way round. Private keys are also used to decrypt messages or as digital signature. Public keys are used to create wallets or encrypt messages. And obviously Private key - is kept secret never to be shared and Public is open to see for everyone.
  2. Encryption, Digital signatures
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#2658
  1. Describe the concept of public and private key with your own words.

Private key its Created by Your computer and from there you will generate your Public key as well as your Digital Signature

  1. What 2 use-cases can public-key cryptography be used for?
    they are used for digital signature and encryption
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#2659

  1. For encrypting a message, the sender can use a random sequence of character to encrypt the message, this random sequence is called private key. For decrypting the encrypted message by a receiver who received it through a network needs a unique key from sender. This unique key is made from the private key of sender and sender publish this public key to intended people who can decrypt the message using public key.

  2. a. Encryption: To securely send and receive messages in an unsecured network Only the intended people can decrypt the message with a valid public key to read it.
    b. Digital Signatures: Using public key of a sender, the receiver can verify whether the message was indeed from the intended sender.

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#2660

Messages are encrypted with a public key and only the owner of the private key can decrypt it.
With digital signature you use the private key to sign the message so others can authenticate it with the public key. :slight_smile: