Homework on Public and Private Keys - Questions

Blockchain and Bitcoin 101
#1431

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

A private key is an enormous random number that can be used to identify a device or entity, and to allow for the secure transfer of information that is applicable only to this entity.
This is achieved by generating a public key that is unique to the private key, that can be made publicly available with no risk, to be used for encryption purposes by the sender.
The public key can only be used to encrypt information and never decrypt information. Only the private key associated with the public key is capable of decrypting the information.
The public key can also be used to confirm that any signed message claiming to be from the private key, is in fact the case.

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

To encrypt data that needs to be sent to the public key owner (identified by the private key),
and to verify that a signed message was in fact signed by the owner of the public key.

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#1432

  1. A private key is a random string, a public key is derived from the private key through a hash function, this private key can be shared securely hence no input (private key) can be inferred from such output.

  2. It is used in end to end encryption and in digital signatures to certify identity and integrity.

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#1433
  1. Private key is a randomly generated number (very large and complex), which needs to remain secret. From this number, a public key is derived. Public key is see by all participants of the network.
  2. Encryption and digital signatures.
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#1434

  1. The PrK is in fact the input in the function. It is a very large random number that is generated by a computer and allows to ā€œsignā€ a message/transaction. This number is than used to generate another large number -the PuK- which is shared with the public and allows A and B to share messages. When A uses the public key of B to send information (message, transaction etcā€¦) only Bā€™s private key (derivated from its public key used by A) is capable of decrypting the information.

  2. The 2 use cases are encryption and digital signature

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#1435
  1. Describe the concept of public and private key with your own words.

Two keys are used, but they are mathematically linked and form a key pair. The public key can be shared with anyone, the private key must remain secret. Only one of the two keys is used for decryption, the other is responsible for encryption.

  1. What 2 use-cases can public key cryptography be used for?
  1. Encryption -> Protect the content
  2. Digital Signatures -> Identify integrity
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#1436
  1. Describe the concept of public and private key with your own words.

A private key is a key that should be stored safely / protected from any other party accessing it. The public key is a hash of the private key. Like this, it is possible to confirm the authenticity of a message using the public key while not having to reveal the private key.

  1. What 2 use-cases can public key cryptography be used for?
  • Encryption of files and messages between two parties
  • Signatures (authentication) as used in cryptocurrencies
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#1437

A public key is a publicly identifiable address generated from a private key. A private key is a randomly generated number. The private key is used to access the public key, but never vice versa.

Public key cryptography can be used for encrypting a message using someone elseā€™s public key. Alternatively, it can be used to digitally sign a message publicly using the the senderā€™s private key.

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#1438
  1. if we think of the bitcoin network as a giant warehouse of small cubicles, the private key is a random computer allotted cubicle key. once ā€œunlockedā€ by the private key , the cubicle gets a public address (a public key), telling all other entities on the network ā€˜whereā€™ it is. the owner of the private key can share the public key to anyone, data can come from outside directly to that public cubicle, but only the owner of the private key has legitimate access to it. for analogy sake, sort of like a mail box, using the public key you can ā€˜deliverā€™ something into the mail box, many entities can deliver into the same mail box. but only the private key owner can open it at the end of the day and has access to all the ā€˜mailā€™.
  2. public key cryptography can be used for encryption of data sent from one entity to another, so only the receiver of the data sent to a certain public key or address, can read it using their paired private key.
    it can also be used by the receiver of data to check if received data was actually sent by the public key owner. this is called digital signing, and if the sent signature and public key of sender do not correlate, it is assumed the signature is fraudulent; if the signature and public key of the sender correlate, showing them to be made from the same private key, it can be concluded that the signature is true
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#1439

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

The public key encrypts information and the private key decrypts the information that was encrypted with the the public key.

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

Public key is used for Bitcoin transactions and the public shared so Bitcoin can be sent to that address. The private key allows access to the bitcoin sent to the public key.

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#1440

The private key is a unique key to the user and thanks to that key the user is able to decrypt the message. Messages from that user are also encrypted using that same key.
The public key is the key that is derived from the private key and it is used to send data over unsecured network. That key is visible to the public.
It is not possible to find out the private key knowing the public key.
Losing private key makes it impossible to get the messages sent using public key.

Two use cases are: encryption and private signature.

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#1441
  • Describe the concept of public and private key with your own words.
    its a secure one way system that that enables users to send private messages to a specific point.knowing both sender and receiver are the intended targets.
  • What 2 use-cases can public key cryptography be used for?
    encryption and digital signatures.
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#1442

1._ public key is the result of the private key made to the mathematical computer number and is used to recive encrypto messages and digital sign in.
Private key is a random number, what is used to decrypt the messages with the private key.
2._ can be used to digital sign in and in the encrypt messages process.

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#1443

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

To me, public and private key are just like what a hash function does. A private key is the input, and the public key is the output, and the output cannot lead back to the input.

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

Encryption and digital signature.

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#1444
  1. Describe the concept of public and private key with your own words.

A private key is a random number generated for a specific entity (person, account) from this private key a algorithm can generate a public key. when someone wants to send a encrypted message to a recipient, once must encrypt the message with the public key of the recipient in order for the recipient to decrypt the message (using the private key)

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

Digital signature and encryption.

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#1445
  1. Describe the concept of public and private key with your own words.

Using random numbers, you can generate a private key that is personal to you which should at all times be kept secret. From your unique private key you can generate a public key that can be shared on an open network that can be used for multiple forms of communication between two or more parties. The important part is that the information sent to the public key can only be accessed by the owner of the private key that generated it. Thatā€™s why itā€™s so important to keep your private key safe, and never show or store it on an open network.

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

Public key use cases have proven to be effective for open network encryption along with digital signatures that provide a verification of trust to the recipient of the signature.

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#1446

A public key is generated from your private key. The private key keeps your information safe. The public key is used to verify transaction are being generated from you or to send you specific data.
Use cases are encryption and digital signatures.

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#1447

  1. Describe the concept of public and private key with your own words.
    They work together as a pair in a transaction. A private key can be used
    to encrypt a message or be used as a digital signature. A public key is used to decrypt messages or as a public address people can use to send transactions to your wallet.

  2. What 2 use-cases can public key cryptography be used for?
    Encryption and digital signatures. Sending messages or in bitcoin / cryptocurrency transactions.

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#1448

  1. The private key is a string of digits generated by your computer/wallet, that only you are supposed to know (like the PIN of your card). The public key is derived from the private key and is also a string of digits. This is public and everybody can see it (like the IBAN). These two keys work together to encrypt or to sign messages or transactions.

  2. Encryption and digital signatures.

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#1449
  • Describe the concept of public and private key with your own words.

A private key is a user generated code that appears to be random and disorderly which are then used to generate a public key; Note, key production only works in this order, public keys cannot generate private keys.

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

This key system facilitates a secure message channel in two ways.

1- Publicize the public key so people can encrypt messages with it and send them to the individual who owns the private key.

2- Publicize the public key and sign a message with the private key and a name so the receiver will know that the message came from the person who claims to have sent it because the public key and private key match. The reason why Iā€™m saying that the sender has to attach a name is because what happens if 10 people publish the public key claiming to be the sender? Attaching a name verifies the name as the owner of the private key i.e. the sender.

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#1450

It is similar :slight_smile: but we donā€™t use hash functions to derive public keys but elliptic curve which is also a one way function.

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