Homework on Public and Private Keys - Questions

Blockchain and Bitcoin 101
#1511
  1. Describe the concept of public and private key with your own words.
    A private key is used to create a public key and this is a form of encryption. The public key can be shared with anyone as nobody can find your your private key through it but you can find out the public key by knowing the private key.
  2. What 2 use-cases can public key cryptography be used for?
    It is used for encryption, you can encrypt a message with your public key and it can only be read by the person that has the private key belonging to the public key.
    Digita signature is another use case that is more secure than the first example as it also requires a digital signature of the private key.
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#1512

Digital signatures are not much more secure than encryption. Its just a different use case where one is to send private messages and the other to sign a public message that others can verify its authenticity. :slight_smile:

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#1513
  1. public key can be visible and shared over network to to encrypt message, private key is best to keep hidden and use for decrypting messages
  2. encrypting messages and digital signatures
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#1514

  1. The concept of a public and private key is used to protect and/or verify certain data. Depends on the use case, your computer/wallet etc. creates private key that is protected and just for you to use. Then the public key is created from the private key in an irreversible way that is shared with the network.

  2. Public key cryptography is used for encryption and as a confirmation of a digital signature. In the first case, for example, “A” send message to B using B public key which can be decrypted only by the B’s private key.

In the second option, as a confirmation of a digital signature, “A” sign the data with its own private key and B confirms the signature by using A’s public key.

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#1515
  1. Like the hash function, another irreversible mathematical process is used to create public keys from randomly created private keys. The private key can never be reverse generated from the public key. Because of this attribute, the private key can be used to sign encrypted messages.
  2. Signing encrypted messages and authorizing the expenditure of crypto currencies.
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#1516

Can you figure out what process this is? :slight_smile:

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#1517

Are signatures made using private keys only?

#1518

Yes, you sign a message using your private key and others can verify (using your public key) that you were the one that signed it.
Like those old seals seals that were used in the past by royalty. :slight_smile:

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#1519

A private key is random generated numbers that are private. From this private key is generated a public key, which is also random generated numbers that are public and known to everybody. These two keys are mathematically related. These keys can be used to encrypt and decrypt messages.

Two use-cases that public key cryptography can be used for are encryption and digital signatures.

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#1520

  1. Public keys are made available to everyone in the public domain, and it’s used as a unique address that people use in order to communicate with you or send you crypto. The private key is also unique to you, and is used to mathematically generate the public key. The private key should be protected and is used by the owner in order access private messages or crypto on the corresponding blockchain.

  2. Encryption - Private messages sent to someone using their public key are encrypted so that the only way it can be understood is with the private key.

Digital Signature - When you send cryptocurrency on blockchain, it can only be authorized by digitally “signing” the transaction with the corresponding private key. Likewise, the receiver can only access the cryptocurrency by “signing” for it with their own private key.

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#1521

Describe the concept of public and private key with your own words.
A. Public and Private keys allow you to send and receive encrypted messages and also to
digitally sign encrypted messages.

What 2 use-cases can public key cryptography be used for?
A. Encryption
Digital Signatures

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#1522

  • Describe the concept of public and private key with your own words.
    A public key/private key pair consists of a totally random number that is used as the private key. The public key is derived from the private key via a has function, so there is no way of calculating the private key given your public key. If the owner of the private key keeps that key a secret, then the public key can be used by everyone else.

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

  1. Encryption
  2. Digital signatures
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#1523
  1. Private key is like your secret password. Only you should know this key. From this private key, a public key is generated. This is for public view and anyone can know this. The public key is for receiving data from another person. The private key is for signing and authorising the release of the sent data from you to the next person.
  2. Uses cases are: 1) Encryption of data and 2) digital signatures
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#1524

Homework on Public and Private Keys - Questions
1. Describe the concept of public and private key with your own words.

   The public key is generated with your private key, once the public key is generated you will share it with your participant to exchange information, for example in a encrypted chat session where you add your public key to the message, when you receive an answer back the message are encrypted with my public key, in order to read the message I need to have my private key, the same that was used to generate the public key in the first place.
   The private key must be kept secret from all other, write it down on a paper and store it in a safe location and or in multiple location in case of fire, don’t ever have private key’s in your computer to be secured from hacker that eventually can gain access to your hard drive/usb stick without your notice.    
   
2. What 2 use-cases can public key cryptography be used for?
   One case can be in a encrypted chat session where you add your public key to the message and the receiver will encrypt the reply with your own public key.
   And for bitcoin transaction when using digital signatures, to validate that the correct user was signed the transaction, as the receiver can check signature with a mathematical formula that signature actually comes from the private key generated from the public key given in the message.
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#1525

1: Your computer can generate a random number, which is your Private Key.
This Private key can generate a Public Key, which can be shared. No-one but you will be able to derive your Private Key from your Public Key, so it can be used to verify identity and message integrity

2: Encryption & Digital Signatures

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#1526

Encrypting with one key requires decrypting with the other. That works both ways. These two keys are used together to encrypt and decrypt a message. If someone encrypts with my public key, then only i, with a safe and secure private key, can decrypt it.

Anyone can send data securely to the private key owner. Also, anyone can verify that data they receive from the owner of the private key is actually from that source, and not from an impersonator.

It is used for Encyption and for Digital Signatures.

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#1527

As you already know that these two keys are mathematically related it makes sense that the public key is not really a random number. It is a number derived from the private key :slight_smile: It just might appear as a random number.

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#1528

1 Describe the concept of public and private key with your own words
Public key is for everyone and private is only for the “owner” and private key can “read” public key but not vice versa.

2 What 2 use-cases can public key cryptography be used for?
Encrypting messages. of some kind. and digital signature

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#1529

The public and private keys in Bitcoin are a unique type of encryption which uses several technologies; combined to produce unique digital keys for the user. The private key is first generated using the SHA256 algorithm. From there, the result is multiplied by itself and plotted on the secp2561 elliptical curve. Once the final resting point is completed, the X and Y values are hashed together again, where Y can be either positive or negative. This is done through the SHA256 and RIPEMD160 algorithms, resulting in a shorter address and in this way, the public key is generated. It is then re-hashed through base58, adding greater security and usability. This extra hash adds a checksum, a self-correcting feature that checks for mistakes and gives it an additional address in the front of the hash. It is hashed one more time through base58 and this becomes the final user-friendly Public Key address.

Two cases where public keys in cryptography be used for is when a user wants to keep information private and or create a digital signature for exchanging information, assets, etc, on the blockchain.

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#1530

I. The public key is a string of random numbers and can be used to encrypt a message, or a transaction which only the intended recipient can decipher and read by using the associated private key, which is also made of a long string of random numbers. The private key must remain known only to the recipient. The key pair is mathematically related so that whatever is encrypted with a public key can be deciphered using the private key.

  1. Public key cryptography can be used for messaging or transactions.
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