Homework on Public and Private Keys - Questions

Blockchain and Bitcoin 101
#1251

  1. Describe the concept of public and private key with your own words.
    A. Public key is derived from your Private Key, and is what the world can see. Private Key is kept secret and is a randomly generated very large number, that uses digits and letters.

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

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#1252

Private and Public Keys

  1. Private key is randomly generated and is used to generate the public key. Data can be encrypted using the public key, but the decryption of it is only possible if you have the private key.

  2. Digital signature/verification and information encryption.

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#1253
  1. Describe the concept of public and private keys?
    Public key can be openly distributed without compromising security. A 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. What 2 use cases can public key cryptography be used for?
    a) To encrypt the message
    b) To be used as digital signatures
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#1254

  1. A private key is a unique number generated by your computer that is assigned to you specifically. It is a " secret code" that you can use to verify your identity (signatures), from which you can also un-encrypt encrypted messages that are sent to you. A public key is a key that you can put out in order to allow for communication with you. You can receive payments and messages from it. You cannot find a private key from a public key.

  2. Encryption, you can read a message formulated from your public key ONLY with your private key. Digital signatures, the power to do anything with your “account” and verify your identity or transactions.

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#1255

  1. A private key is a large random number generated by a computer; the public key is derived from the private key.

  2. Public key cryptography can be used for encryption and digital signatures.

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#1256

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

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

  3. Private key is a randomly generated number that is produced by your computer. From the private key the public key is created.

  4. Public keys are used to encrypt sensitive data, private key can be used to create a digital signature when sending a message. The receiver can verify the origin (private key) of message came from sender by using the digital signature and public key.

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#1257
  1. Describe the concept of public and private key with your own words.

A: A private key is a large random number that’s meant for personal use and shouldn’t be shared with others. A public key is generated from a private key and can be shared with anyone you wish and is also viewable by all interested parties.
2. What 2 use-cases can public key cryptography be used for?

A: Public key cryptography can be used for digital signatures and encryption

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#1258

  1. The public key is used as a “recipient address” to receive currency, as well as providing a “sender identity” if an encrypted message or currency is sent. A private key is a randomly generated number which is encrypted and secret. The private key generates the public key, and the private key also acts as a “digital signature.” When sending a message from your private key, it will act as that signature and the recipient can verify it because your public key will be shown as the “sender.” The generation of a public key is a one-way function, you cannot use the public key to duplicate the private key.

  2. The public key can be used as an address for other people to send currency to, but the sender is unable to use the public key to withdraw from your private key “account.” The public key can also be used as an identifier for a “sender” of a message or currency.

#1259
  1. Describe the concept of public and private key with your own words.
    A private key is randomly generated by your computer and can be shared with the public that the someone can use to encrypt data that only your private key can un-encrypt. The private can also be used to sign a digital signature proving it’s your wallet.
  2. What 2 use-cases can public key cryptography be used for? To send transactions and encrypted messages.
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#1260

  1. A private key is a randomly generated large number that must be kept secure by its owner. A public key is a known x,y coordinate on an elliptic curve multiplied by the private key. This public key can be verified by the private key but the private key cannot be deduced from the public key. This is called a “One Way” or “Trap Door” function. Bitcoin uses a second layer of protection in producing an address by hashing the public key first with SHA256 and secondly RIPEMD160 to produce a 20 byte output address, called a HASH160 public key.

  2. Public key cryptography is already used in bitcoin as proof of ownership of a bitcoin address, in encrypted messaging protocols and secure web pages.

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#1261

  1. Describe the concept of public and private key with your own words.
    The concept uses two keys to send messages in private. I can encrypt the message by my public key, and the receiver decrypts that by using public key. If receiver do not have my private key, he can only see that th emessage is from me. And he can verify it easily on the bitcoin database.

  2. What 2 use-cases can public key cryptography be used for?
    It is used to send and receive bitcoin.
    Also I saw somebody was trying to proove that he owns some big amounts of blocks of bitcoin, so he put his public key to his message, hoping to add some weight to that. I saw Ivan was laughting on him,…

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#1262

A public key is derived from your private key which is a very large number that is randomly selected by your computer.

Public Keys are used for creating Encryption, as well as for creating a digital signature that is signed to a message to authenticate you as the real sender, upon receipt by the recipient over a public network, where the recipient can cross reference your message with your public key, to validate that you truly sent the message.

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#1263

Homework on Public and Private Keys - Questions

  1. Describe the concept of public and private key with your own words.
    The private key is a unique alphanumeric code generated by the computer to represent the address where the funds/data is stored. It is used as a signature stamp verifying that the data/funds to be sent to another address is from this originating address. Anyone with this code will be able to confirm any transactions originating from this address. Also, the private key is needed to decrypt the data coming into the address that it represents.
    A public key is a hashed value derived from the private key representing the same address. The alphanumeric code generated is the one given to others to indicate the destination for which the funds/data they are sending to you is to be received. In addition, the public key is used to encrypt the data sent by the originator/sender. This code does not give permission to access the data/funds stored at the actual address.

  2. What 2 use-cases can public key cryptography be used for?
    Public key cryptography can be used for encrypting data before it leaves the originating address. It is also used to specify where to send the data without revealing or providing access to content of data in receiving address.

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#1264

Hi there!! We say that the public key is generated from the private key, so it’s not random. For the private key, we can use random data.

#1265

Hi there!! Also, you can get the public key from the private key, but no the other way around!

#1266
  1. If you want to send a encrypted message to someone on a public and insecure network you would need a private key to generate a public key to encrypt the message. Then to decrypt that message you can only do so using the private key used to generate that public key.

They’re just numbers but because of the hash functions it’s impossible to generate the private key from the public key.

  1. One use case is to encrypt messages while the second use case is for digital signature. This is the reason why Bitcoin uses Pri/Pub keys to sign a transaction
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#1267

Hi guys :wink: I feel a bit confused following the video at min 10:30 where Ivan says that the signature derives from the private key (sign the message with the private key) then from the other side Bob can check the signature using Alice public key and, with some calculation, compare the signature to the public key to confirm that the Alice sent the message (looking at private keys).

I don’t understand how’s possible if I can’t reproduce the private key using the public and also the private key shouldn’t be public for security reason.

Thanks in advance for any answer :slight_smile:

#1268

1. Describe the concept of public and private key with your own words.
It is like a box with a lock that can be only be locked by me (I’m the only one that has the private key) and be open by who has the opening key (the public key). Of course is a special lock that cannot be opened by a lock picker. Otherwise you can read the famous Alice and Bob story…

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

  • Encryption of messages (Encrypt with a public key and only the owner of the relative private key can read it)
  • Digital signatures (sign your message with your private key generating a digital signature so that the receiver can prove with your public key that it was you that sent it)
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#1269

Public and Private Keys

  1. Describe the concept of public and private keys with your own words.
    Public key and private keys have been around for decades. Public and private keys are helpful in encrypting messages, making them protected and secretive. Without the encryption, prying eyes will be able to view the messages on a unsecured network. Private keys, which generates a public key, is a one way function. There is no way to go the other direction, to generate the private key, from the public key.

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

  1. Encryption: When sending an encrypted message, one can take the others public key to encrypt the message. To open the message, the private key or the receiver needs to be used to decrypt the message.
  2. Digital signatures: Another feature of public and private key cryptography, are digital signatures which are mainly used in the crypto space. Digital signatures are signatures that are attached to a message or in Bitcoin terms, a transaction, which identifies a specific persons private key, in order to prove that person actually did send a transaction to someone else. Public keys are the keys that are shared and broadcasted for others to see. A private key is what is kept private, which protects your information.
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#1270

Answer above in quote

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