1/ The concept of private and public keys is cryptography terminology where public keys can be generated from a private key, but private keys cannot be determined from the public key. This makes it possible to have private and secure interactions on the internet.
2/ Data encryption and Digital Signatures
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- Describe the concept of public and private key with your own words.
As an entity, you can create a private key on a computer which is a long random number. It is almost impossible for the same number to be generated for two different private keys. The private key must be kept very safe and secure by the individual. From this private key, a public key can be generated using a mathematical calculation, this is a one way function. You cannot derive the private key from the public key. The public key can be displayed for anyone to use. Things can be sent to you, encrypted with your public key and then only you can decrypt it with your secure private key. Take great care of your private key. Lost of comproised private keys means you have no further access, or someone else does have access to anything linked with it, such as digital wallets etc.
- What 2 use-cases can public key cryptography be used for?
Encryption of a message, where the sender, uses the receivers public key to encrypt and make the message unreadable to others. The message can then be sent over public systems (such as public forums or through normal email system - across internet) to the receiver. The receiver can then unencrpyt the message using their private key.
Digital Signature. A message can be encrypted or not encrypted. What is important to know is that it came from the expected person, and not someone pretending to be them. The sender of the message signs the message using a mathematical calculation using their private key - it now has a digital signature. The message is then sent to the receiver. The receiver can see the public key of the sender and can tell that the digital signature was generated from the related private key druing a mathematical verification process.
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Public key are a shared data used to receive encrypted, signed or non-encrypted messages. It’s generated from private key. On the other hand, a private key is not shared or public, it remains just private and can be used to signed messages.
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So, it can be used for encryption and for digital signature.
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public and private keys are a way of sending encrypted messages to one another. The private key can be anything, it can be made-up. If I want to send encrypted messages I need a private and public key so I first randomly generate, or randomly make up a private key. I then run the private key through the algorithm and it generates my public key. I broadcast the public key. The person who wants to send me a mesage encrypts it with my public key. Anyone can download the message but it is encrypted, so it is nonsense gobldygook.
But I can decrypt it with my private key.
In blockchain transactions are like messages and decrypting transactions with my private key when i receive bitcoin is called “signing the transaction”
2 email and bitcoin
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Generating private and public keys is a way to protect and verify information. E. g., a private key is created by the originator of the message; a public key is created which is derived from the private key. The public key is accessible to anyone, but no one can figure out the private key via the public key. It’s a one-way process.
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Encryption and digital signatures.
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Signing a message is different than encryption. When you create a signature, it means you sign a message with your private key and others can verify it was you who signed it using your public key 
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1- Private key generate the public key trough an Hash and the private key can be used to decrypt a message .
2- The public key can be use to encrypt a message and to verify a digital signature
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1 - Computer generate random numbers, that results in a private key, than, you can generate a public key using some functions. Only the owner of private key can check the message
2 - Signature and Cryptography
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- the private key is a randomly generated code that exists out of a high amount of digits, your private key is the way you can sign messages/payments. you have to keep the private key for your own, without it you lose your wallet. you can get an public key out of your pvt key, the public key is for sharing to other people so they can communicate with you or send you payments.
- for paying with cryptocurrency and public key signing of digital documents
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1. Describe the concept of public and private key with your own words.
Private keys are kept secret (only holder should have it) while public keys are public-facing. A private key is a random string generated by a computer. A public key is then derived from this private key that you can share in order to perform transactions and encrypt messages. This is a one-way function, so you can derive a public key from a private key but cannot go backwards (getting a private key from a public key)
2. What 2 use-cases can public key cryptography be used for?
Encryption (sending private messages on an unsecured and open network) and digital signatures (the main use cases when it comes to cryptocurrency)
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A public key can be seen by everyone and is used by others to encrypt information. A private key is a very large number used to generate a public key, as well as being used to decrypt information someone sent you.
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Two use-cases: digital signatures and crypocurrencies.
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Computer generates a random number calls its Private key, and using that number as base generates a totally different number calls it Public Key. Public key its name refers to is for public access and private on the other hand should be kept private and protected. Both Private and public keys are unique at the same time public key can’t be used to find private key.
Public cryptography key can us used of Encryption and Digital signature.
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Ans.1) A public key is available for all to see and use on an open network. The public key enables encryption of any data submitted as an input. Therefore the private key which created that unique public key is the only key that can perform the decryption of that encrypted data. This concept is used to enable the safe secure transfer of confidential data via a public network such as the internet.
Ans.2) Public-key cryptography can be used in two ways. Cryptography is encryption and this is the first use case, encrypting and securing confidential data. The second use case is digital signatures which is the primary use case with cryptocurrency. For example, John wants to send some bitcoin to Mary. John locates or uses Mary’s unique public-key bitcoin address. This address (key) encrypts that bitcoin John wants to send, securing it for her, and furthermore directing it to her address. (Public key encryption can only be opened by the private key which created it - Mary’s private key) By sending this transaction, John automatically, and digitally signs that encrypted bitcoin amount with his unique private key, which is native to her unique public-key, thus verifying John as the unique sender. This solves the problem of privacy, authenticity, and transaction record cross-checks on the block-chain (…(a) does John have this bitcoin in the first place? if yes! (b) ok, now Mary has it - records are cross-referenced, validated & submit for consensus by the majority, verified & approved, updates are broadcast to the rest of the network), plus it enables secure transactions to be performed upon an open network. (internet)
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A private key is a random number generated by a computer and while a public key is generated using the private key you just generated. Everyone can generate a public and private key one of the most important things about these keys is you cannot find the private key using the public key, meaning you are the only person who knows the private key, you could call it a very secure password.
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Public key cryptography can be used to encrypt messages so you cannot be spied on by malicious people on the internet. You can also use Private/Public keys to generate a bitcoin address among other things.
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Hash functions are not used in the process of public key generation. For that we use the elliptic curve function
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This are both examples of digital signatures. You can also use them for encryption
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Bitcoin address is basically just a hash of the public key. Another use case which you use to send bitcoins is digital signatures
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- Public keys are generated from private keys (which is a random generated number). The public key can then be used to encrypt a message which ONLY the private key can decrypt.
- It can be used for message encryption and digital signatures
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Homework on Public and Private Keys - Questions
- Describe the concept of public and private key with your own words.
Answer: A one way system to secure the integrity and identity of a message. A very large random number held privately, used to create a public number (key)
- What 2 use-cases can public key cryptography be used for?
Answer: Signature and Identity
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A private key is a secret random number that is generated. This number is used to generate a public key using a hash function so that nobody can take the public key and reverse engineer the private key. This way someone can share a public key with everyone on the internet.
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the two use cases are Encryption, and Signatures. Encryption allows the use of securing a document or piece of information that only the owner of the private key can access and uncover it’s message. and a Signature allows the use of the private key to generate a unique “id” to essentially sign each message or document that proves it came from that specific owner of the private key.
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