Table of Contents
- 1 What is the shared key of Alice and Bob?
- 2 Why can’t Bob choose 1 as the public key?
- 3 What is the shared secret key?
- 4 What is Bob’s public key?
- 5 What is M in RSA?
- 6 How does Bob verify Alice’s public key authenticity when Bob receives a message signed by Alice?
- 7 Why should Alice use Bob’s public key?
- 8 How would Alice decrypt Bob’s message?
Alice and Bob publicly agree to use a modulus p = 23 and base g = 5 (which is a primitive root modulo 23). Alice and Bob now share a secret (the number 18).
What key does Alice use to encrypt to Bob?
When Bob wants to send a message to Alice he uses his copy of her public key to encrypt the message. Alice uses her securely-stored private key to perform the decryption.
Why can’t Bob choose 1 as the public key?
1 is a bad choice because it makes very easy to reverse-engineer a key that will open Bob’s padlock, which is the opposite of what we want. This is a Python fragment which generates a RSA key with e = 1 . Now you have the private key!
What key would Bob use to verify the signature?
public key
Bob decrypts the document with Alice’s public key thereby verifying the signature.
A shared secret key is used by mutual agreement between a sender and receiver for encryption, decryption, and digital signature purposes. A shared secret key uses a text file that contains the key material for cryptographic operations.
Are used as the base of the public key infrastructure?
A public key infrastructure relies on digital signature technology, which uses public key cryptography. The basic idea is that the secret key of each entity is only known by that entity and is used for signing. This key is called the private key.
What is Bob’s public key?
The public key can be sent openly through the network while the private key is kept private by one of the communicating parties. The public and the private keys are cryptographic inverses of each other; what one key encrypts, the other key will decrypt. Bob encrypts the secret message to Alice using Alice’s public key.
When Alice sends a message to Bob encrypted via asymmetric encryption She uses?
Alice uses an asymmetric algorithm to encrypt a message with Bob’s public key and sends him the encrypted data, which he decrypts using the private key. Asymmetric algorithms include a “key generation” protocol that Bob uses to create his key pair, as shown by Figure 15-2.
What is M in RSA?
This is where number theory comes to the rescue in the form of the RSA crypto system. RSA stands for Rivest, Shamir and Adelman, who discovered the scheme in 1977.
What is meant by public key?
In cryptography, a public key is a large numerical value that is used to encrypt data. The key can be generated by a software program, but more often, it is provided by a trusted, designated authority and made available to everyone through a publicly accessible repository or directory.
How does Bob verify Alice’s public key authenticity when Bob receives a message signed by Alice?
Alice uses public key cryptography to create a digital signature. When Bob receives the message, he verifies the signature using Alice’s public key. If the signature is valid, then Alice has “signed” the message, and Bob can assume that Eve has not forged the message.
What is key and secret?
You need two separate keys, one that tells them who you are, and the other one that proves you are who you say you are. The “key” is your user ID, and the “secret” is your password. They just use the “key” and “secret” terms because that’s how they’ve implemented it.
Why should Alice use Bob’s public key?
She should use Bob’s public key to encrypt the message. Because Bob is the only one holding the private decryption key, he is also the only person that can decrypt the message. Bob wants to know for sure that the message he just received actually came from Alice. Alice keeps her encryption key private to encrypt the messages she sends.
How does a public key cryptosystem work?
In public key cryptosystems there are two keys, a public one used for encryption and and private one for decryption. 1 Alice and Bob agree on a public key cryptosystem. 2 Bob sends Alice his public key, or Alice gets it from a public database. 3 Alice encrypts her plaintext using Bob’s public key and sends it to Bob.
How would Alice decrypt Bob’s message?
To decrypt Bob’s message, Alice would, probably, have to meet the dancer at the Sheremetyevo airport, transport her to KGB, break the coin open and decrypt the message with the key identical to Bob’s. Phew! The operation involves a lot of people and resources.
How can Bob and Alice communicate securely in this scenario?
For Bob and Alice to communicate securely in this scenario, they first have to physically meet and establish the identical key, or, maybe, transfer the key. It’s not perfectly safe. Plus, if a smart MI-6 cryptographer detects suspicious activity and intercepts the ballerina, he might decipher the message.