# What Requirements Must A Public Key Cryptosystems Fulfill To Be A Secure Algorithm?

## What are the roles of the public and private key?

In Public key, two keys are used one key is used for encryption and another key is used for decryption.

One key (public key) is used for encrypt the plain text to convert it into cipher text and another key (private key) is used by receiver to decrypt the cipher text to read the message..

## How does Diffie Hellman key exchange achieve security?

The Diffie–Hellman key exchange method allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure channel. This key can then be used to encrypt subsequent communications using a symmetric key cipher. … It credits Hellman, Diffie, and Merkle as inventors.

## What is a one way function?

In computer science, a one-way function is a function that is easy to compute on every input, but hard to invert given the image of a random input.

## Which is the largest disadvantage of the symmetric encryption?

9. Which is the largest disadvantage of symmetric Encryption? Explanation: As there is only one key in the symmetrical encryption, this must be known by both sender and recipient and this key is sufficient to decrypt the secret message.

## What are the requirements of public key cryptography?

Public Key Cryptography Requirements Knowing the encryption algorithm and public key of the intended receiver, computation of cipher text must be easy. For a receiver of the message, it should be computationally easy to decrypt the obtained cipher text using his private key.

## What are the principles of public key cryptosystems?

Public Key CryptosystemPrinciples of Public-Key Cryptosystems. Evolved from an attempt to solve two of the most difficult problems associated with symmetric encryption. …  Each user generates a pair of keys to be used for the encryption and decryption  Each user places one of the two keys in a public register or other accessible file.More items…•

## Can public key be used to encrypt?

Data encrypted with the public key can only be decrypted with the private key, and data encrypted with the private key can only be decrypted with the public key. Public key encryption is also known as asymmetric encryption. It is widely used, especially for TLS/SSL, which makes HTTPS possible.

## How are public and private keys generated?

The public key is made available to anyone (often by means of a digital certificate). A sender encrypts data with the receiver’s public key; only the holder of the private key can decrypt this data. … In some cases keys are randomly generated using a random number generator (RNG) or pseudorandom number generator (PRNG).

## What are three broad categories of applications of public key cryptosystems?

What are the three broad categories of applications of public-key cryptosystems? Encryption/decryption: The sender encrypts a message with the recipient’s public key. Digital signature: The sender “signs” a message with its private key.

## What is a public key used for?

Public key cryptography allows someone to send their public key in an open, insecure channel. Having a friend’s public key allows you to encrypt messages to them. Your private key is used to decrypt messages encrypted to you.

## What are the properties of public key encryption?

Public-key cryptography, or asymmetric cryptography, is an encryption scheme that uses two mathematically related, but not identical, keys – a public key and a private key. Unlike symmetric key algorithms that rely on one key to both encrypt and decrypt, each key performs a unique function.

## What is RSA algorithm with example?

RSA algorithm is a popular exponentiation in a finite field over integers including prime numbers. The integers used by this method are sufficiently large making it difficult to solve. There are two sets of keys in this algorithm: private key and public key.