Public key Encryption

The following information is from Wikipedia.

Public key Encryption (English:public-key Cryptography, also known as public key encryption ), or asymmetric encryption (asymmetric cryptography), a cryptographic algorithm type, in which a pair of keys is required, one is a private key and the other is a public key. These two keys are mathematically related, and the information obtained by encrypting a user's key can only be decrypted with the user's decryption key. If one is known, it is not possible to calculate the other one. Therefore, if one of the two keys is exposed, it does not compromise the secret nature of the other. The public key is a public key, and the private key is not public.

The idea was first proposed by Rive Merk (Ralph c. Merkle) in 1974 [1], after 1976. Whitfield Diffie (Whitfield Diffie) and Martin Herman (Martin Hellman) Two scholars based on one-way function and one-way dark gate function, create a key for the two parties to send and receive the message.

If the encryption key is public, this is used for the client to upload the encrypted data to the private key owner, which is known as the public key encryption (narrowly defined). For example, internet banking customers send encrypted data to the account operations of the bank's website.

If the decryption key is public, the information that is encrypted with the private key can be decrypted with the public key for the client to verify that the data or file published by the party holding the private key is complete and accurate, and that the recipient is sure that the message comes from someone with a private key, which is called a digital signature , and the public key is a digital certificate. For example, the installation program downloaded from the Internet, usually with the digital signature of the program creator, proves that the program is indeed published by the author (company) and not by a third party and has not been tampered with (authentication/authentication).

Common public key cryptography algorithms are RSA, ElGamal, knapsack algorithm, Rabin (special case of RSA), public key cryptography in Deffee-Herman key exchange protocol, Elliptic curve encryption Algorithm (English: Elliptic Curve Cryptography, ECC). The most widely used RSA algorithm (by the inventor Rivest, Shmir, and Adleman initials) is the famous public key encryption algorithm, ElGamal is another commonly used asymmetric encryption algorithm.

Advantages

Compared with symmetric key encryption, the advantage is that no shared universal key is required, and the decrypted private key is not sent to any user. Even if the public key is intercepted on the internet, it cannot be decrypted if there is no private key that matches it, and the public key being intercepted is useless.

Process

Assume that two user A sends a message to B. The public key of B is C, and the corresponding private key (also belonging to B) is D, and the plaintext is X.

1. A the plaintext is encrypted with the public key to form ciphertext C (x), and then the ciphertext is transmitted;
2. b receives the ciphertext, decrypts the cipher with the private key D (c (x)), and obtains the plaintext X to be communicated.

b sends a message to a and vice versa.

Public Key Cryptography

In cryptography, Public key cryptography , referred to as public key cryptography, also known as asymmetric cryptography , is a cryptographic study using a pair of public and private keys, which corresponds to a key cipher that uses only one key. In general, we call public-key cryptography including public-key cryptography and digital signature algorithms. Some public key cryptography algorithms can easily be transformed into a digital signature algorithm (such as RSA), while others require significant changes.

Public key Encryption