As one of the important technologies for ensuring information security, asymmetric encryption plays a key role in various fields such as network communication and e-commerce. This article will take you deep into the understanding of asymmetric encryption.
Public Key Cryptography
In public key cryptography, the keys are divided into two types: the encryption key and the decryption key. The sender encrypts the message using the encryption key, while the receiver decrypts the ciphertext using the decryption key, thus exhibiting the characteristic of asymmetry. In public key cryptography, the encryption key is generally public. Because the encryption key can be shared openly, it is called the public key. The public key can be directly sent to the receiver via email. In contrast, the decryption key must never be disclosed; it can only be used by the owner, hence it is called the private key.
The Process of Public Key Communication
Below is an example of communication between Alice and Bob, illustrating the process of asymmetric algorithm communication:
1. Key Generation: First, Bob generates a pair of keys, namely the public key and the private key. The private key is securely kept by Bob, while the public key is made public, such as being published on a secure server or directly provided to Alice. 2. Encryption Process: When Alice wants to send a message to Bob, she retrieves Bob's public key from a public source. Alice then uses Bob's public key to encrypt the message she wants to send, generating the ciphertext. This ciphertext can only be decrypted with Bob's private key. 3. Transmitting the Ciphertext: Alice transmits the encrypted ciphertext to Bob through the internet or other means. During transmission, even if the ciphertext is intercepted by a third party, it cannot be cracked to retrieve the original message because the third party does not possess Bob's private key. 4. Decryption Process: After receiving the ciphertext, Bob uses his private key to decrypt it, thereby obtaining the original message sent by Alice.Through this process, Alice and Bob achieve secure communication, ensuring the confidentiality of the information during transmission.
RSA
RSA is the most widely used public key cryptographic algorithm, named after the initials of its three developers. RSA can be used for public key cryptography and digital signatures. In RSA, plaintext, keys, and ciphertext are all represented as numbers.
RSA Encryption
Assuming the sender wants to send a message to the receiver (which is an integer less than), the receiver has already generated the public key and the private key.
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Encryption Calculation: The sender uses the receiver’s public key to encrypt the message, calculating the ciphertext.
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Transmitting the Ciphertext: The sender sends the ciphertext to the receiver through the internet or other channels.
RSA Decryption
After receiving the ciphertext, the receiver uses their private key to decrypt it.
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Decryption Calculation: The calculation is performed.
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Obtaining the Plaintext: Through the above calculation, the receiver can obtain the original message.