1, plain text:

Plain text refers to unencrypted text (or string) that ordinary people can understand, which belongs to cryptography terminology. In a communication system, it can be a bit stream, such as text, bitmap, digitized voice or digitized video image.

2. The key:

A key is a parameter entered in an algorithm for converting plaintext into ciphertext or ciphertext into plaintext. Keys are divided into symmetric keys and asymmetric keys.

3, ciphertext:

Ciphertext is encrypted text, and plaintext is encrypted text. The word encryption sometimes refers to ciphertext, but it is usually used to refer to encryption methods. The output of plain text after some disguise or transformation. It can also be understood as a set of characters or bits that cannot be directly understood. It is encrypted information that can be restored by an algorithm, not plain text.

Extended data:

The sender of information uses public key encryption, while the receiver of information uses private key decryption. The public key mechanism is flexible, but the speed of encryption and decryption is much slower than that of symmetric key encryption.

Therefore, in practical applications, people usually use them together. For example, a symmetric key encryption system is used to store a large amount of data information, while a public key encryption system is used to encrypt keys.

For ordinary symmetric encryption, the encryption operation and decryption operation use the same key. The commonly used symmetric encryption algorithm is simple and efficient, the key is short, and it is extremely difficult to decipher, because the security of the system mainly depends on the security of the key.

Therefore, it is a serious problem to transmit and save keys safely on the open computer network. Because both parties use the same key in symmetric cryptography, data signature and undeniable function cannot be realized.

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