Cryptography is an important secret means for communication parties to convert special information according to agreed rules. Cryptography is gradually developed in the practice of the struggle between encoding and decoding, and with the application of advanced science and technology, it has become a comprehensive frontier technology science. It is closely related to linguistics, mathematics, electronics, acoustics, information theory and computer science.
In Western European languages, kryptós (hiding) and gráphein (writing), which originated from Greek, are subjects that study how to transmit information in secret. In modern times, especially the mathematical research on information and its transmission is often regarded as a branch of mathematics and computer science, and it is also closely related to information theory. Ron Rivest, a famous cryptographer, explained: "Cryptography is about how to communicate in front of enemies." From the point of view of its own engineering, this is equivalent to the similarities and differences between cryptography and pure mathematics. Cryptography is the core of information security and other related issues, such as authentication and access control. The main purpose of cryptography is to hide the meaning of information, not its existence. Cryptography also promotes computer science, especially technologies used in computer and network security, such as access control and information confidentiality. Cryptography has been applied in daily life, including ATM chip cards, computer users' access passwords, e-commerce and so on.
The core of asymmetric encryption algorithm is that the encryption key is not equal to the decryption key, and no key can be derived from another key, which greatly strengthens the information protection, and it is easy to realize digital signature and electronic envelope based on the key pair principle.
The typical asymmetric encryption algorithm is RSA algorithm, whose mathematical principle is the decomposition of large prime numbers, and the keys appear in pairs, one is the public key and the other is the private key. The public key is public. You can use a private key to decrypt information encrypted by a public key, or you can use a public key to decrypt information encrypted by a private key.
For example, A sends information to B. Since B's public key is public, A encrypts the information with B's public key and sends it out. Because only B has the corresponding private key, the information can only be read by B. ..
A robust RSA algorithm requires its key length to be 1024 bits, and its weakness is the slow encryption and decryption speed.
Another typical asymmetric encryption algorithm is ECC algorithm, which is based on the mathematical principle of elliptic curve discrete logarithm system. The standard of this algorithm has not been determined in China, but only 192 bit is needed to realize solid encryption. So it should be better than RSA algorithm.
For encryption, there is basically no encryption algorithm that cannot be completely cracked, because as long as you have enough time, you can try it by exhaustive method. If an encryption algorithm is robust, it generally means that it will take a long time to exhaust under the existing computing conditions (such as 100 year).
RSA encryption algorithm is an asymmetric encryption algorithm. RSA is widely used in public key encryption standards and e-commerce. RSA was put forward by Ron Livingstone, adi shamir and Leonard Aderman in 1977. At that time, all three of them worked at MIT. RSA is a combination of the initials of their surnames.
1973, Clifford Cocks, a mathematician working in the British government communication headquarters, put forward the corresponding algorithm in an internal document, but his findings were classified as confidential until 1997.
Based on the decomposition of maximal integer, the reliability of RSA algorithm is very difficult. If someone finds a fast factorization algorithm, the information reliability of RSA encryption will definitely drop greatly. But the possibility of finding such an algorithm is very small. Nowadays, only short RSA keys can be cracked strongly. Until 2004, there was no reliable way to attack RSA algorithm in the world. As long as its key length is long enough, the information encrypted by RSA can't be cracked.
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