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Symmetric encryption algorithm used for sensitive information such as the data is encrypted, the commonly used algorithm including:
1: DES (Data Encryption Standard) : Data Encryption Standard, faster, and is suitable for the Encryption of large amounts of Data,
2:3 DES (Triple DES) : is based on DES, on a piece of data with three different keys to encrypt three times, higher strength,
4: the AES (Advanced Encryption Standard) : Advanced Encryption Standard, is the next generation Standard of Encryption algorithm, fast speed, high level of security,
Symmetric encryption algorithm is characteristic of open, small amount of calculation, fast encryption and encryption of high efficiency,
Deficiency is:
1: transaction both sides use the same key, security is not guaranteed, moreover,
2: every time for every user using symmetric encryption algorithm, you need to use the only other people don't know the key, it will lead to both receiving the number of keys have geometric progression growth, key management become the user's burden,
3: work on symmetric encryption algorithm in the distributed network system is difficult, mainly because of key management difficult
4: use the high cost, and compared with the public key encryption algorithm, symmetry encryption algorithm is able to provide encryption and authentication, lacks the function of signature, made using range is narrow,
In computer private network system widely used symmetrical encryption algorithm DES and IDEA, advocated by the national bureau of standards (AES is as a new standard to replace DES,
Symmetric encryption algorithm, the advantages of high speed encryption and hard to break when using long key, assuming that the two users need to use symmetric encryption methods to encrypt and exchange data, the user needs to be at least 2 keys and exchange of use, if there are n enterprise users, is the enterprise needs 2 n * (n - 1) key, key generation and distribution will become enterprise information department's nightmare,
Disadvantages: low security: the security of symmetric encryption algorithm depends on the situation of the preservation of the encryption key, but it requires the enterprise each those who hold the key to keep a secret is not possible, they will usually have intention to not intentional of take the key leaking out - if a user and the key was obtained by the invaders, an intruder can read the user key encrypt all the documents, if the enterprise Shared an encryption key, and the confidentiality of the whole enterprise document was impossible, DESCryptoServiceProvider
So what are common encryption algorithm?
1. DESDES algorithm called the Data Encryption Standard, that is, Data Encryption algorithm, DES Encryption algorithm is IBM research success and published in 1975, the entry of the DES algorithm has three parameters: Key, Data, Mode, in which the Key is 8 bytes a total of 64, is the job of the DES algorithm is the Key; Data for 64, 8 bytes are to be encrypted or decrypted Data,
3 des
2.3 DES (Triple DES) is a Triple data encryption algorithm (TDEA) password is known, it is so for each data block application three times DES encryption algorithm, due to the increasing ability of the computer operation, the original DES password key length easier by brute force; By adding 3 DES DES key lengths to avoid similar attacks, rather than designing a new block cipher algorithm,
3. AES
AES: also called Rijndael encryption method, is the U.S. federal government adopted a block encryption standard, used to replace the original DES, at present has become one of symmetric key encryption algorithm,
4. RC2
RC2 by cryptographers Ron Rivest design a kind of traditional symmetric grouping encryption algorithm, it can be used as the DES algorithm suggested alternative algorithm, its input and output is 64 bits, the length of the key variable from 1 byte to 128 bytes,
5. RC4
RC4 encryption algorithm is a famous RSA key trio of Ronald Rivest in 1987 designed the key length variable flow encryption algorithm clusters, as a result of the RC4 core part S - box length can be arbitrary, the speed of the algorithm can reach about 10 times of DES encryption, and has a very high level of nonlinear,
6. RC5
RC5 block cipher algorithm is 1994 by the Massachusetts institute of technology in Ronald l. Rivest invented by professor, and from the analysis of RSA, it is a block cipher algorithm of variable parameters, three variable parameters is: packet size, size and encryption key round number, the RC5 algorithm used in the three kinds of arithmetic: xor, and circulation,
Asymmetric encryption algorithm (asymmetric cryptographic algorithm), also known as "public key encryption algorithm, in this kind of cryptography method, need a pair of keys, one is a private key, the other is the public key, the key is related to mathematics, using the information obtained after a user key encryption can only use the user's decryption key can decrypt, if you know the one, can not calculate the other, so if one of a pair of keys, will not harm another secret nature, said public keys for the public; Unknown to the public key for the private key,
Asymmetric encryption algorithm needs two keys: public key (publickey) and a private key (privatekey), public key and private key is a pair of, if use public key to encrypt data, it is only with the corresponding private key can decrypt. If you use the private key to encrypt data, so it is only with the corresponding public key can decrypt, used for encryption and decryption are two different keys, so this kind of algorithm is called asymmetric encryption algorithm,
Asymmetric encryption algorithm to achieve the basic process of confidential information exchange is: party a to generate a pair of keys and will be one of the public as a public key to the other party; Get the party of the public key used to encrypt the key of the confidential information and then send to party a; Save yourself with another party a the private key to decrypt the encrypted information, on the other hand, party a can use party b's public key to the confidential information to sign and then send to party b; Party b to use its own private key to attestation of data,
The characteristics of asymmetric cryptosystem:
1: the complex algorithm strength
2: high safety: safety depends on the algorithm and the key but due to the complexity of the algorithm, and makes the encryption, decryption decryption speed without symmetric encryption speed, there is only one key in symmetric cryptosystem, and is open, if had to let each other know decryption key, so to ensure its security is to ensure that the key of safety, rather than the symmetric key system there are two keys, one of which is open, so that you can do not need to transfer each other like symmetric cryptographic keys, such security is big,
3: the confidentiality of the asymmetric encryption algorithm is better, it eliminates the need for the end user key exchange,
The working principle of
1. The sending of messages via A to B, A and B are to have A pair of public and private keys for encryption and decryption,
2. A private key secret, A public key to tell B; B the private key secret, public key told A, B
3. Send information when A to B, A with B's public key to encrypt the information, because A knows B's public key,
4. To send this message to B (B's public key to encrypt the message),
5. B after receiving the news, B with your own private key to decrypt the message, received all the other people cannot decrypt the message, because only B B's private key,
The main algorithm
RSA, Elgamal, knapsack algorithm, Rabin, d-h, ECC (elliptic curve encryption algorithm),
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