Common encryption algorithms

The common encryption algorithms can be divided into three kinds, symmetric encryption algorithm, asymmetric encryption algorithm and hash algorithm.
Symmetric encryption
Encrypt and decrypt encryption algorithms that use the same key. The advantages of symmetric encryption algorithms are the high speed of decryption and the difficulty of cracking when using long keys. Assuming that two users need to encrypt and then exchange data using a symmetric encryption method, the user needs at least 2 keys and is exchanged, and if there are N in the enterprise, the entire enterprise needs NX (n-1) keys, and the generation and distribution of the keys will become the nightmare of the Enterprise Information Department. The security of the symmetric encryption algorithm depends on the storage of the encryption key, but it is impossible for everyone in the enterprise to keep a secret, and they usually leak the key out-if a user uses a key that is obtained by the intruder, the intruder can read all the documents encrypted by the user key. If a single encryption key is shared across the enterprise, the confidentiality of the entire enterprise document will not be discussed.
common symmetric encryption algorithms are DES, 3DES, Blowfish, Idea, RC4, RC5, RC6, and AES
Asymmetric Encryption
Encrypt and decrypt encryption algorithms that use different keys, also known as Public private key encryption. Assuming that two users want to encrypt the exchange of data, the two sides exchange the public key, using the other side of the public key encryption, the other side can be decrypted with their own private key. If there are n users in an enterprise, the enterprise needs to generate N-pair keys and distribute n public keys. Because the public key can be exposed, the user simply takes care of their private key, so the distribution of the encryption key becomes very simple. Also, because each user's private key is unique, other users can verify that the source of the information is true, in addition to the sender's public key, and that the sender cannot deny that the message was sent. The disadvantage of asymmetric encryption is that the decryption speed is much slower than symmetric encryption, and in some extreme cases, it can be even 1000 times times slower than asymmetric encryption.
Common Asymmetric encryption algorithms are: RSA, ECC (for mobile devices), Diffie-hellman, El Gamal, DSA (for digital signatures)
Hash Algorithm
the special place of hash algorithm is that it is a one-way algorithm, the user can use the hash algorithm to generate a specific length of the unique hash value of the target information, but not through this hash value to regain the target information. Therefore, the hash algorithm is commonly used in non-reversible password storage, information integrity check and so on.
common hash algorithms are MD2, MD4, MD5, HAVAL, SHA
the effectiveness of cryptographic algorithms can usually be measured by the complexity of the algorithm itself, the length of the key (the longer the key is more secure), and the speed of encryption and decryption. In the above algorithm, in addition to the DES key length is not enough, the MD2 speed is gradually eliminated, other algorithms are still in the current encryption system products used.

Reproduced:

Http://www.cnblogs.com/MikeChen/archive/2011/04/22/2024574.html

Common encryption algorithms