Comparison of three typical encryption algorithms of DES and AES and RSA

Comparison of Des and AES

Since the DES algorithm has been revealed to the world, the academic circles have carried on the research and the intense controversy about its security and so on. Technically, the criticism of DES is mainly focused on the following aspects:

1, as a block cipher, DES encryption units have only 64-bit binary, which is too small for data transmission, because each packet contains only 8 characters, and some of these bits also use for odd pages parity or other communication overhead.

2, DES key bits are too short, only 56 bits, and the key used in each iteration is recursive, this correlation will inevitably reduce the security of the cryptographic system, in the existing technology with the poor lifting method to find the key has become feasible.

3. DES cannot resist differential and linear cryptanalysis.

4, the DES user actually uses the key length is 56bit, theoretically the maximum encryption strength is 256. The DES algorithm increases the encryption strength (for example, by increasing the key length), and the system overhead increases exponentially. In addition to improving the hardware function and increasing the parallel processing function, the DES algorithm's encryption strength can not be improved from the algorithm itself and software technology.

Compared with DES algorithm, the AES algorithm solves the above problems, and it is mainly manifested in the following aspects:

1, the operation speed, in the feedback mode, no feedback mode of hardware and software, Rijndael have shown very good performance.

2, the demand for memory is very low, suitable for the restricted environment.

3, Rijndael is a packet iteration password, packet length and key length design flexibility.

4, the AES standard supports variable packet length, the packet length can be set to any multiple of 32 bits, the minimum value is 128 bits, the maximum value is 256 bits.

5, the key length of AES is larger than DES, it can also be set to any multiple of 32 bits, the minimum value is

6, 12 bits, the maximum value is 256 bit, so it is impossible to use the poor lifting method is not possible to crack.

7, the design strategy of AES algorithm is WTS. The WTS is presented for differential analysis and linear analysis, and can be used against differential cryptanalysis and linear cryptanalysis.

Comparison of Des and RSA

The key of RSA algorithm is very long, it has good security, but the computation of encryption is very large, and the encryption speed is slow to limit its application range. In order to reduce the amount of computation, when transmitting information, traditional encryption method is used in combination with public key encryption method, that is, the information is encrypted with improved des conversation key, then the key and information digest are encrypted using RSA key. When the other party receives the message, it decrypts it with a different key and can check the information digest.

Using DES and RSA combination of applications, so that their advantages and disadvantages are complementary, that is, DES encryption speed, suitable for encrypting longer messages, can be used to encrypt plaintext; RSA encryption is slow, security is good, applied to des key encryption, can solve the problem of DES Key distribution.

At present, this method of RSA and Des Combination has become the standard of email secure communication.

The following are the links of the three algorithms in their respective examples:

The simplest DES encryption algorithm realizes the way of RSA encryption and decryption by AES simple encryption and decryption method

Comparison of three typical encryption algorithms of DES and AES and RSA