Characteristics and application considerations of--AES algorithms for cryptographic chips

AES is a block Encryption standard algorithm, it is proposed to upgrade the replacement of the original DES encryption algorithm. Therefore, its security strength is higher than des algorithm. However, it should not be understood that the security of the system and data is not only related to the application encryption algorithm, but also to the encryption application scheme. Like des algorithm, AES is also a symmetric encryption algorithm, and the storage and protection of the key directly determines the security of the whole system.

AES is the most common 3 scenarios, respectively, AES-128, AES-192 and AES-256, the difference is the key length is different, AES-128 key length is 16bytes (128BIT/8), the latter are 24bytes and 32bytes respectively. The longer the key, the higher the security intensity, but with the increase of the number of operation wheels, the computational overhead will be greater, so the user should make a reasonable choice according to different application situations.

In the application process, in addition to focus on the key length, you should also pay attention to confirm the algorithm mode. AES algorithm has five kinds of encryption mode, namely CBC, ECB, CTR, OCF, CFB, the latter three modes are more complicated and less application, do not elaborate, only the ECB and CBC mode are introduced.

The full name of the ECB model is electronic Codebook book, the code-based model. The pattern is to divide the entire plaintext into groupings of the same length, then encrypt each group and stitch the encryption results to the final result, C = c1c2c3 ... Cn. It is basically consistent with the DES algorithm encryption process in ECB mode.

The full name of the CBC mode is cipher Block Chaining, which first divides the plaintext into several groupings of the same length (as in the ECB mode), where the initial vector IV is used to generate the C1 with the first set of data XOR or after the encryption operation. The C1 is generated C2 as the initial vector and the second set of data, and then after the encryption operation. And so on, when the last set of data encryption is complete, the encryption results are stitched into the final result, C = c1c2c3 ... Cn.

In conclusion, the AES192 algorithm is similar to DES algorithm, which is block encryption algorithm, and the ciphertext data exists independently in 16 bytes. If the length of the plaintext is 16 bytes, when the first 16 bytes of the plaintext are changed, only the first 16 bytes of the ciphertext are affected, and the 16 bytes are unchanged after the ciphertext. Therefore, in the application of AES algorithm to the transmission line data encryption process, if you want to ensure that the overall change of ciphertext, to ensure that each block of plaintext data is changed.

I hope this article can let you have a more intuitive understanding of AES algorithm features, more secure and efficient use of AES algorithm design data encryption and decryption scheme, the LKT of the AES algorithm interface efficient use.