What Is the Advanced Encryption Standard?

The Advanced Encryption Standard (AES) in cryptography, also known as the Rijndael encryption method, is a block encryption standard adopted by the US federal government.

This standard is used to replace the original

Advanced encryption standard algorithms address worrying issues in many ways. In fact, those methods that attack data encryption standards have no effect on the advanced encryption standard algorithms themselves. If true 128-bit encryption or even 256-bit encryption is used, brute force attacks will take a long time to succeed.

Although the advanced encryption standard has its shortcomings, it is still a relatively new protocol. As a result, security researchers haven't had that much time to crack the encryption method. We may find out at any time that a new attack method will break this advanced encryption standard. At least this possibility exists in theory. ^[2]

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Strictly speaking, AES and Rijndael

By-pass attacks do not attack the password itself, but rather encryption systems that are implemented on insecure systems that inadvertently leak information.

In April 2005, DJ Bernstein published a cache timing attack method, which he used to crack a load

symmetry/

Counting mode (CTR mode) encryption is to encrypt a series of input data blocks (called counting) to generate a series of output blocks. The output blocks are XORed with the plaintext to get the ciphertext. For the last data block, it may be a local data block with a long u-bit. This u-bit will be used for XOR operation, and the remaining bu-bits will be discarded (b represents the block length). CTR decryption is similar. This series of counts must be different from each other. Suppose the counts are represented as T1, T2,, Tn. The CTR mode can be defined as follows:

The CTR encryption formula is as follows:

Cj = Pj XOR Ek (Tj)

C * n = P * n XOR MSBu (Ek (Tn)) j = 1, 2 n-1;

The CTR decryption formula is as follows:

Pj = Cj XOR Ek (Tj)

P * n = C * n XOR MSBu (Ek (Tn)) j = 1, 2 n-1;

The structure of the AES CTR mode is shown in Figure 5.

Figure 5 Pattern structure of AES CTR

Fig 5 Structure of AES CTRMode

Encryption method: The cryptographic algorithm generates a 16-byte pseudo-random code block stream. The pseudo-random code block is XORed with the input plaintext to produce ciphertext output. The ciphertext can be XORed with the same pseudo-random code to reproduce the plaintext.

CTR mode is widely used in ATM network security and IPSec applications. Compared with other modes, CTR mode has the following characteristics:

Hardware efficiency: Allows multiple blocks of plaintext / ciphertext to be processed simultaneously.

Software efficiency: Allows parallel computing and makes good use of parallel technologies such as CPU pipelines.

Preprocessing: The output of the algorithm and encryption box does not depend on the input of plaintext and ciphertext, so if there is sufficient memory to ensure security, the encryption algorithm will only be a series of XOR operations, which will greatly increase throughput.

Random access: The decryption of the ciphertext of the i-th block does not depend on the ciphertext of the i-1th block, providing high random access capability

Provable security: can prove that CTR is at least as secure as other models (CBC, CFB, OFB, ...)

Simplicity: Unlike other modes, the CTR mode only requires the implementation of encryption algorithms, but does not require the implementation of decryption algorithms. For essentially different algorithms such as AES, this simplification is huge.

No padding, which can be effectively used as streaming encryption.

Error does not propagate: Each bit in the ciphertext transmission is reversed by mistake, which only affects the decryption of the block in which the ciphertext is located. In CTR mode, after k + 1 self-synchronization, subsequent ciphertexts can be correct Decrypt. (K means block length 128)

Must be used with Message Authentication Code (MAC).

Integrity check cannot be performed: Loss of bits during cipher text transmission will cause subsequent bits to be decrypted incorrectly.