According to records, in 400 BC, the ancient Greeks invented the permutation code. 188 1 year, the world's first telephone secrecy patent appeared. During the Second World War, the German military started the Enigma cipher machine, and cryptography played a very important role in the war.
With the development of information and digital society, people's awareness of the importance of information security and confidentiality is constantly improving, so in 1997, the American National Bureau of Standards announced its implementation.
With the promulgation of "American Data Encryption Standard (DES)", non-governmental forces began to fully participate in the research and application of cryptography, and the encryption algorithms adopted included DES, RSA, SHA and so on. With the increasing demand for encryption strength
High, recently appeared AES, ECC, etc.
Using encryption technology can achieve the following purposes:
Confidentiality: prevent the user's identity or data from being read.
Data integrity: prevent data from being changed.
Authentication: Ensure that the data comes from a specific party.
2. Introduction of encryption algorithm
According to the different types of keys, modern cryptography can be divided into two categories: symmetric encryption algorithm (secret key encryption) and asymmetric encryption algorithm (public key encryption).
Symmetric key encryption system uses the same key for encryption and decryption, and both parties must obtain this key and keep it secret.
The encryption key (public key) and decryption key (private key) used in asymmetric key encryption system are different.
Symmetric encryption algorithm
Symmetric encryption algorithm is used to encrypt sensitive data and other information. Commonly used algorithms include:
DES (Data Encryption Standard): A high-speed data encryption standard, which is suitable for encrypting a large amount of data.
3DES(Triple DES): Based on DES, a piece of data is encrypted three times with three different keys, which is more powerful.
AES (Advanced Encryption Standard): Advanced encryption standard, which is the next generation high-speed and high-security encryption algorithm standard;
Auger electron spectroscopy
In June 2000, NIST (National Institute of Standards and Technology) announced the adoption of a new key encryption standard selected from 65,438+05 candidate algorithms.
Rijndael was chosen as the future AES. Rijndael was founded by researchers Joan Damon and Vincent in the second half of 1999.
Rijmen created it. AES is increasingly becoming a practical standard for encrypting various forms of electronic data.
The American Institute of Standards and Technology (NIST) formulated a new advanced encryption standard (AES) specification on May 26th, 2002.
Algorithm principle
AES algorithm is based on permutation and permutation operation. Arrangement is to rearrange data, and replacement is to replace one data unit with another. AES uses several different methods to perform permutation and permutation operations.
AES is an iterative symmetric key block cipher, which can use 128, 192 and 256-bit keys, and 128-bit (16
Byte) block to encrypt and decrypt data. Unlike public key encryption using key pairs, symmetric key encryption uses the same key to encrypt and decrypt data. The number of bits of encrypted data returned by block cipher is the same as that of input data.
Same. Iterative encryption uses a circular structure in which input data is repeatedly permuted and replaced.
Comparison between AES and 3DES
Algorithm name
Algorithm type
Key length
speed
Decryption time (construction machine tries 255 keys per second)
resource consumption
Auger electron spectroscopy
Symmetric block cipher
128,192,256
high
14.9 trillion years
low
3DES
Symmetric feistel cipher
1 12 or 168.
low
4.6 billion years
middle
Asymmetric algorithm
Common asymmetric encryption algorithms are as follows:
RSA: Invented by RSA Company, it is a public key algorithm that supports variable-length keys, and the length of the file block to be encrypted is also variable.
DSA (Digital Signature Algorithm): Digital signature algorithm, which is a standard DSS (Digital Signature Standard);
ECC (Elliptic Curve Cryptography): Elliptic Curve Cryptography.
Eccentric wheel (short for eccentric)
1976, because symmetric encryption algorithm can no longer meet the needs, Diffie and Hellman published an article entitled "New Trends in Cryptography", which introduced the concept of public key encryption. RSA algorithm was proposed by Rivet, Shamir and Adelman.
With the progress and perfection of large integer decomposition method, the improvement of computer speed and the development of computer network, in order to ensure the security of data, RSA keys need to be continuously increased.
However, the increase of key length greatly reduces the speed of encryption and decryption, and the hardware implementation becomes more and more unbearable, which brings a heavy burden to the applications using RSA, so a new algorithm is needed.
Replace RSA.
In 1985, N.Koblitz and Miller proposed that elliptic curves should be applied to cryptographic algorithms based on the discrete logarithm problem ECDLP in point groups on elliptic curves over finite fields. ECDLP is a more difficult problem than factorization, and it is exponentially difficult.