Traditional Password Technology __ password

Password (cryptography) is a kind of information processing system, which involves many aspects such as confidentiality , integrality , authentication and non-repudiation . The History of cryptography development

Since the human society has the war, has the confidential communication, needs the information processing system. Before 1949, the research and application of cryptography was only a word conversion technique, which was referred to as cryptography. Since 1949, Shannon has done the related work, published "The Communication Theory of the secrecy system", has laid a solid theoretical foundation for the development of cryptography.

The development of cryptography is roughly divided into classical cipher period, modern password period and modern password period, among which, classical cipher period and modern cipher period become traditional password period. two leaps in cryptography and two milestone events in 1949 Shannon published the "Communication Theory of the secrecy system", which established the theoretical Foundation for the Cryptography system and became a science from cryptography. The first Leap 1976 years later, the United States Data Encryption Standard DES released, making cryptography research open and rapid development milestones in 1976, Diffe and Hellman published the new direction of cryptography, In this paper, a new concept of cryptography design is proposed, which has created an epoch of public-key cryptography. The second leap in 1978, Rivest, Shamire and Adleman first proposed the first practical RSA cryptosystem. Milestone Events Traditional Cryptography Technology

Although the technique, thought and analysis method of traditional cryptography system is very simple, it reflects the idea of cipher design and analysis, is the basic entrance of cryptography, and still has reference meaning for understanding, designing and analyzing modern cryptography. Replacement Password

Rearrange the plaintext according to certain rules in order to break the structural characteristics of the clear text. The replacement password is characterized by keeping all the characters of the plaintext unchanged, but using permutations to disrupt the position and order of the literal characters. Column Replacement Password

The encryption process is to first write out the plaintext in the set fixed packet width m by line, that is, every line has m characters. If the length of the clear text is not an integral multiple of M, the less-than-part is populated in the way agreed by both parties. The character matrix [MP]MXN [M_p]_{m\times N}] is obtained according to the position order of a permutation Σ\sigma interchange column in 1,2,⋯,m 1,2,\cdots,m. Then, the matrix is read out in sequence C by [MP]MXN [m_p]_{m \times n} According to the Order of column 1,2,⋯,m 1,2,\cdots,m.

For example, if the plaintext "Beijing 2008 Olympic Games" is encrypted, the matrix representing the plaintext is: m=⎡⎣⎢⎢⎢bglge2yai0mmj0pei8isnoc⎤⎦⎥⎥⎥m = \left[\begin{matrix} B & E &am P I & J & I & n \ G & 2 & 0 & 0 & 8 & O \ L & Y & M & P & I & C & \\g & A & M & E &s & \end{matrix} \right]

Its key can be expressed as (1,4,3,5,6) as a matrix: σ=⎡⎣⎢⎢⎢⎢⎢⎢0000101