Hash function maps arbitrary length input message for fixed length output value, and the fixed length output value is called the input message’s hash value. The definition of the hash function can be expressed as: is a set of bits that represent arbitrary length; is a set of bit strings that represent the length of n. In order to ensure the safety of the hash function, hash length n should be at least 256 bit. Usually there is the key in operation; the hash function is divided into two parts: hash function with key and hash function without key [7] . It is shows as follows.

The SM3 hash function compresses any message no more than 2⁶⁴-1 bits into a 256-bit hash value. The algorithm first pads any given message into n 512-bit message blocks. The hash function consists of the following two parts: the message expansion and the state update transformation.

Message Expansion: The message expansion of SM3 splits the 512-bit message blocks M into 16 words, and expands them into 68 expanded message words and 64 expanded message words as follows:

State Update Transformation: The state update transformation starts from an initial value (A₀, B₀, C₀, D₀, E₀, F₀, G₀, H₀) = IV of eight 32-bit words and updates them in 64 steps. In step the 32-bit words and are used to update the state variables A_i, B_i, C_i, D_i, E_i, F_i, G_i, H_i as follows:

where

The bitwise Boolean functions and are defined as follows.

If M is the last block, then

is the hash value. Otherwise it is part of the input of the next message block.

Dynamic password, also known as a one-time password, which is a one-time e form of a password that changes by time, for user new password is created every time [10] [11] . In a certain time interval, a password can only be used once; repeated use of the same password will be rejected. The main idea of dynamic password is to add some uncertain factors in the process, such as the use of time, frequency of use or random numbers, and these changing factors acts as a dynamic factor of password. The basic goal is to improve the safety of password. Dynamic password technology has many advantages: randomness, dynamic, one-time. The current paper proposed SH3 based algorithm for dynamic password authentication generation based on time [12] . The dynamic password authentication scheme is time saver and used for dynamic token holding, keep synchronization based on time may be considered as dynamic token of the uncertain factors, the mutual authentication using same responsible for the algorithm to generate a consistent user login password. Only legitimate users can hold the token, the token time refreshed after 60 seconds, and creates new token after 60 seconds.

In addition, the time certification system and dynamic password authentication technology is based on, challenge/response mechanism of dynamic password authentication technology and the password sequence of dynamic password authentication technology. This certification system can therefore be explained as follows:

The basic idea of the technology authentication word dynamic password is, to create variable counter value as an uncertain factor and it has no relation with the principle of system time [13] . Therefore, the problem of time synchronization and certification has less communication between the two sides. Challenge and response of dynamic password identity authentication technology are based on the basic idea that the system certification randomly generates a number of challenges to the user. The users generate dynamic password according to the random number and their authentication information.

Proposed method has no strict synchronization requirements, so it can fundamentally avoid the problem of loss of step. But it needs to verify the operational steps, only one-way communication; several typical one-time password authentication mechanism [14] based on the time mechanism is relatively simple, and the client computation is small and has no special hardware requirements, and the anti-attack ability is strong.

The generation of dynamic password [15] is determined by three things; the sequence number “SN”, the key and time “T”. Sequence number “SN” and key are fixed but time “T” is changed in minutes, so the three factors constitute the text “M” as a variable, that is, the encrypted text is dynamic, so that it can prevent the attack [16] . At this point one-way hash function of the encryption algorithm, first encrypt the plaintext block. Our proposed SM3 algorithm is based on encryption algorithm for the state password, the plaintext string processing length is 256 bits (32 bytes, which accounted for 6 of T bytes of SN 6 bytes of key, 20 bytes). The design obviates the calculation steps of grouping plaintext, realize simple and feasible encryption algorithm.

The serial number “SN”, key and time “T” are connected to get the plain text string “M”. Time accurate to minutes, the format is “yyyymmddhhmm”. For example, t is assumed that the current time is 14:41 in February 27, 2012, that is, T = 201202271441, SN = 555888, key = 1122333344556677889900555888112233445566.

That is, M = 555888 778899001122334455 667788990020120022 144144556677889- 9001122. The overall goal of the above process is to get the initial password, so that it is difficult to guess.

It needs to convert 64-bit hexadecimal number to 6-bitdecimal number to produce the output hash value using SH3 Algorithm [17] .

The truncated dynamic password algorithm based on time and the implementation flow in Figure 1:

1) User ID, key, and time T after SM3 algorithm generates the hexadecimal array M [64];

2) Take T minute position t, m = t mod 10, remove the M [t], M [t + 10], M [t + 20], M [t + 30], M [t + 40], M [t +50] composition OTP [5] (hex);

3) The OTP [6] is converted to decimal, and combined into a decimal OTP’;

4) result 1 = OTP’ mod, is the final dynamic password generated by the dynamic password token based on SM3 algorithm.

For example, if the current time is 14:53, t = 53 mod 10 = 3 and this time recorded

for T [3] , plaintext encrypted, the output value M = debe9ff9 2275b8a1 38604889 c18e5a4d 6fdb70e5 387e5765 293dcba3 9c0c5732,to M [3] = f9, M [13] = 8e, M [23] = 65, order groups into OTP = f98e65, converted to decimal OTP’ = 16354917 and eventually generated dynamic password P = 16354917 mod = 354917. This method ensures the second dynamic of the password, which makes it impossible for the illegal users to obtain the key by guessing, and further improve the security of the dynamic password algorithm.

Dynamic password authentication method is based on challenge/response and time synchronization mode and acts as dynamic authentication method, it has dynamic factor: challenge/response, generate random number by triggering event (such as login) produced Challenge code; it is a way to change the time synchronization time. When challenge/response user for login authentication system generates a random number-the challenge code is sent to the user. The code received by the user in an encryption algorithm which is mixed with the users own password and a random number is sent subsequently to the server, authentication system can authenticate users with the appropriate method for checking.

A time synchronization authentication method is the elapsed time of a factor of change, after hashing we make comparison between the current values of time together with the seed key. Time synchronization is actually a way of parallel computing authentication methods; regular time factor is utilized instead of the random challenge code, thereby reducing the authenticator with the inter-working certified party, simple, easy to use and so on. However, the boundaries of time synchronization authentication method for time synchronization and time accuracy are higher; In order to meet the requirements of time synchronization, time synchronization mode password over time is constant, the delay suffered or replay attacks, and since the time factor is a regular change, increasing the probability of attacks; achieving time synchronization server the challenge is more complex than the response server, usually combined with adaptive calibration mechanism (such as a server implementation of some design time window automatically adjust the design); the reliability of authentication is not as challenge- response type authentication method, the jumping point critical time will have a blind spot. In summary, the dynamic password authentication system improves the authentication mechanism and provides more security against threats; provide more emphasis on safety and reliability and use the challenge-response based authentication methodology [18] .

Challenge/Response authentication can be implemented in two modes; encryption/de- cryption mode and parallel computation mode. Encryption/decryption mode authentication can be divided into public key system which is based on symmetric key system. On the other hand, randomized user authentication uses its private or shared symmetric key of the authentication server (AS) emitted RN encrypted challenge code, Then the encrypted authentication result respond back to the server, using the corresponding public key or shared symmetric key to decrypt the response code, as a result if same RN is generated then the user authentication is successful. In the encryption/decryption of authentication mode, the speed is relatively slow due to the complete encryption/decryption process. Especially for asymmetric keys; the most important thing is, even if the user is using a 128-bit symmetric key, although the number of bits encrypted output will vary depending on different algorithms, but at the end the length of the packet is a symmetric key, that is 32 hexadecimal digits, For accurate user input it is a challenging and complicated thing. The encryption/decryption mode of authentication is not mainly in the hardware token applications [19] . Parallel computing requires token authentication operation mode, the authenticator and the authenticator use the same factors separately according to a certain algorithm (hash encryption) operation, and then compares each other. Although it is based on parallel computing methodology of hash algorithm for its easy to use system resources and needs to oppose to 1/decryption less computing speed into the mainstream embedded system design approach, but it is not based on the full implementation of the digital signature manner, in law, it does not have auditable significance. The system is based on DSA [20] [21] (Digital Signature Algorithm) as authentication, is a total non-factor-based authentication method are inherently non-repudiation, and the system has been incorporated undeniable factor time-stamp, which implement a strong auditable login authentication system. Meanwhile, the implementation of the system to take half the software effectively solves the speed problem that DSA brought [22] .

Input information: “AA”, it’s ASCII code is “616263”, after filling the message shows in Table 1.

As show in the table, arbitrarily length information will be filled into affixed length information.

When after extending, W0, W1 … W67 are as follow Table 2.

The filled message after extending is show in Table 2. The table reflects that the message is messy. Same as above, W0’, W1’ … W63’ are as follow Table 3.

After 64 rounds of iterative form 256 bit hash values are as follows.

66c7f0f4 62eeedd9 d1f2d46b dc10e4e2 4167c487 5cf2f7a2 297da02b 8f4b8e0

According to local time, 2016, 4, 24, 14:54:25, get the initial value of dynamic password OTP = 62e229, convert it into decimal OTP’ = 6480937, finally get the truncated dynamic password P = 048093.