数据加密外文翻译

数据加密外文翻译内容摘要：

G(X, Y, Z) H(X, Y, Z) I(X, Y, Z) In which: Xamp。 Y expresses according to the position and, X | Y expressed that according to the position or, not(X) expressed takes according to the position instead. xor expresses according to the position different or. in the function X, Y, Z are 32bit. defines the array which needs to use: The T(i), i value 164, T(i) was equal to that abs(sin(i)) 4294967296 time of integral part, i is a radian. After the supposition first three step processing data length is 32*16*Nbit The fifth step: Output: Obtains finally ABCD is the output result, altogether 128bit. A is the low position, D is a top digit. Third Key Use in HMAC the key being possible to be the random length (key which will be longer than B first by the H processing). But when the key length is smaller than the L situation is disappointing, because like this will reduce the function the working strength. The length is bigger than L the key is acceptable, but the extra length cannot remarkable enhance the function the working strength. (if a stochastic key were considered that is unreliable, then chooses a long key is unwise). The key must select (or use stochastically formidable based on stochastic seed39。 s pseudorandom production method), and wants the periodic renewal. (the present attack has not pointed out an effective replacement key39。 s frequency, because these attacks are not in fact feasible. However, the periodic renewal key is one latent defect basic security measure which copes with the function and the key exists, and may reduce divulges the harm which the key brings. ) Forth matters needing attention HMAC is may not revise the sound code according to the first floor hashing function to be possible to use this way to define. Especially it when uses the H function must rely on the predefinition initialization value IV (a definite value, by each iteration hashing function when initialization its pression function assigns). However, if you want, may revise the H function the sound code to support invariable initialization value Ivs. This idea is this: The pression function the intermediate result which (K XOR opad) and (K XOR ipad) produces in the B word length block data may when the key just produced in advance calculates well. Saves first these intermediate results, then when each time has the news needs to confirm produces the H function the initialization value IV. This method must distinguish the news which has preserved the H pression function regarding two B word length block data (K XOR opad) and (K XOR ipad) the application for each. When distinguishes the short data stream, preserves such information is important. What we must stress: Treats these intermediate results to treat the key to be the same likely, and wants same to carry on the security. The above choice realizes the result which the HMAC method is local carries out, to internal operational has not affected Fifth safe Here will explain that the message discrimination mechanism the security is decided by the hashing func。