數(shù)據(jù)加密外文翻譯-展示頁
2024-11-14 05:59本頁面
【正文】 sible to use the suitable hashing function. Moreover the hashing function displays in the software aspect is very good. And the sound code is public and general. 2. Maintain the hashing function original performance, but does not cause its degeneration. 3. Cause reasonably based on about first floor hashing function supposition message discrimination mechanism encryption strength analysis. 4. When discovers either needs the operating speed is quicker or the safer hashing function, may very easy realize the first floor hashing function replace. [Annotation]: When p book documents, MD5 and SHA1 are use the most widespread encryption to use the hashing function. Second HMAC algorithm principles HMAC algorithm definition: Expresses as follows with the formula: HMAC=H(key or opad ,H(key or ipad,text)) H(X, Y) expression carries on one kind of Hash operation to X + Y news. Representative Ipad is redundant B time single byte hexadecimal system system constant OX36。 key represents 64 bytes strings of character, is posed of the key, insufficient makes up 0。 Key length ≥L byte. When is bigger than B, passes through the Hash putation to form L byte Peru key (B is first in the Hash algorithm an iterative putation block data byte count。 MD5Init(amp。 MD5Update(amp。 MD5Final(tk, amp。 key = tk。} (2) On one step will produce the B word length39。 (3) Fills data stream text to the second step result string of character. (4) Affects with H in the data stream which third step produces. transfer hashing function (MD5, SHA1) (5) The B word length string of character which and opad first step produces does the or else. k_opad[i] ^= 0x5c。s putation speed, this abstract is difficulty with explains (1) the text fills The MD5 algorithm request carries on the packing to the random length text, the constitution N64 Byte news grouping, N is an integer. And each grouping padding data is divided 2 steps. First, the packing causes the data position length exactly for (N648) the Byte number, namely in text valid data replacement 1 0x1, other makes up 0x0 to satisfy the above request. Then, again on replacement 8 bytes (64) before text data length (packing, byte count). Thus, the data by the packing is 64Byte (512bit) integral multiple. Also divides 16 4 byte subgroupings. (2) initialization MD5 parameter The 4 4 byte shift quantity (A, B, C, D) use for to take the text abstract the starting value: A=0x01234567 B=0x89abcdef C=0xfedcba98 D=0x76543210 (3) algorithm The MD5 algorithm is to the news grouping in turn iterative algorithm. 1st time operates the starting value is ABCD, each iterative putation39。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. Af
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