发明名称 |
AN APPARATUS FOR PERFORMING HASHING OPERATIONS USING GALOIS FIELD MULTIPLICATION |
摘要 |
The invention comprises a method and apparatus for performing a hashing operation on an N bit number under control of a prespecified N bit hashing constant which comprises performing N/K finite field partial multiplications of the object to be hashed by the hashing constant, utilizing K logic and combinatorial circuits all of which operate in parallel to completely evaluate the number in N/K operations. Another feature of the present invention is that the hashing constant loaded into the system may be changed at will with a resultant changing of the hashing characteristics to suit a particular class of objects to be hashed. This is done by a "select" operation. In the "select" operation, the hashing constant is sequentially loaded into said K logic and combinatorial circuits, each of which comprises a feedback shift register (FSR), said feedback shift registers being so configured that at the end of K operational sequences each of said feedback shift registers contains said hashing constant shifted and permuted in accordance with the particular feedback configuration of said register, a number of bits proportional to its location in the sequence of feedback shift registers, such that the hashing constant in the shift register FSRi will be shifted in a predetermined direction (i-1) N/K bit positions. Each of the operational sequences referred to above comprises a hashing sequence which includes N/K shifts of the feedback shift registers. |
申请公布号 |
DE3377389(D1) |
申请公布日期 |
1988.08.18 |
申请号 |
DE19833377389 |
申请日期 |
1983.11.24 |
申请人 |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
发明人 |
CARTER, JOHN LAWRENCE;MARKOWSKY, GEORGE;WEGMAN, MARK N. |
分类号 |
G06F17/30;(IPC1-7):G06F15/40 |
主分类号 |
G06F17/30 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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