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    • 6. 发明授权
    • Polynomial hashing
    • 多项式散列
    • US4588985A
    • 1986-05-13
    • US567199
    • 1983-12-30
    • John L. CarterMark N. Wegman
    • John L. CarterMark N. Wegman
    • G06F12/08G06F17/30H03M7/00
    • G06F17/30949G06F12/0864
    • Elements x in a domain A are hashed into a range B by selecting any one of a plurality of hashing functions which collectively form an almost universal.sub.2 class of functions. The data element to be hashed is separated into individual sub-strings x.sub.1 through x.sub.n of no more than log.sub.2 (b) bits in length, where b is an integer, and the hashing algorithm is a polynomial of the form f.sub.y (x)=(y.sup.0 x.sub.1 +y.sup.1 x.sub.2 + . . . +y.sup.n-1 x.sub.n) (mod b). In general, for a finite field of b=p.sup.k elements, where k is a positive integer, there will be a hash function defined by the formula f.sub.y (x)=y.sup.0 x.sub.1 +y.sup.1 x.sub.2 + . . . +y.sup.n-1 x.sub.n, where the addition and multiplication operations are those defined by the finite field and y is an element of the field. In a second embodiment, the hashing is a two-stage process defined by g.sub.z (f.sub.y (x)), where f.sub.y (x) is defined as above and g.sub.z is a function selected from a known universal.sub.2 class of hash functions.
    • 域A中的元素x通过选择共同形成几乎通用的2类功能的多个散列函数中的任何一个来散列到范围B中。 要散列的数据元素被分成长度不大于log2(b)位的各个子串x1到xn,其中b是整数,并且散列算法是fy(x)=( y0x1 + y1x2 + ...。+ yn-1xn)(mod b)。 通常,对于b = pk元素的有限域,其中k是正整数,将存在由公式fy(x)= y0x1 + y1x2 +定义的散列函数。 的。 的。 + yn-1xn,其中加法和乘法运算是由有限域定义的,y是场的元素。 在第二实施例中,散列是由gz(fy(x))定义的两阶段过程,其中fy(x)如上定义,并且gz是从已知的通用2类哈希函数中选择的函数。