平均因子分解法，適用于正定矩陣First, let s recall the definition of the Cholesky decomposition: Given a symmetric positive definite square matrix X, the Cholesky decomposition of X is the factorization X=U U, where U is the square ROOT matrix of X, and satisfies:
(1) U U = X
(2) U is upper triangular (that is, it has all zeros below the diagonal).
It seems that the assumption of positive definiteness is necessary. Actually, it is "positive definite" which guarantees the existence of such kind of decomposition.
可在系統(tǒng)引導(dǎo)時(shí)工作的ROOTKit,較簡(jiǎn)單
1) It s very small.The basic framework is just about 100 lines of assembly code.It supports 2000,XP,2003
2) It patches the kernel at runtime(no files are patched on disk).(basic version has this code removed , so as others could understand it easily).
3) BOOT KIT is PXE-compatible.
4) It can even lead to first ever PXE virus
5)It also enables you to load other ROOT kits if you have physical access(Normally ROOT kits can only be loaded by the administrator)
