text: is there any such crack-proof software?   yes. it is software that has never been released and never will be.  the effects of security exploitation can be lessened by, for example, not using any secure data. that doesn't mean there will be no bugs. ideally, no code would contain bugs. but we are talking about software - ideals are real.  the bugs are not in the software, they are in the programmer.   note to answerers below me: http://secunia.com/product/100/ <- vulnerabilities effecting openbsd.  this is about programs, not encryption. if a program is encrypted, that does not mean the program has no security vulnerabilities that can be exploited ("cracked"), it just means that it's encrypted. additionally, just because it may be much harder to brute force a doubly encrypted message does not mean it is impossible (and there are other methods for breaking encryption).