Abstract: A searching method determines, given a specified encryption method (or set of encryption methods) and a specified pattern (or set of patterns), whether a given text contains an encryption, with any key, of anything fitting the pattern or patterns. The procedure detects and locates patterns that are present within data that has been encrypted, provided that the encryption method is one of a variety of simple methods that are often employed by computer programs such as computer viruses. The method includes:1. applying an invariance transformation to the chosen pattern (or set of patterns) to be matched, to obtain a "reduced pattern";2. applying the same reduction to the encrypted data to obtain "reduced data";3. using standard string searching techniques to detect the existence of a match between the reduced pattern and the reduced data, thereby signalling the likely existence of the pattern in encrypted form within the encrypted data;4.

Abstract: A method includes the following component steps, or some functional subset of these steps: (A) periodic monitoring of a data processing system (10) for anomalous behavior that may indicate the presence of an undesirable software entity such as a computer virus, worm, or Trojan Horse; (B) automatic scanning for occurrences of known types of undesirable software entities and taking remedial action if they are discovered; (C) deploying decoy programs to capture samples of unknown types of computer viruses; (D) identifying machine code portions of the captured samples which are unlikely to vary from one instance of the virus to another; (E) extracting an identifying signature from the executable code portion and adding the signature to a signature database; (F) informing neighboring data processing systems on a network of an occurrence of the undesirable software entity; and (G) generating a distress signal, if appropriate, so as to call upon an expert to resolve difficult cases.