| 摘要 |
Software contained in memory (50) is encrypted by means of an encryption routine EN1 to the encrypted form illustrated at (50A). A decryption routine DE1, corresponding with encryption routine EN1, is embedded at (70) in the memory (50B). A further encryption routine EN2 is then applied to the contents of memory (50B), to create a further encrypted form at (50C). A decryption routine DE2, corresponding with encryption routine EN2 is embedded in the memory (50D). Further encryption routines can be applied, one after another, with a decryption routine being embedded in the memory before the next encryption routine is applied. The result is an encrypted form of the original software, protected by several layers of encryption, each with an associated decryption routine which has itself been encrypted by subsequent encryption routines. |
