| 摘要 |
A method for securely encrypting or decrypting a message or for generating or verifying a digital signature in a message, in which the message is subjected, with the aid of a processor, to a mathematical operation using a key (k) which can be represented in the form of a binary number with a sequence of bits, and computational operations are sequentially carried out on auxiliary variables for each bit. The dependence of the computational result on the values of individual bits is taken into account by reading the memory addresses from the auxiliary variables and assigning them to address variables. The difference between the addresses is calculated and, depending on the respective current bit, is added to, or subtracted from, the computer addresses. The assignment of the auxiliary variables to the address variables can thus be interchanged. As a result, the order and selection of the computational operations is controlled on the basis of bits without the program sequence having to contain jump instructions. |
