Portable data carrier provide with access protection by rendering messages unfamiliar
View Patent ↗The invention relates to a data storage medium having a semiconductor chip which has at least one memory in which an operating program is stored which contains a number of commands, with each command producing signals which can be detected from outside the semiconductor chip. According to the invention, the data storage medium is designed such that data which is used more than once for a calculation process is scrambled using different functions.
1. A data storage medium comprising a semiconductor chip which has at least one memory in which an operating program is stored which contains a number of commands, with each command producing signals which can be detected from outside the semiconductor chip, wherein the data storage medium is arranged to use different functions to scramble data which is used more than once for a calculation process for each use, wherein the calculation comprises an encryption process by means of modulo operations, in which a message M is used if there is a “1” in the exponent d, and the message M is varied using a different function for each use.
2. A data storage medium comprising a semiconductor chip which has at least one memory in which an operating program is stored which contains a number of commands, with each command producing signals which can be detected from outside the semiconductor chip, wherein the data storage medium is arranged to use different functions to scramble data which is used more than once for a calculation process for each use, wherein a factor r i *n is added to a message M for each use i (i=1 . . . k), where r is a random number and n is the modulus.
3. A data storage medium according to claim 2 , wherein r i is the same for all i.
4. A method for protection of secret data in data storage media having a semiconductor chip which has at least one memory in which an operating program is stored which contains a number of commands, with each command producing signals which can be detected from outside the semiconductor chip, comprising scrambling data which is used more than once for a calculation process using different functions, wherein the calculation comprises an encryption process by means of modulo operations, in which a message M is used if there is a “1” in the exponent d, and the message M is varied using a different function for each use.
5. A method for protection of secret data in data storage media having a semiconductor chip which has at least one memory in which an operating program is stored which contains a number of commands, with each command producing signals which can be detected from outside the semiconductor chip, comprising scrambling data which is used more than once for a calculation process using different functions, wherein a factor r i *n is added to a message M for each use i (i=1 . . . k), where r i is a random number and n is the modulus.
6. A method according to claim 5 , wherein r i is the same for all i.
7. A method for protection of secret data in data storage media having a semiconductor chip which has at least one memory in which an operating program is stored which contains a number of commands, with each command producing signals which can be detected from outside the semiconductor chip, comprising scrambling data which is used more than once for a calculation process using different functions, wherein security-critical computation operations f(z) which have a correlation between z and f(z) are split into computation operations g1(z) and (g2f (g1 (z)), so that g1 (z) and (g2f (g1 (z)) are not correlated with one another.