Patent ID: 7519830

Claim:
A method for detecting alteration of a first data value encrypted and stored in a memory, the method comprising: reading an encrypted data address from the memory, the data address being selected at random when the first data value was encrypted and stored in the memory; decrypting the encrypted data address; reading a second data value currently stored at the data address in the memory; reading an encrypted split value from the memory, the split value being a combination of a hash value of the first data value and a third data value that was stored at the data address in the memory when the first data value was encrypted and stored in the memory; decrypting the encrypted split value; combining the split value and the second data value to produce a recovered hash value; calculating a hash value of the first data value; comparing the recovered hash value to the calculated hash value of the first data value; and determining the first data value to be altered if the recovered hash value is not equal to the calculated hash value.