Patent ID: 7512232

Claim:
A computer-readable medium having computer-executable instructions that, when executed by a computer, performs a method for protecting digital media comprising: obtaining a message M having two portions, wherein M 1 is one of the portions of the M and M 2 is another; generating one or more codes having a combination with M 2 implicitly embedded therein, wherein calculations that generate the one or more codes do not employ M 2 , and M 2 cannot be derived from these calculations of one or more codes, the generating further comprising: finding a value of a variable per-message key (k) where a predefined mathematical function, M 2 =H 0 (M 1 , g k ), employing M 1 and g k produces a result equivalent to M 2 , wherein g is a fixed element of order q in a fixed group, and H 0 is a predefined hash function instantiated by using a keyed version of a secure hash function; when such a value of k is found, calculating the two or more codes, where one code is r and another is s, with r being calculated using another predefined mathematical function employing M 1 and g k , r=H 1 (M 1 , g k ), and with s being calculated using still another predefined mathematical function employing M 1 and g k and r, s=k/(r+1)âˆ’x H 2 (M 1 , g k )mod q; and reporting the one or more codes, by which reporting the one or more codes facilitates a cryptographic technique for protecting digital media.