Personal computer system and methods for proving dates in digital data files

A method of maintaining a digital data file in a personal computer, comprising:

• providing a trusted time source in the personal computer, wherein said trusted time source provides a certifiable time for an unalterable time stamp, wherein said certifiable time confirms at least one of said digital data file's access, creation, modification, receipt, or transmission;
• receiving a request to save said digital data file from a user;
• saving said digital data file at a moment in time;
• retrieving from said trusted time source a date and a time corresponding to said moment in time, wherein said moment in time is substantially a current time of said trusted time source corresponding to receipt of said request;
• appending said date and said time retrieved from said trusted time source to said digital data file;
• signing said digital data file with said date and said time retrieved from said trusted time source appended thereto;
• hashing said digital data file to produce a digest;
• signing said digest with a key to produce a certificate;
• appending said certificate to said digital data file;
• saving said file with said certificate appended thereto;
• and
• verifying trust in the content of said digital data file with said certificate appended thereto.

A method of maintaining trust in content of a first digital data file and content of a second digital data file in a personal computer, comprising:

• providing a trusted time source in the personal computer, wherein said trusted time source provides a certifiable time for an unalterable time stamp, wherein said certifiable time confirms at least one of said first digital data file's access, creation, modification, receipt, or transmission;
• receiving a request to save said first digital data file from a user;
• saving said first digital data file at a first moment in time;
• retrieving from said trusted time source a date and a time corresponding to said first moment in time, wherein said moment in time is substantially a current time of said trusted time source corresponding to receipt of said request;
• appending said date and said time retrieved from said trusted time source to said first digital data file;
• signing said first digital data file with said date and said time retrieved from said trusted time source appended thereto;
• hashing said first digital data file to produce a first digest;
• signing said first digest with a first key to produce a first certificate;
• appending said first certificate to said first digital data file;
• saving said first digital data file with said first certificate appended thereto;
• verifying trust in the content of said first digital data file with said certificate appended thereto;
• and
• appending said first digital data file, with said first certificate appended thereto, to said second digital data file.