Software or other information integrity verification using variable block length and selection

A computer enabled method of verifying the integrity of a file having an associated verification file, the method comprising the acts of:

• providing the file from storage;
• reading a first entry of the verification file, the entry including a start address of a first portion of the file in the storage, the length of the first portion, and a checksum or hash value of the first portion;
• for the first portion, computing a checksum or hash value using a predetermined function;
• comparing the computed checksum or hash value with that of the first entry;
• and
• verifying the file integrity only if the checksums or hash values match.

Apparatus for providing the integrity of a file, comprising:

• storage for the file;
• a portion selector logic coupled to the storage;
• a portion length selector;
• a portion buffer coupled to the storage and to the selector logic for storing a portion of the file, wherein the length of the stored portion varies from portion to portion;
• a checksum or hash value calculator coupled to the portion buffer and which calculates a checksum or hash value of the portion in the buffer;
• an entry buffer coupled to the calculator and to the portion length selector and to the portion selector logic and which stores a start address of the portion in the storage, a length of the portion, and the computed checksum or hash value;
• and
• a verification storage coupled to the entry buffer and which stores for an entry for each of a plurality of portions of the file.

Apparatus for verifying integrity of a file, comprising:

• a file storage and an associated verification file storage;
• an entry buffer coupled to the verification file storage, which holds from the verification file storage an entry for a portion of a file in the file storage, the entry including a start address of the portion, a length of the portion, and a checksum or hash value;
• a portion selector coupled to the entry buffer and which selects from the file storage the portion associated with the entry held in the entry buffer;
• a portion buffer coupled to the file storage and the portion selector and which holds the selected portion;
• a checksum or hash value calculator coupled to the portion buffer and which computes a checksum or hash value of the selected portion;
• and
• a comparator coupled to the entry buffer and the calculator, and which compares the checksum or hash values to verify the integrity of the file only if the values match.