Integrity verification of pseudonymized documents

A method of verifying the integrity of a set of pseudonymized subdocuments, wherein each subdocument is a portion of a first document that is to be converted into a pseudonymizable document, said method using a first set of random values corresponding to at least a subset of the leaves of a binary tree generated based on a seed value, a second set of values each generated based on a combination of at least one value from the first set of values and at least one subdocument from the redacted document, a set of pseudonyms each corresponding to a subdocument, and an integrity certificate generated based on a verifiable document from which the pseudonymized document originated, said method comprising, with a processor of a computer system:

• generating a third set of values, based on the first set of random values, wherein each subdocument corresponds to at least one value of the third set of values;
• generating a fourth set of values based on:
• (a) a subdocument and a corresponding value from the third set of values;
• (b) the second set of values;
• and (c) at least one pseudonym of the pseudonym set, for each subdocument in the pseudonymized document;
• generating a summary value based on the generated fourth set of values;
• and
• generating a signal based on a result of applying a verification process to the generated summary value and the integrity certificate.

A system for generating a pseudonymizable document, said system comprising a computer system comprising a processor, said system further comprising:

• a value generator arranged to generate:
• (a) a first value set comprising at least one of random and pseudo-random values each corresponding to at least one subdocument, wherein each subdocument is a portion of a first document that is to be converted into said pseudonymizable document and (b) a pseudonym set comprising a pseudonym corresponding to at least one subdocument in the first document;
• a commitment generator communicatively coupled with the value generator and arranged to generate:
• (a) a second value set wherein each value of the second value set is based on applying a commitment scheme to a subdocument of the document and a value of the first random value set corresponding to the subdocument and (b) a third value set wherein each value of the third value set is based on applying a hash function to a value of the second value set and a pseudonym corresponding to the subdocument;
• and
• an authenticator value generator communicatively coupled with the commitment generator and arranged to generate a summary value based on the third value set.