An encryption-free technique for enabling the self-authentication of value documents
(including personal and commercial checks) presented at a point of purchase or
financial institution. Certain data contained on the value document may be signed
with a first digital signature and authenticated with a public key certificate
issued from a trusted certificate authority. The signed data and public key certificate
are stored on the value document, preferably in a two-dimensional bar code data
format. In the case of certain personal value documents (such as checks, credit
cards, passports, birth certificates, Social Security cards, etc.), a unique personal
identification number (PIN) also may be included in the document data that is signed
by a second digital signature. At a point of purchase, a merchant or teller can
scan and read the data stored in the two-dimensional bar code and other magnetically
recorded information, and together with the PIN the customer provides, can authenticate
the value document thus presented using the second digital signature. Alternatively,
if the customer is not present, if the personal value document contains the second
digital signature, the document may be verified using a PIN-generating algorithm
or other method that generates all permutations of PINs. The first digital signature
alone may be used to authenticate selected data within the personal value document
even when the PIN is not available. Similarly, in the case of a commercial value
documents, authentication of pre-printed data may be based entirely upon only the
first digital signature.