The present invention provides a method for verifying an unreadable information-based indium that has been generated by a postal security device (PSD) for information-based indium comprising a 2-D bar code, certain human-readable information, a digital signature and a certificate. The method comprises the steps of attempting to read the 2-D bar code using sophisticated digital image processing when the 2-D bar code is not readable; and continuing normal processing when the 2-D bar code is readable with the sophisticated digital image processing. When the 2-D bar code is not readable two independent processes are used to determine the indicium certificate. A first process includes reading human readable information by optical character recognition using context, syntax, and redundancy in the human readable information to obtain a PSD-ID; and using the PSD-ID to look up in a certificate database a certificate corresponding to the information-based indicium. A second process includes interpreting partial bar code data and extracting a “best guess” of the certificate and searching the certificate database for the closest matching certificate. The method further comprises merging data obtained from the two processes and attempting to reconstruct bar code data from the merged data. If the merged data is sufficient, an attempt is made to verify the digital signature obtained from the merged data. If the signature is verified, normal processing is resumed. If the merged data is insufficient or if the signature is not verified, a suspect mailpiece record is created.