Masking support in FIELDPROCs

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FIELDPROCs were originally designed to transparently encode or decode data. Several third party products use the support to provide transparent column level encryption. For example, to allow a credit card number or social security number to be transparently encrypted on disk.

The FIELDPROC support has been extended to allow masking to occur to that same column data (typically based on what user is accessing the data). For example, only users that have a need to see the actual credit card number will see the value while other users may just see masked data. For example, XXXX XXXX XXXX 1234.

The new support is enabled by:

1. Allowing the FIELDPROC program to detect masked data on an update or write operation and returning that indication to the database manager. The database manager will then ignore the update of that specific column value on an update operation and will replace it with the default value on a write.
2. A new parameter is also passed to the FIELDPROC program. For field procedures that mask data, the parameter indicates whether the caller is a system function that requires that the data be decoded without masking. For example, in some cases, RGZPFM and ALTER TABLE may need to copy data. If the field procedure ignores this parameter and masks data when these operations are performed, the column data will be lost. Hence, it is critical that a field procedure that masks data properly handle this parameter.

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