Problems with (Importing) Encrypted Data After Character Set Change Using Other NLS_CHARACTERSET Database or Upgrading the (client) Oracle Version
Last updated on DECEMBER 05, 2016
Applies to:Oracle Database - Enterprise Edition - Version 10.1.0.2 and later
Oracle Database - Standard Edition - Version 10.1.0.2 and later
Information in this document applies to any platform.
There is encrypted data stored in a CHAR, VARCHAR2, LONG or CLOB datatype in your database and after
* or changing the NLS_CHARACTERSET using alter database/Csalter or the DMU tool
* or using export/import into a new database that uses a different NLS_CHARACTERSET
* or moving the data using dblinks into a new database that uses a different NLS_CHARACTERSET
* or upgrading the database to a newer version
* or using a newer client side connection method (start using or upgrading ODBC, JDBC etc)
Your encrypted data is "corrupted" or in other words the values stored in the new database do not match the values stored in the new database.
So the encrypted data is not recognised any more by the application - typically this is used to store user passwords (not related to actual database users) for an application and the application will not allow (some) users to login any more after one of above changes.
All below is actually also valid when using CHAR, VARCHAR2 , LONG or CLOB columns to store other binary data like PDF , doc, docx, jpeg, png , etc files.
It's mainly to avoid someone poking around in (copies of) the data files on OS level, any user who has permissions to decrypt the data sees the data unencrypted.
If you have a table that is encrypted with TDE but, when using a user who has permissions to decrypt the data, you see ORA-29275 for some rows the problem is NOT with TDE but with the data itself. TDE is one layer "lower".
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