TDE: Format of Data in Datafiles (.dbf files) with NUMBER and VARCHAR2 datatype

Question

Nice to meet you all.

This is the first time I have posted here, so please feel free to let me know if I am wrong.

I am doing some research on the Transparent Data Encryption feature. I want to validate the ability to extract data without logging into the database instance and before encryption, by reading the .dbf file directly with HexEditor, Notepad++, or something equivalent.

The problem is with the data type VARCHAR2; the value is plaintext, the same as the returns when I query in the instance. But with NUMBER, DATE, or anything that is not VARCHAR2, I cannot find plaintext in the .dbf

Datatypes of columns

The returns when I query in the instance

Hex Editor returns plaintext with VARCHAR2 datatype data…

… but not with NUMBER datatype data

I did a lot of research on the Internet, but it seems there is no clear answer and no demo of the contents of data files before and after using TDE. Why is it like that? And more, I think that Oracle stores non-VARCHAR2 data types in binary format to save storage and VARCHAR2 data types for easily returning in query, am I correct?

Thank you for any guidance!

Vu Hoang.

Answer 1

SQL> select dump(200224, 1016) from dual;

DUMP(200224,1016)
-----------------------
Typ=2 Len=4: c3,15,3,19

SQL>

This section is right there on your screenshot in line 00327FE0 starting at column 07, this is how Oracle stores numbers.