seems that You did not care to try to understand the replies You got on the same query posted to the section ...
here is an excerpt from the relevant IBM manuals
Encrypting your data through DB2 built-in functions
DB2® provides built-in data encryption and decryption functions that you can use to encrypt sensitive data, such as credit card numbers and medical record numbers.
You can encrypt data at the column or value level. You must install the Integrated Cryptographic Service Facility to use the built-in functions for data encryption.
When you use data encryption, DB2 requires the correct password to retrieve the data in a decrypted format. If an incorrect password is provided, DB2 does not decrypt the data.
The ENCRYPT keyword encrypts data. The DECRYPT_BIT, DECRYPT_CHAR, and DECRYPT_DB keywords decrypt data. These functions work like other built-in functions. To use these functions on data, the column that holds the data must be properly defined.
Built-in encryption functions work for data that is stored within DB2 subsystem and is retrieved from within that same DB2 subsystem. The encryption functions do not work for data that is passed into and out of a DB2 subsystem. This task is handled by DRDA® data encryption, and it is separate from built-in data encryption functions.
Attention: DB2 cannot decrypt data without the encryption password, and DB2 does not store encryption passwords in an accessible format. If you forget the encryption password, you cannot decrypt the data, and the data might become unusable.
Defining columns for encrypted data
When data is encrypted, it is stored as a binary data string. Therefore, encrypted data should be stored in columns that are defined as VARCHAR FOR BIT DATA.
Defining column-level encryption
For column-level encryption, all encrypted values in a column are encrypted with the same password.
Defining value-level encryption
When you use value-level encryption, each value in a given column can be encrypted with a different password. You set the password for each value by using the ENCRYPT keyword with the password.
Using predicates for encrypted data
When data is encrypted, only = and <> predicates provide accurate results. Predicates such as >, <, and LIKE return inaccurate results for encrypted data.
Optimizing performance of encrypted data
Encryption typically degrades the performance of most SQL statements. Decryption requires extra processing, and encrypted data requires more space in DB2.
data encryption as I already said before is MUCH MORE than simple database function call