Learn EDB: Basic Encryption

LewisC’s An Expert’s Guide To Oracle Technology

An ITToolbox user recently asked a question on the EnterpriseDB discussion group, Oracle equilant UTL_I18N.STRING_TO_RAW IN ENTERPRISEDB.

Basically, Sreenivas asked which functions in EnterpriseDB could be used to implement dbms_crypto, hex_to_raw, string_to_raw, etc. I believe he is using EnterpriseDB Postgres Plus Advanced Server which is the product that gives Oracle Compatibility. The short answer to his question is that right now, there are no compatibility functions for those. The long answer is that you can re-implement that functionality using native PG functionality.

If you look at Sreenivas’s message you can see how his existing code works. I posted a simple example in response which I am reposting below. The PG docs suggest that you use PGP based encryption rather than what they call raw encryption. I think it depends on exactly what you’re doing, personally. Anyway, raw encryption was closer to what Sreenivas was doing so that was what I based my example on.

I’ve used DBMS_CRYPTO in Oracle quite a bit but this is my first use of encrypt/decrypt in PG. If you have any suggestions for improving it, I’d like to hear them.

Hi Sreenivas,

I saw your post on the edb forum but and planned to write a blog entry on this topic.

The thing is that there isn’t a one to one translation in EDB yet. The easiest thing is to rewrite your procedure and use built-ins that are available.

It is recommended that you use the PGP function in postgres as opposed to the raw encryption functions for better security. However, raw encryption more closely matches what you are trying to do. Below is an example of using raw encryption with AES.

You don’t need to convert to hex as you’ll be using bytea which is easily converted from and to a string. If you really need international support, check out the pg decode function (which is different from Oracle’s decode). http://www.postgresql.org/docs/current/static/funct ions-string.html

Here is a very simple example that you can use to build your procedure:

declare

  original_data text := 'I am going to be encrypted';
  data bytea;
  cipher bytea;
  crypto_type text;
  encrypted_data bytea;
  final_string text;

begin

  -- conversion to bytea, could use cast too
  data := original_data;

  --set cipher key
  cipher := 'not a strong key, use pgp instead';

  -- select type: aes or blowfish (bf)
  crypto_type := 'aes';

  -- encrypt the data
  select encrypt(data, cipher, crypto_type) into encrypted_data;

  dbms_output.put_line('Encrypted: ' || encrypted_data );

  -- decrypt the data 
  select decrypt(encrypted_data, cipher, crypto_type) into final_string;
  
  dbms_output.put_line('Decrypted: ' || final_string );

end;

Hope this helps,

LewisC


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