Casting varchar to bytea

Hi. Could someone please tell me how to convert a "varchar" to a "bytea" datatype.

I have a column which contains a number stored as a varchar. I have another column of type bytea. I'm trying to insert the value of the varchar column in the bytea column, but the conversion won't work.

Something like the following:

update webuser set ccnum = ccnumstring::bytea where userid=userid;

Any ideas how to do this?

Also, I have the PGCRYPTO module and I can't get the AES algorithm to decrypt properly. It will encrypt, but not decrypt. However, I can get the BLOWFISH algorithm to work in both directions. Can someone please give me an example of decrypting using the AES algorithm?

Thanks in advance.

Dylan