Submitted by: @pavel-zotov

Query-1:

Trivial:

with
a as (
select s_origin
from (
select 'Encrypts/decrypts data using symmetric cipher' as s_origin
from rdb$database
)
)
select
a.s_origin
from a
;

It issues obvious result:
S_ORIGIN Encrypts/decrypts data using symmetric cipher

Query-2:

The same as Query-1, but we add call to ENCRYPT() function, see line marked as "[ 1 ]" below:

with
a as (
select s_origin
from (
select 'Encrypts/decrypts data using symmetric cipher' as s_origin
from rdb$database
)
)
select
a.s_origin
,encrypt( a.s_origin using aes mode ofb key '0123456789012345' iv 'abcdefghhgfedcba') as s_encrypted ------------- [ 1 ]
from a
;

Result will be:
S_ORIGIN
456E6372797074732F64656372797074732064617461207573696E672073796D6D657472696320636970686572
S_ENCRYPTED
910805BDA8B05C475E8B5D3D0971D58649EA0D549FEA1633A8811429183E925E1C2C77CE4E3B9DCDFA0C75997E

So, content of the column 'S_ORIGIN' has been changed (and I could not find any way to 'materialize' CTE 'a' in such manner that content of S_ORIGIN will be preserved from changing).

Commits: d501922