IAX2 Encryption

Hello Guys

I am new to asterisk so my apologies if my question sounds too idiot

If I have these 3 lines in my iax.conf extensions will the conversation/media between these two accounts will be encrypted ? Or I need to do something extra to make it encrypted

[600]
type=friend
host=dynamic
username=600
**auth=md5**
secret=xxxxxx
trunk=no
notransfer=no
**encryption=aes128**
**encryption=yes**
context=test

[700]
type=friend
host=dynamic
username=700
**auth=md5**
secret=xxxxxx
trunk=no
notransfer=no
**encryption=aes128**
**encryption=yes**
context=test