Alias, Season 3

Jack:
Sloane gave you a key, which he claims was sent to him some time before you woke up in Hong Kong.

Sydney:
Yeah, his claim was pretty convincing: it was written in my handwriting.

...

Jack:
Remember when I told you that during the time you were missing, I contacted your mother? That cipher text was encoded using a method that she devised.

Sydney:
What does this mean? That I was in contact with Mom during the two years I was gone?