To dream that someone is reading your diary, or to dream that your diary is stolen, indicates that you are keeping secrets. You have difficulties telling others how you really feel.
If you dream of reading someone else’s diary, you are mistrustful of others and you tend to poke your nose into other people’s business. Perhaps you have recently stumbled upon some information that was not meant for your eyes. [1]
If the diary is locked, then you have secrets that you don’t want anyone to know about.
If it is unlocked, then you feel like an open book.
If you are reading someone else’s diary, then you are prying where you don’t belong out of suspicion or fear.
A diary in a dream also may be a message for you to be mindful with whom you share your secrets.
A dream journal is seeing your life through the soul’s eyes or higher consciousness. [3]