  Date of birth (DOB) has historically been considered as private information
and safe to use for authentication, but recent years have seen a shift towards
wide public sharing. In this work we characterize how modern social media users
are approaching the sharing of birthday wishes publicly online. Over 45 days,
we collected over 2.8M tweets wishing happy birthday to 724K Twitter accounts.
For 50K accounts, their age was likely mentioned revealing their DOB, and 10%
were protected accounts. Our findings show that the majority of both public and
protected accounts seem to be accepting of their birthdays and DOB being
revealed online by their friends even when they do not have it listed on their
profiles. We further complemented our findings through a survey to measure
awareness of DOB disclosure issues and how people think about sharing different
types of birthday-related information. Our analysis shows that giving birthday
wishes to others online is considered a celebration and many users are quite
comfortable with it. This view matches the trend also seen in security where
the use of DOB in authentication process is no longer considered best practice.
