Security & PrivacyUpdated 17 October 2026
Passwords, hashing, verification and metadata
What makes a password strong, how hashing differs from encryption, how to verify a download, and what the metadata in your photos gives away.
Three operations get confused constantly, and the confusion is the source of most bad security decisions made by otherwise careful people. Hashing is one-way and proves a file has not changed. Encoding is reversible by anyone and protects nothing. Encryption is reversible with a key and provides confidentiality. These guides separate them properly, then apply the distinction: what makes a password strong (length, not punctuation), what a checksum does and does not prove about a download, and what a signature adds that a hash cannot. The privacy side is what your own files give away, starting with the EXIF data in a photo, which can include the exact place it was taken.
6 guides5 subjects
6 guides
Signing a PDF: what a signature image proves, and what it does not
Most documents people call "signed" contain a JPEG of a name. That is often fine, and it is worth knowing exactly what it is, because it proves almost nothing on its own.
Generating a random string that is actually random
Two generators produce strings that look equally random. One of them lets an attacker predict every future value after seeing a few.
What actually makes a password strong (it is not the special characters)
P@ssw0rd! satisfies every complexity rule ever written and is one of the first things any cracking tool tries. Here is what the maths actually says.
Hashing, encryption and encoding are three different things
If a system can email you your existing password, it is not hashing them. That single observation tells you a lot about how a service is built.
Verifying a download with a checksum: how, and what it actually proves
Checking a hash takes fifteen seconds and catches both a truncated download and a compromised mirror. It does not catch everything, here is the boundary.
What your photos reveal: EXIF metadata and how to remove it
A photo posted from home can contain the coordinates of the room it was taken in, accurate to a few metres, in a field nobody thinks to look at.