Digital Security

at the Border

09/27/2025

Exp 03/01/2026

Agenda

• Welcome & Intro

• Digitalsecurity at the US Border

• 10 min break

• Signal Workshop

Who are we? Who are you?

We are …

    The Cypurr Collective

Beginner-friendly cybersecurity events with a holistic approach. Teaching to build community self-defense

We DO NOT tolerate language or behavior meant to demean or harm folks based on their identity

Security is scary, let’s be gentle.

Step up; Step Back

Privacy:

• We’re in public! Keep it general.

• Stories Stay. Lessons Leave.

• Journalists, Researchers, etc make yourselves known!

Safer space workshop

Freedom of the Press Foundation's

Davis Erin Anderson

Handout:  https://tinyurl.com/0927-bordertraining

(directs to https://drive.google.com/file/d/13XX3Tk4f0i8fnhOjXJUnKGrmpHfEo0JP/view?usp=sharing)

Guest Speaker

10m Stretch

cypurr.org

slides.com/cypurr/signal-workshop

Upping your

Settings

Signal

09/27/2025

Exp 10/01/2026

Why Signal?

Signal offers private "end to end encrypted" texts, calls and video between users

• Tested
  • security audits and subpoena history
• Open Source
  • no secrets in how it works
• 501c3 non-profit
  • prevents "enshitification"
• Free
  • No subscriptions and no ads.

The downsides?

• People you contact might not use it!
  • Called "Network effect"
• One choice
  • Unlike texting and other "protocols", no app variety.
• Requires a phone number for setup
  • Not anonymous
  • But settings help!
• Storage encrypted by phone
  • unlocked phone = unlocked messages
  • But settings help!

What's e2ee?

• Encryption is the use of a math formula to makes data unreadable, unless you have secret information called a "key"

• For data in transit there are two "ends", origin and destination.

• Many middle steps and 3rd parties

Unencrypted "plaintext"

images via ssd.eff.org

What's e2ee?

"Transport layer" encryption

• Now very common to have encryption between you and the host (like Facebook or Instagram)

• Better, but at the whim of these hosts

• Sometimes falsely called "end to end"

What's e2ee?

End to End Encryption

• Information only available on the ends

• Data at rest still needs to be managed

• Metadata can still be observerd

What makes Signal Unique?

• "Signal Protocol" changes keys frequently

  • If one message is cracked, future and past messages are not

  • Adopted by WhatsApp (Meta), Google's RCS, Skype (MS)

• Unlike others, Signal encrypts metadata. Only knows

      1. Phone number

      2. Account Creation time

      3. Time Last Seen

1. Search "Signal" on app store
2. Install the app
3. Contact Permission

https://ssd.eff.org/module/how-to-use-signal#download-and-install-signal

4. Register your number

• Receive code over text

5. PIN and Profile

• Order depends on Android/iOS
• PIN is for info on Signal Servers, like settings and profile
• Profile is visible to "everybody" by default, and always to people you contact.

https://ssd.eff.org/module/how-to-use-signal#download-and-install-signal

Signal is installed!

• Verifies no tampering in your connection
• Open a chat with the contact → tap their name → "view safety numbers"

https://ssd.eff.org/module/how-to-use-signal#download-and-install-signal

• Verifies no tampering in your connection
• Open a chat with the contact → tap their name → "view safety numbers"

Compare

Or

Tap QR to scan

Tap your profile (iOS then tap "Settings")

Set name under "@username"

• No need to share phone number
• Subpoena protection

https://ssd.eff.org/module/how-to-use-signal#download-and-install-signal

Tap your profile (iOS then tap "Settings")

Under "Privacy"

• Hide Phone # (under "Phone Number")
• Disappearing Messages

https://ssd.eff.org/module/how-to-use-signal#download-and-install-signal

Tap your profile (iOS then tap "Settings")

Registration Lock (under "Account")

• Requires PIN to register number to a new device

Notifications

https://ssd.eff.org/module/how-to-use-signal#download-and-install-signal

• Changing phone numbers
• Screen lock
• Hide in app switcher
• Disable link previews
• Keyboard data
• Signal Proxy
• Hide IP when calling

https://ssd.eff.org/module/how-to-use-signal#download-and-install-signal

Thanks!

Thanks to the Freedom of the Press Foundation

(https://freedom.press/donate/)

More resources at ssd.eff.org

Find us on cypurr.org

Ask about our email list