Product Overview: Signal
Signal is an open-source, encrypted messaging service designed for secure and private communication. Developed by the non-profit Signal Foundation and its subsidiary Signal Messenger LLC, Signal offers a robust platform for instant messaging, voice calls, and video calls, ensuring end-to-end encryption for all communications.
Key Features
Secure Communication
- Signal uses end-to-end encryption for all forms of communication, including text messages, voice notes, images, videos, and files. This encryption is based on the Signal Protocol, which includes Perfect Forward Secrecy (PFS) to ensure the highest level of security and privacy.
Multi-Platform Support
- Signal is available on multiple platforms, including Android, iOS, Windows, macOS, and Linux. Users can register and use the app on their mobile devices and then extend its use to desktop clients.
Registration and Privacy
- Initially, Signal required users to register using their mobile telephone numbers, which allowed easy integration with the phone’s contact list. However, as of March 2024, Signal has introduced configurable usernames, enabling users to hide their phone numbers from other users if desired.
Messaging and Media
- Users can send a variety of content, including text messages, images, videos, GIFs, voice notes, contacts, and location information. The app also supports features like quoting specific messages, message reactions, one-time viewable media, and disappearing messages that can be set to delete after a specified time period (ranging from 5 seconds to one week).
Group Chats and Calls
- Signal supports group messaging with up to 1,000 members and group voice and video calls with up to 40 participants (previously limited to 8). Group chats include features like admin controls, mentions, and the ability to generate and share group invite links.
Additional Features
- Disappearing Messages: Users can set messages to automatically delete from both the sender’s and recipient’s devices after a specified time.
- Message Reactions: Users can react to messages with emojis.
- Screen Lock and Biometric Authentication: The app can be locked with the phone’s PIN, passphrase, or biometric authentication.
- Storage Management: A built-in tool helps users manage and free up storage space by sorting and deleting media and files.
- Customization: Users can change the app icon, customize chat colors and wallpapers, and adjust font sizes.
Voice and Video Calls
- Signal supports one-to-one and group voice and video calls over wired or wireless data connections. Users can switch cameras, microphones, or views during calls and even share their screens during desktop calls.
Payment and Cryptocurrency
- Signal includes a cryptocurrency wallet functionality, currently supporting MobileCoin for in-app payments in various regions.
Security and Verification
- The app includes mechanisms for users to verify the identity of their contacts through safety numbers or QR codes. It also employs a trust-on-first-use mechanism to notify users if a correspondent’s key changes.
Usability and Accessibility
- Signal’s interface is clean and user-friendly, with features like typing indicators and read receipts that can be enabled or disabled. The app also supports proxy connections for users in regions with restricted internet access.
Open Source and Transparency
- Signal’s software is entirely open-source, published under the AGPL-3.0-only license. The code is available on GitHub, and the service publishes transparency reports, ensuring minimal data logging and no logging of IP addresses.
In summary, Signal is a highly secure and feature-rich messaging app that prioritizes user privacy and security, making it a preferred choice for those seeking a reliable and private communication platform.