Is Signal Messenger more private than other messengers using the Signal protocol?

Below is a brief conversation I had with Perplexity AI about the privacy of Internet messengers that use the Signal protocol for encrypting their messages (Facebook Messenger, Google Messages, Skype, Whatsapp etc), versus Signal Messenger itself.

Are other messenger apps using the Signal protocol as private as Signal Messenger?

I understand that many messengers have adopted the open-source protocol developed by Signal, for encrypting their own messages and calls.

Do any of these apps using the Signal protocol approach the same level of security as Signal Messenger, or are these apps still designed in a way that metadata and other information is less privately managed than with Signal’s own app – Signal Messenger?

Answer from Perplexity AI

Apps that adopt the Signal Protocol for encrypting messages and calls do benefit from its strong end-to-end encryption, but they generally do not match Signal Messenger’s overall level of privacy, particularly regarding metadata management.

Signal Messenger’s security advantages:

Signal uses the Signal Protocol to encrypt messages and calls end-to-end, ensuring only sender and recipient can read or hear the content.

• It implements “Sealed Sender” technology, which hides who is sending a message from Signal’s own servers, significantly reducing metadata exposure (such as who is communicating with whom).
• Signal collects minimal metadata, making it difficult for third parties to track communication patterns or user relationships.
• Group metadata (membership, titles) is also protected from the server, and features like disappearing messages enhance privacy.
• Signal’s entire client and server design are built around minimizing data collection and protecting user privacy beyond just encrypting message content.

Other apps using the Signal Protocol:

• WhatsApp and Facebook Messenger have integrated the Signal Protocol for end-to-end encryption of messages and calls, but these apps do not implement the same level of metadata protection as Signal Messenger itself.
• For example, WhatsApp collects more metadata (e.g., contact lists, usage patterns) and its parent company Meta has different privacy policies and infrastructure, which can expose more user information despite encrypted content.
• Other apps like Wire and Line use custom implementations of the Signal Protocol but may differ in metadata handling and overall privacy architecture.
• Many apps implement the Signal Protocol only for encryption but do not replicate Signal’s server-side privacy features like Sealed Sender, so metadata may be more accessible to their servers or third parties.

Summary

While the Signal Protocol provides strong cryptographic guarantees for message content, the overall privacy and metadata protection depend heavily on the app’s design and server infrastructure. Signal Messenger remains unique in combining the Signal Protocol with advanced metadata protection techniques and minimal data retention policies. Other apps using the Signal Protocol typically do not achieve the same level of comprehensive privacy, especially in terms of metadata management.

Thus, apps using the Signal Protocol approach Signal Messenger’s encryption strength but generally fall short of its holistic privacy protections.

Is Signal Messenger’s superior privacy due to technology advantages or design decisions?

Is it fair to say that the merits of Signal Messenger as a private messaging tool come less from its technology advantages than from design decisions focused on privacy. Other companies can freely use Signal’s encryption protocol, but choose to design their messengers in such a way as to not guarantee the same level of privacy to their customers, particularly regarding metadata.

Answer from Perplexity AI

Yes, it is fair to say that Signal Messenger’s merits as a private messaging tool stem less from unique encryption technology—since the Signal Protocol it developed is open source and widely adopted—and more from its comprehensive design decisions focused on privacy, especially metadata protection.

While many other companies freely use the Signal Protocol to secure message content end-to-end, they often do not replicate Signal’s rigorous approach to minimizing data collection and safeguarding metadata. Signal’s architecture is explicitly designed to avoid storing sensitive user information such as contacts, social graphs, group memberships, profile names, and message metadata on its servers.  Features like “sealed sender” further obscure who is messaging whom, limiting metadata exposure even to Signal itself.

In contrast, other messaging apps that use the Signal Protocol typically implement only the encryption layer and maintain more extensive metadata for their own purposes, such as contact discovery or user profiling. This results in less privacy overall, despite encrypted message content.

Signal’s open-source nature and nonprofit funding model also reinforce its singular focus on privacy without commercial incentives to collect or monetize user data.

Summary

Signal’s privacy advantages arise from its holistic design choices—minimizing metadata retention, protecting social graphs, and offering privacy-preserving features—beyond just the cryptographic strength of the Signal Protocol. Other apps may match its encryption but not its comprehensive privacy guarantees, especially regarding metadata management.