Expected behavior When i first sign up for DeltaChat or any other time, i can initiate mutuals discovery. This is when I allow DeltaChat to check my contacts if they are already in DeltaChat I will be told if my contact is finally in DeltaChat I know there is a security & privacy concern abo…

[image] irvan-putra: I know there is a security & privacy concern about this so I will refer to Bluesky trying their best to solve that concern by hashing the contact: hashing doesn’t solve the problem, it is not only about server storing phone numbers, but anyone being able to iterate over p…

I moved this comment to its separate issue: [image] Probe existing email contacts upon installation for easy onboarding Feature Proposal A user would install DC On first start, DC would scan for email addresses (along with fingerprints and public keys) in the device addres…

Probing email for all email address in address book not yet DeltaChat is actually different idea. This topic is actually to discover if someone else already in DeltaChat with both me and my contacts registering our intent to discover mutuals to a service and that service save our telltale like phon…

In that case, this is a duplicate of the following: [image] Contact-Lookup Service Feature Proposal Hello there, please forgive me if this has already been widely discussed but I didn’t see it anywhere: I’d like to propose a lookup server (or actually confirm…

Thanks, there is one that i miss, so i have replied there: [image] Search contacts by phone number Feature Proposal So i only know there is already this proposal even though i have created new one: Discover mutuals The cost is something to consider. It is possible if the…

Good catch. Note that if you write the link on its own line, a preview will be generated for it inline.

Thanks, that’s neat trick! If there is any other feedback, please feel free to reply. I think my proof of concept will be a separate app for discovery of mutuals on other protocols/networks, not only DeltaChat, since end users will need to pay for the SMS or email verification, and keeping the ser…

There was a proprietary service for this in the past: [image] Keybase Keybase is a key directory that maps social media identities to encryption keys (including, but not limited to PGP keys) in a publicly auditable manner. Additionally it offers an end-to-end encrypted chat and cloud sto…

yeah, i agree, Bluesky can do that because they are public social media.

open source alternative: Keyoxide Modern and secure platform to manage a decentralized identity based on cryptographic keys

[image] adbenitez: hashing doesn’t solve the problem, it is not only about server storing phone numbers, but anyone being able to iterate over phone numbers, generate hash and ask the server for the contact Follow the links, this is addressed in Bluesky RFC and blog post.

Discover mutuals

Bots

ian February 3, 2026, 4:40pm 2

I moved this comment to its separate issue: