Keychat users can have an unlimited number of IDs, and generating and deleting them is very convenient. You can switch between different IDs by swiping left or right. https://image.nostr.build/3d9bac137fc00395b4a0a4b8f474add3407690917f2caf546def08569c5e545c.jpg https://image.nostr.build/8f36c0ec8c2a7c8bd24cc571442f6d3ab2dcebf724537bfc75ae022342ffc3dc.jpg  nostr:note103pekl3q5wh275dw0zlqwgec2qy7lkp9d7xsk7nuy926xl9805lsj3w6ua


In extreme cases, Keychat can achieve the following:

changing the encryption key for each message,
changing the sending address for each message,
changing the receiving address for each message,
changing the sending relay for each message,
changing the receiving relay for each message. nostr:note1f6vw6cvnp0mt4s3nwakahffwf3qvh4z49kvt93l9gmqy9jpwd2ksfggmq6


satscash is better term than bitcoin ecash?


Yes.


XMPP uses a federated model, like email servers, where servers communicate with each other. Nostr uses a relay model, where relays do not communicate with each other.


So in this case, how do relays prevent spam? The answer is: Bitcoin ecash as a message stamp. nostr:note1f6vw6cvnp0mt4s3nwakahffwf3qvh4z49kvt93l9gmqy9jpwd2ksfggmq6


Yeah, android apk.


I guess 3–4 weeks?


Current chat applications and email have forgotten that an address is not the same as an ID, treating the ID as the address. Emails and current chat applications send messages as [from: Alice's ID to: Bob's ID]. Regardless of how your geographical address changes, when Alice sends an email to Bob, it’s always [from: Alice's ID to: Bob's ID]. This compromises metadata privacy.

However, letters work differently; they are [from: Alice's current geographical address to: Bob's current geographical address].

Keychat separates the receiving address and sending addresses from the ID, and the receiving address and sending addresses are also different. Keychat messages are [from: Alice's one-time sending address to: Bob's almost one-time receiving address]. This makes it difficult for outsiders and relay administrators to determine who is sending messages to whom.

(The new note has modified some expressions, making it clearer.） nostr:note1h842qj25shjm8yrl20y6nlm8yxynlmn33ggu2fj5mh9nmsyjnkgs8pgse4


[Keychat separates the receiving address and sending address from the ID, and the receiving and sending addresses are also different. ]


Current chat applications and email have forgotten that an address is not the same as an ID, treating the ID as the address. Emails and current chat applications send messages as [from: Alice's ID to: Bob's ID]. Regardless of how your geographical address changes, when Alice sends an email to Bob, it’s always [from: Alice's ID to: Bob's ID]. This compromises metadata privacy.

However, letters work differently; they are [from: Alice's current geographical address to: Bob's current geographical address].

Keychat separates the recipient address and sender address from the ID, and the recipient and sender addresses are also different. Keychat messages are [from: Alice's one-time address to: Bob's almost one-time address]. This makes it difficult for outsiders and relay administrators to determine who is sending messages to whom. nostr:note1h842qj25shjm8yrl20y6nlm8yxynlmn33ggu2fj5mh9nmsyjnkgs8pgse4


In practice, when we fill out an envelope, we don’t need to include the sender’s information; we only need to write the recipient’s address, and there’s no need to write the recipient’s name. As long as the recipient’s address is precise enough, the letter can be successfully delivered. Not needing to write the sender’s information is equivalent to being able to write any random address. https://image.nostr.build/a35db954e4d60128e31eb244a487b8108878dbce5e345e6792846827ea35e1b2.jpg  nostr:note13pu0ntgaywtjgfx0lpqlgk4sxxqcnq5aw9fcgrd88jhmuk9ytzcsy46q2c


Hi, Later, we will consider developing a PWA version.


We will release android apk directly.


Another explanation video

https://youtu.be/9sO2qdTci-s?si=1obg30IlQy1xtiiN


If you want to learn more about the double ratchet algorithm, this explanatory video is excellent.

https://youtu.be/7uEeE3TUqmU?si=Sf9ekYhGi2xWFFBV nostr:note1ffgsgvkltl96wzwe6lakv2ntjfkq2u48msx57mrvnnhtyde5s2js8antlr


Good question.

Simplex chat also use signal protocol to achieve end to end encryption.

https://github.com/simplex-chat/simplex-chat/blob/stable/PRIVACY.md

"Simplex chat is the first messenger without user IDs. " This is its most distinctive feature.

“To deliver messages, instead of user IDs used by all other platforms, SimpleX uses temporary anonymous pairwise identifiers of message queues, separate for each of your connections — there are no long term identifiers.”

In my view, Keychat's method of changing the sending and receiving addresses for almost every message is more beneficial for metadata privacy.

I think the number of Simple Chat relays is fewer than the number of Nostr relays. Moreover, the Simplex Chat team has not aimed to integrate with Bitcoin in any way. Could it be said that Simplex Chat does not yet have a viable economic model? https://image.nostr.build/79238f0f305dc434ebb1024f60baf422f34c467398b269541642dcad52c50c2f.png


It is done automatically. Just like encryption key updating automatically.


This image will help you understand the following note. https://image.nostr.build/80cab4c360ea9e4f75ddd70df24b3b59437c49f5eccb51a525475bf866b7029d.jpg  nostr:note1zkkxvfetp5entw9aq3s3jn2e0s5p3kurz0zudprz8ygtaagek64shahcv2


I guess 3-4 weeks?


Wait. We will release code and android apk.


Let's imagine that Alice and Bob are good friends. Alice is traveling in the Americas, and Bob is traveling in Europe, each visiting a new place every day. They have agreed to send each other a letter daily, sharing their travel experiences. Therefore, their sending and receiving addresses are constantly changing.

Similarly, in Keychat, the sending and receiving addresses of messages keep changing just like Alice and Bob's addresses.


Damus relay doesn’t add collect ecash stamp function. So it is free.


Bitcoin and other cryptocurrencies can trace their roots to this earlier, privacy-focussed payment system for the internet.”

About forty years ago, cryptographer David Chaum invented ecash. Ecash is a currency privacy protocol, not a currency itself. However, the fiat banking system did not adopt ecash, leaving the ecash protocol without a viable currency to operate on. But with the advent of Bitcoin, the most open currency, the concept of ecash has been revitalized on Bitcoin. For example, https://cashu.space/

Bitcoin doesn't need ecash. Ecash needs Bitcoin.

https://bitcoinmagazine.com/culture/genesis-files-how-david-chaums-ecash-spawned-cypherpunk-dream


Check this https://cashu.space/


Keychat message’s rawdata https://image.nostr.build/dab9aa71fc88f69d34f5728a67678c49bd986c7e16bb1972004911ecbf8da122.jpg


When we use the term DM, private notes are just an ancillary feature of an application similar to Twitter.

When we use the term chat app, private notes become the core feature. https://image.nostr.build/f179722abbc851e62ff43dad439de72e0f22fb41572f692cd6eef4251c6bb716.jpg  nostr:note1ccua776njq25zed0x5c4ldl3vvnv2w3pafsr5tynhq8u9uxeys3q74nqq0


PWA is worth developing.


If some relays offer free service, no need sats.


No yet. We will release code first.

BTW Keychat primarily reuses libsignal.

https://github.com/signalapp/libsignal


yeah.


When designing Keychat, we considered the following disadvantages of the Signal App.

1、Signal App requires phone number registration. Users do not have their own self-sovereign ID.

2、Signal App users can only use Signal's servers, with no option to use third-party or self-hosted servers.

3、Signal App integrates a shitcoin called MobileCoin.

4、Signal App relies on donations and loans from billionaires, making it difficult to sustain.

Keychat proposed corresponding improvements for these disadvantages.

1、Keychat only requires generating a Nostr key. Users have their own self-sovereign ID.

2、Keychat users can freely choose which relay to use or run their own relay.

3、Keychat aligns with Bitcoin.

4、Keychat's economic model with Bitcoin ecash stamps is more reliable and sustainable.

5、Keychat offers better metadata privacy because it allows continuous changing of receiving addresses, sending addresses, and relays.


The diagram illustrating how Nostr works also uses metaphors like post office and letter. Isn’t it just missing a small stamp?

https://github.com/nostr-protocol/nostr https://image.nostr.build/d19bcfa5ebedf58ed5eea8841e8945ee54555d941c6bcc4ee6ca87453af26784.jpg


I know he is writing a nip about signal protocol.


Nostr - Notes and Other Stuff Transmitted by Relays

Nostr - ( Public and Private )Notes and Other Stuff Transmitted by Relays

For the Nostr ecosystem, applications focused on private notes are just as important as those focused on public notes.


Although Nostr was not specifically designed for private notes, its relay model is most suitable for them. Additionally, compared to public notes, private notes face less censorship because they are encrypted. Private notes require less from Nostr's design.


Different mnemonics can provide better identity separation; for example, if a mnemonic is leaked, it will not lead to the exposure of all IDs.


No. Writing 12 words is easier than writing private key.

12 words == only one pub/pri key pairs.

But Keychat allows users to generate many mnemonic seed phrase. So users can have many IDs.


Just bitcoiner.


Yeah, FAQ page needed.


Keychat implemented NIP 06: Basic key derivation from mnemonic seed phrase

https://github.com/nostr-protocol/nips/blob/master/06.md

So users just need to memorize 12 words to have a self-sovereign ID. https://image.nostr.build/0b18c4bb772dcc7bcb6a6d9f709dbc2e9451c601fe025c06de8c82941a43b5a0.jpg


BTW simplex chat also use signal protocol to achieve end to end encryption.

https://github.com/simplex-chat/simplex-chat/blob/stable/PRIVACY.md https://image.nostr.build/6e9ca2d4106672991db1075306f58c95a05179f2745b7bef62db54e074c72c6f.jpg


Check this post

https://simplex.chat/blog/20230422-simplex-chat-vision-funding-v5-videos-files-passcode.html


Already received by someone.

No one knows who collected.


If you have not seen ecash sats, 👇

( You can try to get this 21 sats)

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 https://image.nostr.build/ccdb4bf3757a9b24c80144bd42534a5ae61b871f56c060c15b75f2d87db823b5.jpg


The reason Keychat is so adamant about using Bitcoin ecash as stamps is that free services are unsustainable.

A blog post by Signal from last year discusses the costs and losses involved in running Signal.

"We estimate that by 2025, Signal will require approximately $50 million dollars a year to operate.”

https://signal.org/blog/signal-is-expensive/


Thanks for your appreciation. We will release code and apk sooooon.


During our testing period, 1 sat equals 1 stamp. So if you send 50 messages every day, you need 50 sats. Currently, one cent can buy about 16 sats, so you spend 3 cents a day, which is 90 cents a month. Is that expensive?

Pay with privacy or pay with ecash https://image.nostr.build/58f8498a0a642cffe13413961952d62f2f262daaaa656dad4a11a62a5e9d32ff.jpg


Got it.

Now Keychat focus on private note, aka chat app.

I think public note can also use bitcoin ecash stamp. It is also possible his fans pay ecash to get his latest post.

Keychat relay only add collecting bitcoin ecash function. If the relay operator provides free service, current relays e.g., Damus relay can be used as Keychat relay.

Nostr relay operators can also be one cashu mint. Keycaht now using the third party cashu mints.


custody Lightning network is much worse than bitcoin ecash.


“If I have $50 of Bitcoin on the Lightning network. I don't care about custody.”

yes，custody Lightning network is shitcoin.


We believe that small, anonymous pay-per-use payments are preferable to subscriptions. Implementing small pay-per-use payments on the internet used to be difficult, until the advent of Bitcoin ecash.


The reason we dislike the subscription model is that it requires a fixed public key. A fixed public key can compromise the privacy of metadata in encrypted messages. Stamp pricing would be generated through competition among relays. Different prices could correspond to different storage durations.


The Nostr protocol is bold; it bravely uses public/private keys as the user's ID. Previously, too many people said that users were too foolish to safeguard their private keys.

We should also boldly imagine that users might accept attaching a Bitcoin ecash stamp to each note.


Take Phoenix LN wallet for example. Fees of Sending via Lightning	0.4 % + 4 sat

https://phoenix.acinq.co/faq#what-are-the-fees

The fee-free mode of custodial Lightning Network wallets has misled many people into thinking that the Lightning Network is very cheap.


Not released now. Plz wait.


Because relay operators need to pay for server-related expenses. SimpleX relay operators also need to pay server-related expenses.


Because in the Lightning Network, payments require multiple interactions to succeed. Additionally, the transaction fees for self-hosted Lightning Network transactions are very expensive.


Nostr users are awesome. Until now no one replied like pay ecash to message is stupid idea.

Nostr users understand that:

There is no long-lasting free lunch.

In many cases, free is the most expensive.

Pay with privacy or Pay with ecash nostr:note16gv0dfkfaj2cvyujxlk9thckm4vy63r9vl0hpcn9473flca9qqqscm583q


Agree.


We will release code and android apk at the same time.


Using your lightning sats to mint ecash sats. https://image.nostr.build/61805b646754bcfc514dcd4065cdd99886a0ed01755dbfaef59c70012a230727.jpg


It’s possible. You just need to ask him to transfer ecash.

In Keychat, transferring ecash is just a message.Very easy.


Almost no one cares about Bcash anymore.

We think bitcoin ecash will be popular.


Users choose which relay to use. Relays set their own prices, although some may offer services for free.


Yeah, check this post

nostr:note1ffgsgvkltl96wzwe6lakv2ntjfkq2u48msx57mrvnnhtyde5s2js8antlr


Does anyone still remember the relationship between Twitter and Signal?

“Whisper Systems was an American enterprise mobile security company that was co-founded by security researcher Moxie Marlinspike and roboticist Stuart Anderson in 2010.[1] The company was acquired by Twitter in November 2011.[2][3][4] Some of the company's software products were released under open-source licenses after the acquisition.[5] An independent group called Open Whisper Systems later picked up the development of this open-source software,[6] which led to the creation of the Signal Technology Foundation.”

https://en.wikipedia.org/wiki/Whisper_Systems


Yeah, Cashu supports Pay to Public Key (P2PK).

ehttps://github.com/cashubtc/nuts/blob/main/11.md

Keychat stamp is just normal cashu ecash.


Public. The relay is the first to receive the ecash stamp, so it can collect it. It's like the stamp is affixed on the envelope, not inside it.


Many Nostr users know that the Signal protocol is a very secure end-to-end encryption protocol, recommended by Snowden. However, many people do not know why the Signal protocol is secure. In fact, the design of the Signal protocol has a historical basis and is very intuitive and simple.

End-to-end encryption protocols have gone through three key stages: the PGP (Pretty Good Privacy) protocol of the 1990s, the OTR (Off The Record) protocol of the 2000s, and the Signal protocol of the 201x.

PGP achieved end-to-end encryption through public key encryption. But if a private key leaks, all [past and future] messages can be decrypted. No [forward secrecy] and [backward secrecy].

[[In the PGP protocol, the identity key and the encryption key are the same; it serves as both the identity and is used to encrypt messages.]] [[As an identity key, it is a long-term key, and the longer it is used, the greater the likelihood of private key exposure.]]

The OTR protocol solves the problem of PGP. Its approach is simple: [[it separate the identity key from the encryption key and generates a unique encryption key for each conversation, which is deleted after use.]]

The Signal protocol inherited ideas from the OTR protocol. It mainly consists of two parts: the X3DH protocol, which is responsible for the initial key agreement, and the Double Ratchet Algorithm, which is responsible for deriving encryption keys. [[The Signal protocol derives a new encryption key for each message, which is deleted after use.]] It achieved better forward and backward secrecy.

BTW, the Signal protocol is not equivalent to the Signal app. WhatsApp also uses the Signal protocol for end-to-end encryption. The Signal protocol is only responsible for the end-to-end encryption of messages, meaning only the communicating parties can decrypt the content, not even the server administrators.


I think it is possible. Give all relays who routed the message bitcoin ecash. Just like using 10 letter envelops, every envelop has one stamp.


https://www.erisian.com.au/wordpress/2004/02/07/email-fees-and-viruses

“The real benefits of email postage compared to other money-based solutions is that it’s broad-based and fair (no one has to worry about following a different system to anyone else, which is a nice equalising property of the Internet that’s worth retaining, and there aren’t areas for big businesses to position themselves so they can extort money from users); that it is implementable entirely at the endpoints (you just need to upgrade mutt or Outlook, you don’t need to change ISPs), that it’s flexible (you can change the fees you expect depending on who the mail’s from, who it’s to, or what it’s about), and it has very few external costs (you don’t need to reimplement the internet, you don’t need to create a new police taskforce, or put more cases through the courts, or add lots of new restrictions to ISPs — basically it has the property when people don’t follow the rules, you just don’t get their mail, you don’t get hurt and have to seek a remedy).”

nostr:npub12rv5lskctqxxs2c8rf2zlzc7xx3qpvzs3w4etgemauy9thegr43sf485vg Maybe you are interested in this 20 years ago post.


Ancient letters are a remarkable invention, as they contain both information (the message) and value (the stamp). In contrast, modern emails and messengers only contain information, lacking value. Service providers can't solve the spam problem and must rely on registration systems. Letters, using stamps, solved this problem more elegantly without the need for registration. nostr:note16gv0dfkfaj2cvyujxlk9thckm4vy63r9vl0hpcn9473flca9qqqscm583q


Thanks. Modified.


The Signal protocol is only responsible for encrypting and decrypting messages.

Yeah, Keychat uses Signal protocol to encrypt / decrypt message.


Yes, it’s possible. Bitcoin ecash as estamp is general solution.


Information and value are compressed into the same message, and both are sent out simultaneously; this is a very exciting thing. nostr:note1te6qfvlelcazh4auesdaukz0v8zuk0nr3eqsquq5lmtsnr28r9hq5zv2w6


Do you mean https://sphinx.chat ?

Bitcoin lightning network is one financial network, maybe too expensive to be used as normal communication.


Signal protocol =/= Signal app. WhatsApp also use signal protocol to achieve end to end encryption.

So keychat users can’t interact with signal app users.


Yes, nostr relays get those ecash stamp.

We think there is no long-lasting free lunch. So we learn from postal system. Ecash is best e-stamp. relay will be post office, which has income to cover cost.


By Bitcoin ecash, we mean Cashu.

https://cashu.space nostr:note16gv0dfkfaj2cvyujxlk9thckm4vy63r9vl0hpcn9473flca9qqqscm583q


https://image.nostr.build/a35db954e4d60128e31eb244a487b8108878dbce5e345e6792846827ea35e1b2.jpg  nostr:note16gv0dfkfaj2cvyujxlk9thckm4vy63r9vl0hpcn9473flca9qqqscm583q


Bitcoin ecash is the best estamp.

Stamps are made of paper, and so are envelopes, which makes it convenient for stamps to be attached to envelopes. Ecash is a piece of data, and the encrypted message is also a piece of data; the two can easily be combined together. nostr:note16gv0dfkfaj2cvyujxlk9thckm4vy63r9vl0hpcn9473flca9qqqscm583q


We are pleased to find a very good 【prototype】; people can easily understand the postal system, which allows them to comprehend ecash as e-stamps, Nostr relays as post offices, and the necessity for messages themselves to be end-to-end encrypted. Messages need to continuously update the recipient and sender addresses.


Hi, we prefer nostr only, so no email subscription.

You won’t miss apk release if you followed this account.


Can you see one purple bird in Keychat logo? https://image.nostr.build/3fd11c507f2f4b386b88806124e50d469210399957d21a729d5cde0c5f0834ad.jpg


Code will be released soon.

Keychat doesn’t support syncing on multiple devices. Every device has its own ID. And those devices can communicate through group chat.

It’s very hard to support syncing for double ratchet algorithm. More difficult in conditions there is no coordination server.


>>Keychat fully reuse signal protocol.


Hi Jeff. About message encryption, Nostrat fully reuses the Signal protocol (X3DH + double ratchet) and reuses libsignal.

First, let's return to the mechanism of the Signal app. The Signal app uses phone numbers as user IDs. When Alice downloads the Signal app and knows Bob's phone number, she adds Bob as a Signal friend by entering Bob's phone number in the Signal app. The Signal server then returns the following data associated with Bob's phone number:

Bob's identity key IKB,
Bob's signed prekey SPKB,
Bob's prekey signature Sig(IKB, Encode(SPKB)),
(Optionally) Bob's one-time prekey OPKB.

Alice then combines this with her own identity key IKA and her ephemeral key EKA to complete the X3DH operation, and then initiates the double ratchet algorithm to start encrypting messages. When Bob receives the message, he can also initiate the double ratchet to decrypt the message.

Let's now assume that Alice and Bob have both downloaded Keychat and want to communicate using it. Bob displays his QR code, which contains his Nostr key and Signal-related keys. Alice scans it. Alice can then complete the X3DH operation and start the double ratchet encryption. It can be said that Keychat, unlike Signal, does not use a server to pass the related Signal keys. Keychat treats the Nostr key as a phone number. If Alice only knows Bob’s Nostr key, she can send a special NIP4 message to retrieve Bob’s related Signal keys.


No, just need nostr relay as post office.

Encryption/decryption is processed on client.


Yes, of course 😉


Pay with privacy

OR

Pay with ecash


There is no long-lasting free lunch.


Keychat message is also kind 4 event. So Keychat can use all relays which supports kind 4.

The difference between Keychat messages and DM messages is encryption/decryption methods, which processed in client. Relays don’t care about encryption.


The current Nostr DM (NIP4)  integrates four capabilities into a single Nostr key—it serves as an ID, an encryption key, a receiving address, and a sending address.

In Keychat, the ID, encryption key, receiving address, sending address are separated, allowing the encryption key , the receiving and sending addresses to be updated continually. This achieves better encryption security (forward secrecy and backward secrecy) and metadata privacy.


It is interoperable. Keychat relay only add collecting bitcoin ecash function. If the relay operator provides free service, current relays e.g., Damus relay can be used as Keychat relay.

The android apk will be released first, then the code.


nostr:npub180cvv07tjdrrgpa0j7j7tmnyl2yr6yr7l8j4s3evf6u64th6gkwsyjh6w6  nostr:npub12rv5lskctqxxs2c8rf2zlzc7xx3qpvzs3w4etgemauy9thegr43sf485vg


The Introduction of Keychat

Keychat is a chat app, built on Bitcoin ecash, Nostr protocol and Signal protocol.

Keychat is inspired by the postal system — stamps, post offices, letters.

Keychat uses Bitcoin ecash as stamps and Nostr relays as post offices.

Senders send messages stamped with Bitcoin ecash to Nostr relays. The Nostr relays collect the Bitcoin ecash, then deliver messages to receivers.

Unlike the centralized postal system, Keychat can use multiple Bitcoin ecash issuers and Nostr relays, each maintained by distinct operators.

Keychat uses Signal protocol to ensure message encryption security and meta-data privacy.

The content of the letter can be exposed easily by opening the envelope. Keychat messages are end-to-end encrypted via Signal protocol, with a unique encryption key generated for each message. Only the sender and receiver can decrypt the message.

The addresses of both parties on the envelope can be tracked. In theory, this problem is solved if they change addresses daily. So Keychat reuses Signal protocol to update sending and receiving addresses for nearly every message.

Like the postal system, Keychat requires no registration. Users just generate Nostr keys as ID.

https://www.keychat.io/