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Implement Serverless Payjoin BIP #101

Merged
merged 6 commits into from
Dec 11, 2023
Merged

Implement Serverless Payjoin BIP #101

merged 6 commits into from
Dec 11, 2023

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DanGould
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@DanGould DanGould commented Aug 19, 2023 •
edited

The latest spec: bitcoin/bips#1483

Ongoing design discussion: https://delvingbitcoin.org/t/serverless-payjoin-protocol-design/96

  • Communicate payjoin asynchronously via HTTP Polling(single buffer)
  • Multiple Buffers, BIP21 identification & allocation
  • Base64Url (☐ or Blockchain Commons UR) encoding in BIP21
  • e2ee + authentication
  • Message Padding
  • OHTTP (☐ with 🆕 draft standard secp256k1 HPKE)

Refactors for better production quality

  • Simplify message protocol
  • Make message AEAD part of message packing in send/receive APIs
  • Make OHTTP enc/decapsulation part of send/receive APIs
  • Handle Errors
  • Enable backwards compatibility (☐ pass v1 params, ☐ pjos by default))
  • implement example session management
  • Prefer HPKE to own-rolled cryptosystem
  • Prefer Redis over Postgres since we only need key/value store, not relations
  • Use PSBTv2
  • Use released OHTTP lib vs one with ergonomic changes
  • [ ] Remove workspace (used to simplify testing & features)
  • Use cryptographic hash fn to mark subdirectory instead of concatenating key (which has a header)

Prior Attempts:

@DanGould DanGould added enhancement New feature or request payjoin-cli receive receiving payjoin send sending payjoin relay payjoin networking over a third-party relay api labels Aug 19, 2023
@DanGould DanGould force-pushed the serverless-payjoin branch 2 times, most recently from bb4c1f2 to 9230962 Compare August 23, 2023 16:48
@DanGould DanGould force-pushed the serverless-payjoin branch 2 times, most recently from b47590c to bb2b531 Compare September 12, 2023 17:49
This was referenced Sep 25, 2023
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@DanGould DanGould force-pushed the serverless-payjoin branch 2 times, most recently from c999b55 to 5834266 Compare September 29, 2023 21:56
jbesraa
jbesraa reviewed Oct 2, 2023
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So I just did a review to understand the implementation and link it the actual BIP. I went through the BIP again also while reviewing this so it is a great refreshment. the code is quite readable and its not too hard to link to the different parts of the BIP.
I added a few comments to make sure I get things correctly. Ill review this a couple of more times and might have a bit more code/design input then.

payjoin-cli/src/app.rs Show resolved Hide resolved
payjoin-relay/src/main.rs Outdated Show resolved Hide resolved
payjoin-relay/src/main.rs Outdated Show resolved Hide resolved
@DanGould DanGould force-pushed the serverless-payjoin branch 3 times, most recently from 9eb5cfc to aca9982 Compare November 6, 2023 22:43
@DanGould DanGould force-pushed the serverless-payjoin branch 3 times, most recently from b44a085 to c0ce861 Compare November 20, 2023 22:37
@DanGould DanGould force-pushed the serverless-payjoin branch 2 times, most recently from 28cef51 to e66f80d Compare December 5, 2023 21:04
DanGould
DanGould commented Dec 6, 2023
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payjoin/src/uri.rs Outdated
Comment on lines 174 to 233
} else if endpoint.scheme() == "http" {
Ok(Payjoin::V2Only(PayjoinParams {
_endpoint: endpoint,
disable_output_substitution: pjos.unwrap_or(false),
}))
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Although v2 is secure with plain http because sender - receiver communications are e2ee using hpke, it adds complexity to the library and specifically THIS PR which is now only used in places which also support https

payjoin/Cargo.toml Outdated
@@ -17,6 +17,7 @@ exclude = ["tests"]
[features]
send = []
receive = ["rand"]
relay = []
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this is never used

payjoin-relay/tests/integration.rs Outdated
Comment on lines 268 to 271
let http = reqwest::Client::builder()
.danger_accept_invalid_certs(true)
.build()
.expect("Failed to build reqwest http client");
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Although reqwest is easier to use with tokio than ureq, it's a new dep and makes comparing this to the existing integration more burdenome

payjoin-relay/Cargo.toml Outdated
Comment on lines 21 to 22
reqwest = { version = "0.11.4" } No newline at end of file
reqwest = { version = "0.11.4" }
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sp

payjoin-relay/src/main.rs Outdated
@@ -103,28 +111,50 @@ impl From<hyper::http::Error> for HandlerError {
fn from(e: hyper::http::Error) -> Self { HandlerError::InternalServerError(e.into()) }
}

async fn post_enroll(body: Body) -> Result<Response<Body>, HandlerError> {
use payjoin::{base64, bitcoin};
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these dependencies are independent reexports of payjoin. consider depending on them directly

payjoin/src/uri.rs
@@ -207,7 +265,10 @@ enum InternalPjParseError {
MultipleParams(&'static str),
MissingEndpoint,
NotUtf8(core::str::Utf8Error),
NotBase64(bitcoin::base64::DecodeError),
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cfg feature v2 only?

payjoin/src/v2.rs Outdated
@@ -1,7 +1,6 @@
use std::{error, fmt};

pub const MAX_BUFFER_SIZE: usize = 65536;
pub const RECEIVE: &str = "receive";
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this can actually be removed in the postgres / subdir introduction

payjoin/src/v2.rs
message_a: &mut [u8],
s: SecretKey,
) -> Result<(Vec<u8>, PublicKey), Error> {
pub fn decrypt_message_a(message_a: &[u8], s: SecretKey) -> Result<(Vec<u8>, PublicKey), Error> {
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can this be immutable from the getgo?

payjoin-cli/src/app.rs
#[cfg(feature = "v2")]
async fn long_poll_post(&self, req_ctx: payjoin::send::RequestContext<'_>) -> Result<Psbt> {
loop {
let (req, ctx) = req_ctx.extract_v2(&self.config.ohttp_proxy)?;
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I suppose the loops could be contained within one function that takes this line as a closure

payjoin/src/receive/v2.rs Outdated
Comment on lines 135 to 138
use std::fmt;
use std::str::FromStr;

use serde::de::{self, Deserializer, MapAccess, SeqAccess, Visitor};
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should be at file top

@DanGould DanGould marked this pull request as ready for review December 11, 2023 02:26
@DanGould DanGould force-pushed the serverless-payjoin branch 4 times, most recently from 34d16e0 to e386f4f Compare December 11, 2023 15:14
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This functionality is complete and includes comprehensive testing

However it is rought around the edges and could be a bit more organized with module separation. I'm going to merge it to consider new organizations in independent pull requests

@DanGould DanGould merged commit f87424e into payjoin:master Dec 11, 2023
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This was referenced Dec 11, 2023
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api enhancement New feature or request payjoin-cli receive receiving payjoin relay payjoin networking over a third-party relay send sending payjoin
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