Yaacov Akiba Slama [ARCHIVE]

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🗓️ Active from 2019-10-30 to 2019-11-14
💬 Posted a total of 11 messages
📚 Participated in the following categories: Lightning-dev, VERY ROUGH DRAFT
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2023-06-09 14:57:19 CEST

- reply

📅 Original date posted:2019-11-12
📝 Original message:
On 11/11/2019 06:11, Rusty Russell wrote:
> 2) From a technical point of view, it seems that there are already UBL
> libraries in java and c#. I don't think such library is hard to write in
> go, rust.., so every wallet implementation can use them.
> That is not the problem. The problem is that our order flow is simple:
>
> Seller: Offer
> Buyer: Invoice Request
> Seller: Invoice (or updated Offer)
> Buyer/Seller: Payment & Acknowledgement (atomic)
>
> (This could, of course, fit into a larger business flow.)
>
> The closest UBL flow seems to be:
>
> Seller: Quotation
> Buyer: Order
> Seller: (Prepayment)Invoice (or updated Quotation)
In UBL, 2 flows are defined (Traditional and Self Billing) and from what
I know, the right flow depends on the country and even on the industry
(services or goods for instance). What I suggest is to superpose the
"strict" LN flow (invoice then payment) to the business flow. So for
instance when a prepayment invoice is needed, the simplified (from UBL
pov) flow will be:
Seller: Quotation (UBL)
Buyer: Order (UBL)
Seller: Prepayment Invoice (UBL)
Seller: Invoice (LN)
Buyer/Seller: Payment & Ack (LN)
Buyer: Receipt (UBL)
The advantage of such workflow are that we don't need to add any fields
to the current invoice structure, nor to define in the LN protocol new
messages like offer or invoice request, nor to intervene in the semantic
of the business workflow and in the required/optional fields in these
messages.
>
> It's also worth noting that, even compressed, none of the UBL examples
> fit into the 1023 byte limit of the existing invoice format:
>
> UBL-Quotation-2.1-Example.xml: 1864 bytes (gz)
> UBL-Order-2.1-Example.xml: 2515 bytes (gz)
> UBL-Invoice-2.1-Example.xml: 3163 bytes (gz)
>
> Indeed, that Quotation alone requires a 32x32 QR code.
>
>>> However, since invoices/offers and UBL are both structures, we
>>> should have an explicit mapping between the two. What fields should
>>> have their own existence in the invoice/offer and what should be in a
>>> general UBL field is a question we have to think on further.
>> I agree that we don't want duplication. This is the reason, I propose to
>> use only ubl structure and add in the ln standard invoice an ubl
>> "opaque" field which will be self-contained and only add in the
>> invoice/offer/.. the fields specific to ln.
> Except we need to go through the UBL spec and indicate exactly what
> fields are permitted, and which are required.
>
> Many UBI fields are not amenable to machine interpretation (eg. note
> fields). These must be either explicitly exposed to the buyer (in case
> the seller uses them) such as shipping conditions, or explicitly
> forbidden/ignored.
>
> This is not a small task, and required intimiate knowledge of the UBL
> spec. It's not enough just to make something *look* like UBL.
>
> Does anyone have expertise in this area? Shall we form a sub-group to
> investigate this properly?
>
> Thanks!
> Rusty.
>

2023-06-09 14:57:17 CEST

- reply

📅 Original date posted:2019-11-08
📝 Original message:
Hi Rusty.
On 08/11/2019 05:09, Rusty Russell wrote:
> Hi Yaacov,
> I've been pondering this since reading your comment on the PR!
>
> As a fan of standards, I am attracted to UBL (I've chaired an
> OASIS TC in the past and have great respect for them); as a fan of
> simplicity I am not. Forcing UBL implementation on wallet providers is
> simply not going to happen, whatever I were to propose.
In fact, using UBL in LN specification is simpler than trying to
understand the semantic of each field needed by businesses. You are
right that using such a standard put the burden into wallet providers
instead of LN developers, but as a wallet (breez) provider, I can say that:
1) Most money transactions (currently in fiat) are between users and
companies and not between two users. If we want to replace FIAT by
bitcoin, we need to create an infrastructure which can be used by
businesses. That means that LN needs to be able to be integrated easily
into POS systems. So, as a wallet provider who want to help the
transition from fiat to bitcoin, I need to be able to support standards
even if that means that I have to implement using/parsing big and
complicated standards.
For simple user to user transaction, the wallet can decide to use only a
subset of the fields defined by the standard.
2) From a technical point of view, it seems that there are already UBL
libraries in java and c#. I don't think such library is hard to write in
go, rust.., so every wallet implementation can use them.
>
> We also don't want duplication; what if the "UBL field" were to
> say I were selling you a bridge for $1 and the description and amount
> fields actually said I was selling you a coffee for $3?
>
> However, since invoices/offers and UBL are both structures, we
> should have an explicit mapping between the two. What fields should
> have their own existence in the invoice/offer and what should be in a
> general UBL field is a question we have to think on further.
I agree that we don't want duplication. This is the reason, I propose to
use only ubl structure and add in the ln standard invoice an ubl
"opaque" field which will be self-contained and only add in the
invoice/offer/.. the fields specific to ln.
> Anyway, you'll have to bear with me as I read this 172 page
> standard...
Sure :-)
BTW, Thanks a lot for your all your work. LN would not have been where
it is without your push.

2023-06-09 14:57:16 CEST

- reply

📅 Original date posted:2019-11-05
📝 Original message:
Hi Rusty,
It seems that there are two kind of TLV fields in your proposition:
1) LN specific fields like `num_paths` and `payment_preimage`.
2) "Business" fields like `address1` and `currency`.
I understand the need to define and include the first category, but I
don't think that we need or can define the second category. These fields
already exists in software like crm, erp, etc.. and are well defined by
standard body.
My suggestion is to have a generic field containing well defined
structured and standardized data. See for instance
https://en.wikipedia.org/wiki/EDIFACT and/or
https://en.wikipedia.org/wiki/Universal_Business_Language.
What do you think?
PS: Sorry for crossposting here and in
https://github.com/lightningnetwork/lightning-rfc/pull/694
--yas
On 05/11/2019 06:23, Rusty Russell wrote:
> Hi all,
>
> This took longer than I'd indicated; for that I'm sorry.
> However, this should give us all something to chew on. I've started
> with a draft "BOLT 12" (it might be BOLT 13 by the time it's finalized
> though!).
>
> I've also appended indications where we touch other BOLTs:
> 1. BOLT 7 gains a message/reply system, encoded like htlc onions and
> failure messages.
> 2. BOLT 11 gains a `q` field for quantity; this avoids changing the
> description when the user requests an invoice for more than one of something
> (since changing the description between offer and invoice requires user
> interaction: it's the *invoice* which you are committing to).
>
> There's definite handwaving in here; let's see if you can find it!
>
> Cheers,
> Rusty.
>
> # BOLT #12: Offer Protocols for Lightning Payments
>
> An higher-level, QR-code-ready protocol for dealing with invoices over
> Lightning. There are two simple flows supported: in one, a user gets
> an offer (`lno...`) and requests an invoice over the lightning
> network, obtaining one (or an error) in reply. In the other, a user
> gets an invoice request (`lni...`), and sends the invoice over the
> lightning network, retreiving an empty reply.
>
> # Table of Contents
>
> * [Offers](#offers)
> * [Encoding](#encoding)
> * [TLV Fields](#tlv-fields)
> * [Invrequests](#invrequests)
> * [Encoding](#encoding)
> * [TLV Fields](#tlv-fields)
>
> # Offers
>
> Offers supply a reader with enough information to request one or more
> invoices via the lightning network itself.
>
> ## Encoding
>
> The human-readable part of a Lightning offer is `lno`. The data part
> consists of three parts:
>
> 1. 0 or more [TLV](01-messaging.md#type-length-value-format) encoded fields.
> 2. A 32-byte nodeid[1]
> 3. 64-byte signature of SHA256(hrp-as-utf8 | tlv | nodeid).
>
> ## TLV Fields
>
> The TLV fields define how to get the invoice, and what it's for.
> Each offer has a unique `offer_idenfitier` so the offering node can
> distinguish different invoice requests.
>
> Offers can request recurring payments of various kinds, and specify
> what base currency they are calculated in (the actual amount will be
> in the invoice).
>
> `additional_data` is a bitfield which indicates what information the
> invoice requester should (odd) or must (even) supply:
> 1. Bits `0/1`: include `delivery_address`
> 2. Bits `2/3`: include `delivery_telephone_number`
> 3. Bits `4/5`: include `voucher_code`
> 4. Bits `6/7`: include `refund_proof`
>
> `refund_for` indicates an offer for a (whole or part) refund for a
> previous invoice, as indicated by the `payment_hash`.
>
> 1. tlvs: `offer`
> 2. types:
> 1. type: 1 (`paths`)
> 2. data:
> * [`u16`:`num_paths`]
> * [`num_paths*path`:`path`]
> 1. type: 2 (`description`)
> 2. data:
> * [`...*byte`:`description`]
> 1. type: 3 (`expiry`)
> 2. data:
> * [`tu64`:`seconds_from_epoch`]
> 1. type: 4 (`offer_identifier`)
> 2. data:
> * [`...*byte`:`id`]
> 1. type: 5 (`amount`)
> 2. data:
> * [`4*byte`:`currency`]
> * [`tu64`:`amount`]
> 1. type: 6 (`additional_data`)
> 2. data:
> * [`...*byte`:`rbits`]
> 1. type: 7 (`recurrance`)
> 2. data:
> * [`byte`:`time_unit`]
> * [`u32`:`period`]
> * [`tu32`:`number`]
> 1. type: 8 (`recurrance_base`)
> 2. data:
> * [`u32`:`basetime`]
> * [`tu32`:`paywindow`]
> 1. type: 9 (`quantity`)
> 2. data:
> * [`tu64`:`max`]
> 1. type: 10 (`refund_for`)
> 2. data:
> * [`32*byte`:`payment_hash`]
>
> 1. subtype: `path`
> 2. data:
> * [`u16`:`num_hops`]
> * [`num_hops*hop`:`hops`]
>
> 1. subtype: `hop`
> 2. data:
> * [`pubkey`:`nodeid`]
> * [`short_channel_id`:`short_channel_id`]
> * [`u16`:`flen`]
> * [`flen*byte`:`features`]
>
> ## Requirements For Offers And Invrequests
>
> A writer of an offer or an invrequest:
> - if it is connected only by private channels:
> - MUST include `paths` containing a path to the node.
> - otherwise:
> - MAY include `paths` containing a path to the node.
> - MUST describe the item(s) being offered or purpose of invoice in `description`.
> - MUST include `expiry` if the offer/invrequest will not be valid after some time.
> - if it includes `expiry`:
> - MUST set `seconds_from_epoch` to the expiry time in seconds since 1970 UTC.
>
> ## Requirements For Offers
>
> A writer of an offer:
> - MUST use a unique `offer_idenfitier` for each offer.
> - MAY include `recurrence` to indicate offer should trigger time-spaced
> invoices.
> - MUST include `amount` if it includes `recurrence`.
> - if it includes `amount`:
> - MUST specify `currency` as the ISO 4712 or BIP-0173, padded with zero bytes if required
> - MUST specify `amount` to the amount expected for the invoice, as the ISO 4712 currency unit multiplied by exponent, OR the BIP-0173 minimum unit (eg. `satoshis`).
> - if it requires specific fields in the invoice:
> - MUST set the corresponding even bits in the `additional_data` field
>
> A reader of an offer:
> - SHOULD gain user consent for recurring payments.
> - SHOULD allow user to view and cancel recurring payments.
> - SHOULD gain user consent to send `delivery_` fields.
> - if it uses `amount` to provide the user with a cost estimate:
> - MUST warn user if amount of actual invoice differs significantly
> from that expectation.
> - FIXME: more!
>
> ## Recurrance
>
> Some offers are *periodic*, such as a subscription service or monthly
> dues, in that payment is expected to be repeated. There are many
> different flavors of repetition, consider:
>
> * Payments due on the first of every month, for 6 months.
> * Payments due on every Monday, 1pm Pacific Standard Time.
> * Payments due once a year:
> * which must be made on January 1st, or
> * which are only valid if started January 1st 2020, or
> * which if paid after January 1st you (over) pay the full rate first year, or
> * which if paid after January 1st are paid pro-rata for the first year, or
> * which repeat from whenever you made the first payment
>
> Thus, each payment has:
> 1. A `time_unit` defining 0 (seconds), 1 (days), 2 (months), 3 (years).
> 2. A `period`, defining how often (in `time_unit`) it has to be paid.
> 3. An optional `number` of total payments to be paid.
> 4. An optional `basetime`, defining when the first payment applies
> in seconds since 1970-01-01 UTC.
> 5. An optional `paywindow`, defining how many seconds into the period
> a payment will be accepted: 0xFFFFFFFF being a special value meaning
> "any time during the period, but you will have to pay proportionally
> to the remaining time in the period".
>
> Note that the `expiry` field covers the case where an offer is no longer
> valid after January 1st 2020.
>
> ## Default Offer
>
> The "default offer" of a node is a nominal offer used to send
> unsolicited payments. It is generally not actually sent, but can be
> used by any other node as if it has been. It has the following
> fields:
>
> * `offer_idenfitier`: zero-length
> * `d`: any
> * `n`: the node id of the recipient.
>
> ## Invoice Request Encoding
>
> Once it has an offer, the node can request an actual invoice using the
> `invoice_req` message inside `directed`'s `onion_routing_packet`. It
> would expect an `invoice_or_error_tlv` inside the `directed_reply`
> message.
>
> This includes a `tag` it can use to identify replies, the
> `offer_idenfitier` from the offer, a `key` it can use to prove it was
> the requester of this invoice, a `recurrence` number if this
> is a payment in a recurring series, and other codes as required.
>
> The `refund_proof` refers to a previous invoice paid by the sender for
> the specific case of a `refund_for` offer. It provides proof of
> payment (the `payment_preimage` and also a signature of the
> `payment_hash` from the `key` which requested the being-refunded
> invoice (which does *not* have to be the same as this `key`!).
>
> 1. tlvs: `invoice_request_tlv`
> 2. types:
> 1. type: 1 (`tag`)
> 2. data:
> * [`...*byte`:`tag`]
> 1. type: 2 (`offer_identifier`)
> 2. data:
> * [`...*byte`:`id`]
> 1. type: 3 (`key`)
> 2. data:
> * [`32`:`key`]
> 1. type: 4 (`recurrence`)
> 2. data:
> * [`tu64`:`number`]
> 1. type: 5 (`quantity`)
> 2. data:
> * [`tu64`:`n`]
> 1. type: 6 (`delivery_address_name`)
> 2. data:
> * [`...*byte`:`name`]
> 1. type: 7 (`delivery_address1`)
> 2. data:
> * [`...*byte`:`address1`]
> 1. type: 8 (`delivery_address2`)
> 2. data:
> * [`...*byte`:`address2`]
> 1. type: 9 (`delivery_city`)
> 2. data:
> * [`...*byte`:`city`]
> 1. type: 10 (`delivery_state_province_or_region`)
> 2. data:
> * [`...*byte`:`state_province_or_region`]
> 1. type: 11 (`delivery_zip_or_postal_code`)
> 2. data:
> * [`...*byte`:`zip_or_postal_code`]
> 1. type: 12 (`delivery_country`)
> 2. data:
> * [`2*byte`:`country_code`]
> 1. type: 13 (`delivery_telephone_number`)
> 2. data:
> * [`...*byte`:`tel`]
> 1. type: 14 (`voucher_code`)
> 2. data:
> * [`...*byte`:`code`]
> 1. type: 15 (`refund_proof`)
> 2. data:
> * [`32*byte`:`payment_preimage`]
> * [`signature`:`signature`]
>
> ## Requirements
>
> FIXME: many more
> Sender MUST use ISO 3166 alpha-2 code for `delivery_country`.
> Sender MUST set offer_identifier to match offer.
> Sender MUST include `key`
> - SHOULD use a transient unpredictable key
> - MUST reuse key for successive recurring invoices.
> Sender MUST set `recurrence` for recurring invoices.
>
> Receiver MUST check `offer_identifier`
> Receiver MUST check `delivery_` fields.
> Receiver MUST check `recurrence`.
> Receiver MUST check `amount`.
>
> 1. tlvs: `invoice_or_error_tlv`
> 2. types:
> 1. type: 1 (`tag`)
> 2. data:
> * [`...*byte`:`tag`]
> 1. type: 3 (`omitted`)
> 2. data:
> * [`...*u64`:`omitted_fields`]
> 1. type: 4 (`invoice`)
> 2. data:
> * [`...*byte`:`invoice`]
> 1. type: 5 (`message`)
> * [`...*byte`:`message`]
> 1. type: 6 (`replacement`)
> 2. data:
> * [`signature`:`signature`]
> * [`...*byte`:`offer`]
>
> Sender:
> - MUST copy `tag` from sender.
> - MUST omit fields it does not use, and place number in order in `omitted_fields`.
> - if it includes `invoice`:
> - MUST not include `message`
> - MUST not include `replacement`
> - MUST [merkle fields it used](#merkle-calculation) and place that in invoice `s` field.
> - otherwise, if it includes `replacement`:
> - MAY include `message`
> - otherwise:
> - MUST include `message` describing the error.
>
> Receiver:
> - MUST check that `tag` matches req.
> - if `replacement`:
> - MUST fail if `signature` does not sign `offer` with same key as original.
> - MUST only fetch once (no double-redirects!)
> - if description or amount significantly changes, must re-ask user.
> - SHOULD note if description simply has something appended (eg "+ postage").
> - within invoice:
> - MUST check that `s` matches merkle of fields, minus `omitted`.
> - MUST check that no vital fields are in `omitted`.
> - MUST check that `d` matches `description`
> - MUST check that `q` DNE if `quantity` DNE, otherwise is equal.
> - Must check valid signature, etc.
>
> ## Merkle Calculation
>
> 1. For each `invoice_req_tlv` field in ascending `tlv` type order:
> 1. If the field was omitted, it is added to `omitted_fields`.
> 2. Otherwise, the immediate parent merkle is:
>
> SHA256(SHA256(`tag` | `be64-n`) | SHA256(`tlv-value`))
>
> Where `be64-n` is a 64-bit big-endian counter starting at 0 and
> incrementing for each leaf.
>
> 3. Order these nodes in increasing SHA256(`tag` | `be64-n`) order.
>
> 2. Create additional leaves until `be64-n` is the next power of 2:
>
> SHA256(`tag` | `be64-n`)
>
> 3. Combine adjacent leaves using SHA256(leaf1 | leaf2) until none remain.
>
> By creating adjacent leaves using the `tag` field and a counter, and
> sorting the leaves, the only significant information revealed by a
> merkle proof on a node is the depth of tree (which implies the total
> number of TLV fields).
>
> # InvRequests
>
> There are times when it makes sense to request an invoice over another
> medium, such as HTTP or a QR code.
>
> ## Encoding
>
> The human-readable part of a Lightning invrequest is `lni`. The data part
> consists of three parts:
>
> 1. 0 or more [TLV](01-messaging.md#type-length-value-format) encoded fields.
> 2. A 32-byte nodeid[1]
> 3. 64-byte signature of SHA256(hrp-as-utf8 | tlv | nodeid).
>
> ## TLV Fields
>
> 1. tlvs: `invreq`
> 2. types:
> 1. type: 1 (`paths`)
> 2. data:
> * [`u16`:`num_paths`]
> * [`num_paths*path`:`path`]
> 1. type: 2 (`description`)
> 2. data:
> * [`...*byte`:`description`]
> 1. type: 3 (`expiry`)
> 2. data:
> * [`tu64`:`seconds_from_epoch`]
> 1. type: 4 (`amount`)
> 2. data:
> * [`tu64`:`millisatoshis`]
>
> The fields `paths`, `description`, and `expiry` fields are the
> same as those for offers; the optional `amount` field describes the
> amount an invoice will be accepted for.
>
> Upon parsing and accepting an `invreq`, the node sends an
> `invoice_or_error_tlv` within an onion. The reply is empty.
>
> ## Requirements
>
> The requirements for `paths`, `description` and `expiry` are
> [described above](#requirements-for-offers-and-invrequests).
>
> FIXME: More.
>
> [1] Assuming we go for Schnorr sigs and 32-byte pubkeys.
> ----
> Addendum: BOLT #7: P2P Node and Channel Discovery and Directed Messages
> ...
> # Directed Messages
>
> Directed messages allow peers to use existing connections to query for
> invoices (see [BOLT 12](12-offer-encoding.md)). Like gossip messages,
> they are not associated with a particular local channel.
>
> The `id` is a unique, transient identifier between the peers, used to
> identify match messages and replies.
>
> ## The `directed` and `directed_reply` Messages
>
> 1. type: 384 (`directed`) (`option_directed_messages`)
> 2. data:
> * [`chain_hash`:`chain_hash`]
> * [`u64`:`id`]
> * [`1366*byte`:`onion_routing_packet`]
>
> 1. type: 384 (`directed_reply`) (`option_directed_messages`)
> 2. data:
> * [`chain_hash`:`chain_hash`]
> * [`u64`:`id`]
> * [`u16`:`len`]
> * [`len*byte`:`reply`]
>
> ## Requirements
>
> FIXME: similar to update_add_htlc and update_fail_htlc.
> FIXME: define reasonable timeout after which you can forget if not replied?
> _______________________________________________
> Lightning-dev mailing list
> Lightning-dev at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev

2023-06-09 14:57:13 CEST

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📅 Original date posted:2019-11-09
📝 Original message:
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2023-06-09 14:57:13 CEST

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📅 Original date posted:2019-11-09
📝 Original message:
[Sorry: re-sending again in plain text]
On 08/11/2019 16:15, Joost Jager wrote:
>
> > The goal of this pre-payment proposal is to remove the need for
> > trusted parties
> >
> > Trust isn't the right word. It is a level of service that you
> provide
> > to your peers. If nodes are cognizant of the fact that the level of
> > service they receive goes down if they forward spam, they will be
> > careful on the incoming side. Require peers to build up a
> reputation
> > before increasing the inbound limits that apply to the channels
> with them.
>
> We can learn from the current situation in emails, that a system
> based
> on reputation tends to concentrate the power in the hands of few
> big and
> strong actors (gmail and co). If we have from the beginning a
> mechanism
> to fight against spam by paying to send message, we can perhaps
> have a
> really distributed system which cannot be censured.
>
>
> Can you elaborate on this a bit further? If you consider rate limiting
> to be a form of censoring, then you can still censor if there is a prepay.
There are situations when lot of people need to send each other lot of
messages in a small period of time, in protests for instance. In this
case, people are ready to pay a little to communicate. It's true that
they can be censored even when paying for messaging, but in this case,
it's a voluntary (and politic) decision. But when using a rate limiting
mechanism, it's an economic decision with politic implications.
>
> I am not too familiar with the current state of email servers, to what
> extent power is concentrated now and how that evolution translates to
> Lightning.
Currently, if you install a smtp server in you home computer or in a
server you rent and you try to send an email to someone with an email
from any big provider, it will be marked as spam, because you need to
have a good "reputation". And if you try to send so called "marketing"
emails, you'll be marked as spammer even if the same emails sent by big
providers are not rejected. This is the effect of using any reputation
system. The path from reputation to propaganda is very short.
> One difference is that afaik emails don't traverse a path through
> multiple mail "nodes". Another is that inboxes of users are very
> centralized (gmail and co).
I can imagine a system where people who want to use the messaging system
based on Lightning will have to open a channel to big nodes in order to
be able to reach their recipient. In this case, those big nodes can
censor as they want because they have access to a lot of metadata.