Merge pull request #391 from ImranLorgat/patch-18

Presentation Layer - What information does an invoice contain?

e2e-presentation-layer.asciidoc

@@ -11,6 +11,69 @@ Relevant questions to answer:
     * keysend
     * custom data
 
+
+=== What information does an invoice contain?
+
+A Lightning Network invoice is a request for payment issued by the receiver and contains all the information the sender needs to successfully execute the payment.
+Usually it will be in the form of a QR code or an alphanumeric string that looks something like this:
+
+_lnbc9150n1p05hx8upp5ug254f9nhymhu2kctm5j9qq28pvvfsqrdaj6fnxzhln023vyka6sdzz2pshjmt9de6zqen0wgsrjvf4ypcxj7r9d3ejqct5ypekzar0wd5xjuewwpkxzcm99cxqzjccqp2sp5k8nxp5jy26c00ny8asampc03z2edl3z784d80hz873g4jkkuqtvqrzjqgmkp5859l5tn0h6rlal5d44vlkl9r6hf03v6e3pnumr96rak85jqztsugqqkvcqqqqqqquyqqqqqqgq9q9qy9qsqwar8ak9hh4cu3evy6z0nzwpq7ax6mdums6utatejnzak78a9vfyq4ya9gnwsquaq5e257qc3fw2tdxqyk2k9fzgmldfd3urskyuzxmqpyy8tke_
+
+Invoice encoding and decoding is defined by BOLT #11
+footnote:[BOLT11 Github: https://github.com/lightningnetwork/lightning-rfc/blob/master/11-payment-encoding.md].
+The above string is composed of two sections, split by a seperator.
+
+The first part, _lnbc9150n_, is the human-readable part of the invoice.
+The _lnbc_ tells us that the invoice is for Lightning Network Bitcoin
+(it could be for Lightning Testnet or a different cryptocurrency).
+The _9150n_ tells us the invoice is for 915 satoshis (expressed here as 91500 millisatoshis).
+The last _1_ character in the string indicates the end of the human-readable section.
+
+Everything after the _1_ is the data part and contains the following information:
+
+* *Destination*: the ID of the node receiving the payment.
+* *Timestamp*: the date and time the invoice was created, measured in seconds past since 1970.
+* *Payment Hash*: the hash of the payment pre-image. Pre-images were discussed in the earlier chapter on Routing.
+* *Expiry Time*: the amount of time, in seconds, after which the invoice expires and can no longer be paid.
+* *CLTV Delta*: the delta to be used in the final HTLC in the path. Discussed in the earlier chapter on Routing.
+* *Signature*: a digital signature by the invoice issuer. If anything in the invoice is changed, the signature check will fail and the invoice will no longer be valid. This prevents attackers tampering with invoices.
+* _(Optional)_ *Description*: a human-readable explanation of what the payment is for.
+* _(Optional)_ *Backup Bitcoin Address*: an on-chain payment address in case payment of the invoice fails.
+* _(Optional)_ *Routing Hints*: to assist the payer in finding a path for the payment. Discussed in the earlier chapter on Path Finding.
+
+An invoice also contains other useful information.
+In the next section, we'll break down the above invoice and identify each individual part.
+
+
+==== Anatomy of a Lightning Invoice
+
+If we enter the above invoice into a invoice decoding tool, such as https://lndecode.com/, we get the following output:
+
+* *Network*: bitcoin mainnet
+* *Amount*: 0.00000915 BTC
+* *Date*: Sun, 30 Aug 2020 12:18:04 GMT
+* *Payment Hash*: e2154aa4b3b9377e2ad85ee922800a3858c4c0036f65a4ccc2bfe6f54584b775
+* *Description*: Payment for 915 pixels at satoshis.place.
+* *Expiration Time*: 600 seconds
+* *Min Final CLTV Expiry*: 10
+* *Payment Secret*: b1e660d24456b0f7cc87ec3bb0e1f112b2dfc45e3d5a77dc47f451595adc02d8
+* *Routing Info*:
+** _Public Key_: 023760d0f42fe8b9befa1ffbfa36b567edf28f574be2cd66219f3632e87db1e920
+** _Short Channel Id_: 0970e2000b330000
+** _Fee Base Msat_: 900
+** _Fee Proportional Millimonths_: 1
+** _CLTV Expiry Delta_: 40
+* *Feature Bits*: 00101000001000000000
+* *Signature*:
+** _R value_: 77467ed8b7bd71c8e584d09f313820f74dadb79b86b8beaf3298bb6f1fa56248
+** _S value_: 0a93a544dd0073a0a6554f03114b94b69804b2ac54891bfb52d8f070b138236c
+** _Recovery Flag_: 1
+* *Signing Data*: 6c6e6263393135306e0be9731f810d388552a92cee4ddf8ab617ba48a0028e16313000dbd9693330aff9bd51612ddd41a212830bcb6b2b73a103337b9101c989a903834bc32b6399030ba1039b0ba37b9b434b997383630b1b2970600a58c002a806963ccc1a488ad61ef990fd87761c3e22565bf88bc7ab4efb88fe8a2b2b5b805b00314808dd8343d0bfa2e6fbe87fefe8dad59fb7ca3d5d2f8b3598867cd8cba1f6c7a48025c388002ccc000000000e100000000400a02808504000
+* *Checksum*: yy8tke
+
+
+
+
 === What are some unique things that can be done with LN?
 
 **Micropayments**: The current financial system in most countries is divisible to a certain extent and not lower (E.g. $1 = 100c).