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125 lines
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125 lines
6.5 KiB
Plaintext
<pre>
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BIP: 21
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Title: URI Scheme
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Author: Nils Schneider <nils.schneider@gmail.com>
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Matt Corallo <bip21@bluematt.me>
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Status: Accepted
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Type: Standards Track
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Created: 2012-01-29
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</pre>
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This BIP is a modification of an earlier [[bip-0020.mediawiki|BIP 0020]] by Luke Dashjr. BIP 0020 was based off an earlier document by Nils Schneider. The alternative payment amounts in BIP 0020 have been removed.
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==Abstract==
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This BIP proposes a URI scheme for making Bitcoin payments.
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==Motivation==
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The purpose of this URI scheme is to enable users to easily make payments by simply clicking links on webpages or scanning QR Codes.
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==Specification==
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=== General rules for handling (important!) ===
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Bitcoin clients MUST NOT act on URIs without getting the user's authorization.
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They SHOULD require the user to manually approve each payment individually, though in some cases they MAY allow the user to automatically make this decision.
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=== Operating system integration ===
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Graphical bitcoin clients SHOULD register themselves as the handler for the "bitcoin:" URI scheme by default, if no other handler is already registered. If there is already a registered handler, they MAY prompt the user to change it once when they first run the client.
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=== General Format ===
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Bitcoin URIs follow the general format for URIs as set forth in RFC 3986. The path component consists of a bitcoin address, and the query component provides additional payment options.
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Elements of the query component may contain characters outside the valid range. These must first be encoded according to UTF-8, and then each octet of the corresponding UTF-8 sequence must be percent-encoded as described in RFC 3986.
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=== ABNF grammar ===
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(See also [[#Simpler syntax|a simpler representation of syntax]])
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bitcoinurn = "bitcoin:" bitcoinaddress [ "?" bitcoinparams ]
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bitcoinaddress = *base58
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bitcoinparams = bitcoinparam [ "&" bitcoinparams ]
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bitcoinparam = [ amountparam / labelparam / messageparam / otherparam / reqparam ]
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amountparam = "amount=" *digit [ "." *digit ]
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labelparam = "label=" *qchar
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messageparam = "message=" *qchar
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otherparam = qchar *qchar [ "=" *qchar ]
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reqparam = "req-" qchar *qchar [ "=" *qchar ]
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Here, "qchar" corresponds to valid characters of an RFC 3986 URI query component, excluding the "=" and "&" characters, which this BIP takes as separators.
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The scheme component ("bitcoin:") is case-insensitive, and implementations must accept any combination of uppercase and lowercase letters. The rest of the URI is case-sensitive, including the query parameter keys.
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=== Query Keys ===
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*label: Label for that address (e.g. name of receiver)
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*address: bitcoin address
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*message: message that describes the transaction to the user ([[#Examples|see examples below]])
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*size: amount of base bitcoin units ([[#Transfer amount/size|see below]])
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*(others): optional, for future extensions
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==== Transfer amount/size ====
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If an amount is provided, it MUST be specified in decimal BTC.
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All amounts MUST contain no commas and use a period (.) as the separating character to separate whole numbers and decimal fractions.
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I.e. amount=50.00 or amount=50 is treated as 50 BTC, and amount=50,000.00 is invalid.
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Bitcoin clients MAY display the amount in any format that is not intended to deceive the user.
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They SHOULD choose a format that is foremost least confusing, and only after that most reasonable given the amount requested.
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For example, so long as the majority of users work in BTC units, values should always be displayed in BTC by default, even if mBTC or TBC would otherwise be a more logical interpretation of the amount.
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== Rationale ==
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===Payment identifiers, not person identifiers===
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Current best practices are that a unique address should be used for every transaction.
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Therefore, a URI scheme should not represent an exchange of personal information, but a one-time payment.
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===Accessibility (URI scheme name)===
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Should someone from the outside happen to see such a URI, the URI scheme name already gives a description.
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A quick search should then do the rest to help them find the resources needed to make their payment.
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Other proposed names sound much more cryptic; the chance that someone googles that out of curiosity are much slimmer.
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Also, very likely, what he will find are mostly technical specifications - not the best introduction to bitcoin.
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==Forward compatibility==
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Variables which are prefixed with a req- are considered required. If a client does not implement any variables which are prefixed with req-, it MUST consider the entire URI invalid. Any other variables which are not implemented, but which are not prefixed with a req-, can be safely ignored.
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==Backward compatibility==
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As this BIP is written, several clients already implement a bitcoin: URI scheme similar to this one, however usually without the additional "req-" prefix requirement. Thus, it is recommended that additional variables prefixed with req- not be used in a mission-critical way until a grace period of 6 months from the finalization of this BIP has passed in order to allow client developers to release new versions, and users of old clients to upgrade.
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== Appendix ==
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=== Simpler syntax ===
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This section is non-normative and does not cover all possible syntax.
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Please see the BNF grammar above for the normative syntax.
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[foo] means optional, <bar> are placeholders
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<nowiki>bitcoin:<address>[?amount=<amount>][?label=<label>][?message=<message>]</nowiki>
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=== Examples ===
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Just the address:
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bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W
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Address with name:
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bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?label=Luke-Jr
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Request 20.30 BTC to "Luke-Jr":
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bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?amount=20.3&label=Luke-Jr
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Request 50 BTC with message:
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bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?amount=50&label=Luke-Jr&message=Donation%20for%20project%20xyz
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Some future version that has variables which are (currently) not understood and required and thus invalid:
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bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?req-somethingyoudontunderstand=50&req-somethingelseyoudontget=999
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Some future version that has variables which are (currently) not understood but not required and thus valid:
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bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?somethingyoudontunderstand=50&somethingelseyoudontget=999
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Characters must be URI encoded properly.
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== Reference Implementations ==
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=== Bitcoin clients ===
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* Bitcoin-Qt supports the old version of Bitcoin URIs (ie without the req- prefix), with Windows and KDE integration as of commit 70f55355e29c8e45b607e782c5d76609d23cc858.
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