This specification describes a protocol for communication between a merchant and their customer, enabling both a better customer experience and better security against man-in-the-middle attacks on the payment process.
This payment protocol is an extension of BIP 70, BIP 71, BIP 72, and the Simple Ledger Protocol URI Scheme Specification. Applications which support these protocols are able, with minor modifications, to support the payment protocol described in this specification.
Payment Requests are generated according to the BIP 70 specification with the following additional requirements:
- Outputs must be in the proper order according to the Simple Ledger Token specification
- The first output in the Payment Request (vout=0) must be the SLP OP_RETURN output
- All outputs listed in the SLP OP_RETURN output must have a corresponding output in the Payment Request (vout=1-n)
- The transaction defined by the Payment Request must conform to the specification for a SEND transaction of SLP Token Type 1
Payments are generated according to the BIP 70 specification with the following additional considerations:
- Outputs in the transaction must be listed in the exact order prescribed by the Payment Request
- Additional outputs, such as those for sending change, may be appended to the SLP OP_RETURN script at index 0
Payments are considered valid if the submitted transaction has the outputs required by the Payment Request. As with BIP 70, the script and amount for all required outputs, except the output at index 0, must match the details in the Payment Request. The SLP OP_RETURN script (vout=0) does not have to exactly match the script in the Payment Request to be considered valid. However, it must include any requested outputs.
SLP Token Type 2 specification allows for multi-output MINT transactions. As this allows for a broad variety of MINT transactions that can satisfy a payment request, and because there is no difference in value between a MINT output and a SEND output, MINT transactions that otherwise satisfy the requirements of the Payment Request are considered valid, even if the request is for a SEND transaction.
REQUESTED SCRIPT (ASM):
OP_RETURN 534c5000 OP_1 53454e44 4de69e374a8ed21cbddd47f2338cc0f479dc58daa2bbe11cd604ca488eca0ddf 000000000000000a 0000000000000014 000000000000000a
VALID SCRIPT (ASM) - APPENDED CHANGE OUTPUT:
OP_RETURN 534c5000 OP_1 53454e44 4de69e374a8ed21cbddd47f2338cc0f479dc58daa2bbe11cd604ca488eca0ddf 000000000000000a 0000000000000014 000000000000000a 00000002540be400
INVALID SCRIPT (ASM) - MISSING REQUIRED OUTPUT:
OP_RETURN 534c5000 OP_1 53454e44 4de69e374a8ed21cbddd47f2338cc0f479dc58daa2bbe11cd604ca488eca0ddf 000000000000000a 0000000000000014
TOKEN TYPE 2 REQUESTED SEND SCRIPT (ASM):
OP_RETURN 534c5000 OP_2 53454e44 4de69e374a8ed21cbddd47f2338cc0f479dc58daa2bbe11cd604ca488eca0ddf 000000000000000a 0000000000000014 000000000000000a
VALID SCRIPT (ASM) - TOKEN TYPE 2 MINT WITH REQUIRED OUTPUTS:
OP_RETURN 534c5000 OP_2 4d494e54 4de69e374a8ed21cbddd47f2338cc0f479dc58daa2bbe11cd604ca488eca0ddf 000000000000000a 0000000000000014 000000000000000a
VALID SCRIPT (ASM) - TOKEN TYPE 2 MINT WITH REQUIRED OUTPUTS + ADDITIONAL OUTPUT:
OP_RETURN 534c5000 OP_2 4d494e54 4de69e374a8ed21cbddd47f2338cc0f479dc58daa2bbe11cd604ca488eca0ddf 000000000000000a 0000000000000014 000000000000000a 00000002540be400
The URI scheme follows BIP 72, and the Simple Ledger Protocol URI Scheme Specification.
A backwards-compatible request:
simpleledger:qqmtw4c35mpv5rcjnnsrskpxvzajyq3f9ygldn8fj0?amount1=10.0001-<xyzTokenID>&label=Satoshi-Nakamoto&r=https://merchant.com/pay/3D2a8628fc2fbe
Non-backwards-compatible equivalent:
simpleledger:?r=https://merchant.com/pay/3D2a8628fc2fbe
The MIME (RFC 2046) Media Types follow the basic specification described in BIP 71. The Media Type (Content-Type in HTML/email headers) for messages shall be:
| Message | Type/Subtype |
|---|---|
| PaymentRequest | application/simpleledger-paymentrequest |
| Payment | application/simpleledger-payment |
| PaymentACK | application/simpleledger-paymentack |
A web server generating a PaymentRequest message to initiate the payment protocol would precede the binary message data with the following headers:
Content-Type: application/simpleledger-paymentrequest
Accept: application/simpleledger-payment
Content-Transfer-Encoding: binary
None currently