idnits 2.17.1 draft-dold-payto-14.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (May 01, 2020) is 1418 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Independent Stream F. Dold 3 Internet-Draft Taler Systems SA 4 Intended status: Informational C. Grothoff 5 Expires: November 2, 2020 BFH 6 May 01, 2020 8 The 'payto' URI scheme for payments 9 draft-dold-payto-14 11 Abstract 13 This document defines the 'payto' Uniform Resource Identifier (URI) 14 scheme for designating targets for payments. 16 A unified URI scheme for all payment target types allows applications 17 to offer user interactions with URIs that represent payment targets, 18 simplifying the introduction of new payment systems and applications. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on November 2, 2020. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 1.1. Objective . . . . . . . . . . . . . . . . . . . . . . . . 2 56 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 57 2. Syntax of a 'payto' URI . . . . . . . . . . . . . . . . . . . 3 58 3. Semantics . . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 5. Generic Options . . . . . . . . . . . . . . . . . . . . . . . 4 61 6. Internationalization and Character Encoding . . . . . . . . . 5 62 7. Tracking Payment Target Types . . . . . . . . . . . . . . . . 5 63 7.1. ACH Bank Account . . . . . . . . . . . . . . . . . . . . 6 64 7.2. Business Identifier Code . . . . . . . . . . . . . . . . 7 65 7.3. International Bank Account Number . . . . . . . . . . . . 7 66 7.4. Unified Payments Interface . . . . . . . . . . . . . . . 8 67 7.5. Bitcoin Address . . . . . . . . . . . . . . . . . . . . . 8 68 7.6. Interledger Protocol Address . . . . . . . . . . . . . . 8 69 7.7. Void Payment Target . . . . . . . . . . . . . . . . . . . 9 70 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 71 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 72 9.1. URI Scheme Registration . . . . . . . . . . . . . . . . . 10 73 10. Payment Target Types . . . . . . . . . . . . . . . . . . . . 10 74 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 75 11.1. Normative References . . . . . . . . . . . . . . . . . . 10 76 11.2. Informational References . . . . . . . . . . . . . . . . 11 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 79 1. Introduction 81 This document defines the 'payto' Uniform Resource Identifier (URI) 82 [RFC3986] scheme for designating transfer form data for payments. 84 1.1. Objective 86 A 'payto' URI always identifies the target of a payment. A 'payto' 87 URI consists of a payment target type, a target identifier and 88 optional parameters such as an amount or a payment reference. 90 The interpretation of the target identifier is defined by the payment 91 target type, and typically represents either a bank account or an 92 (unsettled) transaction. 94 A unified URI scheme for all payment target types allows applications 95 to offer user interactions with URIs that represent payment targets, 96 simplifying the introduction of new payment systems and applications. 98 1.2. Requirements Language 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 102 "OPTIONAL" in this document are to be interpreted as described in BCP 103 14 [RFC2119] [RFC8174] when, and only when, they appear in all 104 capitals, as shown here. 106 2. Syntax of a 'payto' URI 108 This document uses the Augmented Backus-Naur Form (ABNF) of 109 [RFC5234]. 111 payto-URI = "payto://" authority path-abempty [ "?" opts ] 112 opts = opt *( "&" opt ) 113 opt-name = generic-opt / authority-specific-opt 114 opt-value = *pchar 115 opt = opt-name "=" opt-value 116 generic-opt = "amount" / "receiver-name" / "sender-name" / 117 "message" / "instruction" 118 authority-specific-opt = ALPHA *( ALPHA / DIGIT / "-" / "." ) 119 authority = ALPHA *( ALPHA / DIGIT / "-" / "." ) 121 'path-abempty' is defined in [RFC3986] in Section 3.3. 'pchar' is 122 defined in [RFC3986], Appendix A. 124 3. Semantics 126 The authority component of a payment URI identifies the payment 127 target type. The payment target types are defined in the "Payment 128 Target Types" sub-registry, see Section 10. The path component of 129 the URI identifies the target for a payment as interpreted by the 130 respective payment target type. The query component of the URI can 131 provide additional parameters for a payment. Every payment target 132 type SHOULD accept the options defined in generic-opt. The default 133 operation of applications that invoke a URI with the payto scheme 134 MUST be to launch an application (if available) associated with the 135 payment target type that can initiate a payment. If multiple 136 handlers are registered for the same payment target type, the user 137 SHOULD be able to choose which application to launch. This allows 138 users with multiple bank accounts (each accessed the respective 139 bank's banking application) to choose which account to pay with. An 140 application SHOULD allow dereferencing a payto URI even if the 141 payment target type of that URI is not registered in the "Payment 142 Target Types" sub-registry. Details of the payment MUST be taken 143 from the path and options given in the URI. The user SHOULD be 144 allowed to modify these details before confirming a payment. 146 4. Examples 148 payto://iban/DE75512108001245126199?amount=EUR:200.0&message=hello 150 INVALID (authority missing): payto:iban/12345 152 5. Generic Options 154 Applications MUST accept URIs with options in any order. The 155 "amount" option MUST NOT occur more than once. Other options MAY be 156 allowed multiple times, with further restrictions depending on the 157 payment target type. The following options SHOULD be understood by 158 every payment target type. 160 amount: The amount to transfer. The format MUST be: 162 amount = currency ":" unit [ "." fraction ] 163 currency = 1*ALPHA 164 unit = 1*(DIGIT / ",") 165 fraction = 1*(DIGIT / ",") 167 If a 3-letter 'currency' is used, it MUST be an [ISO4217] alphabetic 168 code. A payment target type MAY define semantics beyond ISO 4217 for 169 currency codes that are not 3 characters. The 'unit' value MUST be 170 smaller than 2^53. If present, the 'fraction' MUST consist of no 171 more than 8 decimal digits. The use of commas is optional for 172 readability and they MUST be ignored. 174 receiver-name: Name of the entity that receives the payment 175 (creditor). The value of this option MAY be subject to lossy 176 conversion, modification and truncation (for example, due to line 177 wrapping or character set conversion). 179 sender-name: Name of the entity that makes the payment (debtor). The 180 value of this option MAY be subject to lossy conversion, modification 181 and truncation (for example, due to line wrapping or character set 182 conversion). 184 message: A short message to identify the purpose of the payment. The 185 value of this option MAY be subject to lossy conversion, modification 186 and truncation (for example, due to line wrapping or character set 187 conversion). 189 instruction: A short message giving payment reconciliation 190 instructions to the recipient. An instruction that follows the 191 character set and length limitation defined by the respective payment 192 target type SHOULD NOT be subject to lossy conversion. 194 6. Internationalization and Character Encoding 196 Various payment systems use restricted character sets. An 197 application that processes 'payto' URIs MUST convert characters that 198 are not allowed by the respective payment systems into allowable 199 character using either an encoding or a replacement table. This 200 conversion process MAY be lossy, except for the instruction field. 201 If the value of the instruction field would be subject to lossy 202 conversion, modification or truncation, the application SHOULD refuse 203 further processing of the payment until a different value for the 204 instruction is provided. 206 To avoid special encoding rules for the payment target identifier, 207 the userinfo component [RFC3986] is disallowed in payto URIs. 208 Instead, the payment target identifier is given as an option, where 209 encoding rules are uniform for all options. 211 Defining a generic way of tagging the language of option fields 212 containing natural language text (such as "receiver-name", "sender- 213 name" and "message) is out of the scope of this document, as 214 internationalization must accomodate the restrictions and 215 requirements of the underlying banking system of the payment target 216 type. The internationalization concerns SHOULD be individually 217 defined by each payment target type. 219 7. Tracking Payment Target Types 221 A registry of Payment Target Types is described in Section 10. The 222 registration policy for this registry is "First Come First Served", 223 as described in [RFC8126]. When requesting new entries, careful 224 consideration of the following criteria is strongly advised: 226 1. The description clearly defines the syntax and semantics of the 227 payment target and optional parameters if applicable. 229 2. Relevant references are provided if they are available. 231 3. The chosen name is appropriate for the payment target type, does 232 not conflict with well-known payment systems, and avoids 233 potential to confuse users. 235 4. The payment system underlying the payment target type is not 236 fundamentally incompatible with the general options (such as 237 positive decimal amounts) in this specification. 239 5. The payment target type is not a vendor-specific version of a 240 payment target type that could be described more generally by a 241 vendor-neutral payment target type. 243 6. The specification of the new payment target type remains within 244 the scope of payment transfer form data. In particular 245 specifying complete invoices is not in scope. Neither are 246 processing instructions to the payment processor or bank beyond a 247 simple payment. 249 7. The payment target and the options do not contain the payment 250 sender's account details. 252 Documents that support requests for new registry entries should 253 provide the following information for each entry: 255 o Name: The name of the payment target type (case insensitive ASCII 256 string, restricted to alphanumeric characters, dots and dashes) 258 o Description: A description of the payment target type, including 259 the semantics of the path in the URI if applicable. 261 o Example: At least one example URI to illustrate the payment target 262 type. 264 o Contact: The contact information of a person to contact for 265 further information 267 o References: Optionally, references describing the payment target 268 type (such as an RFC) and target-specific options, or references 269 describing the payment system underlying the payment target type. 271 This document populates the registry with six entries as follows (see 272 also Section 10). 274 7.1. ACH Bank Account 276 o Name: ach 278 o Description: Automated Clearing House. The path consist of two 279 components, the routing number and the account number. 280 Limitations on the length and character set of option values are 281 defined by the implementation of the handler. Language tagging 282 and internationalization of options is not supported. 284 o Example: payto://ach/122000661/1234 286 o Contact: N/A 287 o References: [NACHA], [this.I-D] 289 7.2. Business Identifier Code 291 o Name: bic 293 o Description: Business Identifier Code. The path consist of just a 294 BIC. This is used for wire transfers between banks. The registry 295 for BICs is provided by SWIFT. The path does not allow specifying 296 a bank account number. Limitations on the length and character 297 set of option values are defined by the implementation of the 298 handler. Language tagging and internationalization of options is 299 not supported. 301 o Example: payto://bic/SOGEDEFFXXX 303 o Contact: N/A 305 o References: [BIC], [this.I-D] 307 7.3. International Bank Account Number 309 o Name: iban 311 o Description: International Bank Account Number (IBAN). Generally 312 the IBAN allows to unambiguously derive the the associated 313 Business Identifier Code (BIC). However, some legacy applications 314 process payments to the same IBAN differently based on the 315 specified BIC. Thus the path can either consist of a single 316 component (the IBAN) or two components (BIC followed by IBAN). 317 The "message" option of the payto URI corresponds to the 318 "unstructured remittance information" of SEPA credit transfers and 319 is thus limited to 140 characters with character set limitations 320 that differ according to the countries of banks and payment 321 processors involved in the payment. The "instruction" option of 322 the payto URI corresponds to the "end to end identifier" of SEPA 323 credit transfers and is thus limited to at most 35 characters that 324 can be alphanumeric or from the allowed set of special characters 325 "+?/-:().,'". Language tagging and internationalization of 326 options is not supported. 328 o Example: payto://iban/DE75512108001245126199 329 payto://iban/SOGEDEFFXXX/DE75512108001245126199 331 o Contact: N/A 333 o References: [ISO20022], [this.I-D] 335 7.4. Unified Payments Interface 337 o Name: upi 339 o Description: Unified Payment Interface. The path is an account 340 alias. The amount and receiver-name options are mandatory for 341 this payment target. Limitations on the length and character set 342 of option values are defined by the implementation of the handler. 343 Language tags and internationalization of options are not 344 supported. 346 o Example: payto://upi/alice@example.com?receiver- 347 name=Alice&amount=INR:200 349 o Contact: N/A 351 o References: [UPILinking], [this.I-D] 353 7.5. Bitcoin Address 355 o Name: bitcoin 357 o Description: Bitcoin protocol. The path is a "bitcoinaddress" as 358 per [BIP0021]. Limitations on the length and character set of 359 option values are defined by the implementation of the handler. 360 Language tags and internationalization of options are not 361 supported. 363 o Example: payto://bitcoin/12A1MyfXbW6RhdRAZEqofac5jCQQjwEPBu 365 o Contact: N/A 367 o References: [BIP0021], [this.I-D] 369 7.6. Interledger Protocol Address 371 o Name: ilp 373 o Description: Interledger protocol. The path is an ILP address as 374 per [ILP-ADDR]. Limitations on the length and character set of 375 option values are defined by the implementation of the handler. 376 Language tagging and internationalization of options is not 377 supported. 379 o Example: payto://ilp/g.acme.bob 381 o Contact: N/A 382 o References: [ILP-ADDR], [this.I-D] 384 7.7. Void Payment Target 386 o Name: void 388 o Description: The "void" payment target type allows specifying the 389 parameters of an out-of-band payment (such as cash or other types 390 of in-person transactions). The path is optional and interpreted 391 as a comment. Limitations on the length and character set of 392 option values are defined by the implementation of the handler. 393 Language tags and internationalization of options are not 394 supported. 396 o Example: payto://void/?amount=EUR:10.5 398 o Contact: N/A 400 o References: [this.I-D] 402 8. Security Considerations 404 Interactive applications handling the payto URI scheme MUST NOT 405 initiate any financial transactions without prior review and 406 confirmation from the user, and MUST take measures to prevent 407 clickjacking [HMW12]. 409 Unless a payto URI is received over a trusted, authenticated channel, 410 a user might not be able to identify the target of a payment. In 411 particular due to homographs [unicode-tr36], a payment target type 412 SHOULD NOT use human-readable names in combination with unicode in 413 the target account specification, as it could give the user the 414 illusion of being able to identify the target account from the URI. 416 The authentication/authorization mechanisms and transport security 417 services used to process a payment encoded in a payto URI are handled 418 by the application and are not in scope of this document. 420 To avoid unnecessary data collection, payment target types SHOULD NOT 421 include personally identifying information about the sender of a 422 payment that is not essential for an application to conduct a 423 payment. 425 9. IANA Considerations 427 IANA maintains a registry called the "Uniform Resource Identifier 428 (URI) Schemes" registry. 430 9.1. URI Scheme Registration 432 IANA maintains the "Uniform Resource Identifier (URI) Schemes" 433 registry that contains an entry for the 'payto' URI scheme. IANA is 434 requested to update that entry to reference this document when 435 published as an RFC. 437 10. Payment Target Types 439 This document specifies a list of Payment Target Types. It is 440 possible that future work will need to specify additional payment 441 target types. The GNUnet Assigned Numbers Authority (GANA) [GANA] 442 operates the "payto-payment-target-types" registry to track the 443 following information for each payment target type: 445 o Name: The name of the payment target type (case insensitive ASCII 446 string, restricted to alphanumeric characters, dots and dashes) 448 o Contact: The contact information of a person to contact for 449 further information 451 o References: Optionally, references describing the payment target 452 type (such as an RFC) and target-specific options, or references 453 describing the payment system underlying the payment target type. 455 The entries that have been made for the "payto-payment-target-types" 456 defined in this document are as follows: 458 Name | Contact | Reference 459 ----------+-------------------------+------------ 460 ach | N/A | [This.I-D] 461 bic | N/A | [This.I-D] 462 iban | N/A | [This.I-D] 463 upi | N/A | [This.I-D] 464 bitcoin | N/A | [This.I-D] 465 ilp | N/A | [This.I-D] 466 void | N/A | [This.I-D] 468 11. References 470 11.1. Normative References 472 [ISO20022] 473 International Organization for Standardization, "ISO 20022 474 Financial Services - Universal financial industry message 475 scheme", May 2013. 477 [ISO4217] International Organization for Standardization, "ISO 4217 478 Currency Codes", August 2018. 480 [NACHA] NACHA, "NACHA Operating Rules & Guidelines", January 2017. 482 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 483 Requirement Levels", BCP 14, RFC 2119, 484 DOI 10.17487/RFC2119, March 1997, 485 . 487 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 488 Resource Identifier (URI): Generic Syntax", STD 66, 489 RFC 3986, DOI 10.17487/RFC3986, January 2005, 490 . 492 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 493 Specifications: ABNF", STD 68, RFC 5234, 494 DOI 10.17487/RFC5234, January 2008, 495 . 497 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 498 Writing an IANA Considerations Section in RFCs", BCP 26, 499 RFC 8126, DOI 10.17487/RFC8126, June 2017, 500 . 502 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 503 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 504 May 2017, . 506 [unicode-tr36] 507 Davis, M., Ed. and M. Suignard, "Unicode Technical Report 508 #36: Unicode Security Considerations", September 2014. 510 11.2. Informational References 512 [BIC] International Organization for Standardization, "ISO 513 9362:2014 Business Identifier Code (BIC)", March 2019, 514 . 516 [BIP0021] Schneider, N. and M. Corallo, "Bitcoin Improvement 517 Proposal 21", January 2012, 518 . 520 [GANA] GNUnet e.V., "GNUnet Assigned Numbers Authority (GANA)", 521 April 2020, . 523 [HMW12] Huang, L., Moshchuk, A., Wang, H., Schecter, S., and C. 524 Jackson, "Clickjacking: Attacks and Defenses", January 525 2012, . 528 [ILP-ADDR] 529 Interledger Team, "ILP Addresses - v2.0.0", September 530 2018, . 532 [UPILinking] 533 National Payment Corporation of India, "Unified Payment 534 Interface - Common URL Specifications For Deep Linking And 535 Proximity Integration", November 2017, 536 . 539 Authors' Addresses 541 Florian Dold 542 Taler Systems SA 543 7, rue de Mondorf 544 Erpeldange L-5421 545 LU 547 Email: dold@taler.net 549 Christian Grothoff 550 BFH 551 Hoeheweg 80 552 Biel/Bienne CH-2501 553 CH 555 Email: christian.grothoff@bfh.ch