docs: add DIP-17 (derivation for Platform payments) and DIP-18 (platform address encodings)

README.md

@@ -2,7 +2,7 @@
 
 DIP stands for Dash Improvement Proposal. Similar to Bitcoin's [BIPs](https://github.com/bitcoin/bips/), a DIP is a design document providing information to the Dash community, or describing a new feature for Dash or its processes or environment. The DIP should provide a concise technical specification of the feature and a rationale for the feature.
 
 Because Dash is forked from the Bitcoin codebase, many of the BIPs can be applied to Dash as well (a list of the BIPs updated to include Dash-specific details can be found [here](https://github.com/dashevo/bips)). The purpose of the DIPs is not to duplicate those which exist as BIPs, but to introduce protocol upgrades or feature specifications which are unique to Dash.
 
 ## Contributions
 
@@ -33,6 +33,8 @@
 [14](dip-0014.md) | Applications | Extended Key Derivation using 256-Bit Unsigned Integers | Samuel Westrich | Informational | Proposed
 [15](dip-0015.md) | Applications | DashPay | Samuel Westrich, Eric Britten | Standard | Proposed
 [16](dip-0016.md) | Applications | Headers First Synchronization on Simple Payment Verification Wallets | Samuel Westrich | Informational | Proposed
+[17](dip-0017.md) | Consensus | Dash Platform Payment Addresses and HD Derivation | Samuel Westrich | Standard | Proposed
+[18](dip-0018.md) | Consensus | Dash Platform Payment Address Encodings | Samuel Westrich, thephez | Standard | Proposed
 [20](dip-0020.md) | Consensus | Dash Opcode Updates | Mart Mangus | Standard | Final
 [21](dip-0021.md) | Consensus | LLMQ DKG Data Sharing | dustinface | Standard | Final
 [22](dip-0022.md) | Consensus | Making InstantSend Deterministic using Quorum Cycles | Samuel Westrich, UdjinM6 | Standard | Final

dip-0009/assignments.md

@@ -9,6 +9,7 @@ Here is a table of current feature paths and any associated DIP. Future DIPs may
 | `5'` | Identity Keys | [DIP 0013: Identities in Hierarchical Deterministic wallets](../dip-0013.md) | The related keys are located in the following sub-paths: <br>`0'/key type'/identity index'/key index'/*` - Identity Authentication ([details](../dip-0013.md#identity-authentication-keys))<br>`1'/*` - Identity Registration Funding ([details](../dip-0013.md#identity-registration-funding-keys))<br>`2'/*` - Identity Topup Funding ([details](../dip-0013.md#identity-top-up-funding-keys))<br>`3'/*` - Identity Invitation Funding ([details](../dip-0013.md#identity-invitatation-funding-keys))<br><br>For example, the first Identity Registration Funding key for Dash would be at `m/9'/5'/5'/1'/0` |
 | `15'` | DashPay - Incoming Funds | [DIP 0015: DashPay](../dip-0015.md#dashpay-incoming-funds-derivation-path) | The related keys are located in the following sub-paths: `/0'/account'/*`<br><br>For example, incoming funds for the first identity would be at `m/9'/5'/15'/0'/*` |
 | `16'` | DashPay - Auto Accept Proof | [DIP 0015: DashPay](../dip-0015.md#auto-accept-proof-autoacceptproof) | The related keys are located in the following sub-paths: `16'/expiration timestamp'`<br><br>For example, the key for a proof expiring at a Unix epoch time of `1605927033` would be at `m/9'/5'/16'/1605927033'` |
+| `17'` | Platform Payment Addresses | [DIP 0017: Dash Platform Payment Addresses and HD Derivation](../dip-0017.md) | The related keys are located in the following sub-paths: `17'/key_class'/index` (default key_class' = `0'`) |
 
 Note: all DIP 0009 paths are of the format: `m / 9' / coin_type' / feature' / *`
 

dip-0017.md

@@ -0,0 +1,185 @@
+<pre>
+  DIP: 0017
+  Title: Dash Platform Payment Addresses and HD Derivation
+  Author(s): Samuel Westrich
+  Special-Thanks: Dash Platform Team
+  Comments-Summary: No comments yet.
+  Status: Draft
+  Type: Standard
+  Created: 2025-11-28
+  License: MIT License
+  Replaces: -
+  Superseded-By: -
+</pre>
+
+## Table of Contents
+
+1. [Abstract](#abstract)
+1. [Motivation](#motivation)
+1. [Prior Work](#prior-work)
+1. [Specification](#specification)
+   1. [Overview](#overview)
+   1. [Derivation Path Definition](#derivation-path-definition)
+   1. [Wallet and Hardware Wallet Behavior](#wallet-and-hardware-wallet-behavior)
+1. [Rationale](#rationale)
+1. [Backwards Compatibility](#backwards-compatibility)
+1. [Reference Implementation](#reference-implementation)
+1. [Security Considerations](#security-considerations)
+1. [Privacy Considerations](#privacy-considerations)
+1. [Test Vectors](#test-vectors)
+1. [DIP-9 Registry Update](#dip-9-registry-update)
+1. [Copyright](#copyright)
+
+## Abstract
+
+This DIP defines Dash Platform payment addresses and their hierarchical deterministic (HD) derivation under [DIP-9](dip-0009.md). It uses Dash coin type 5' on mainnet and coin type 1' on test networks, and introduces a new [DIP-9](dip-0009.md) feature index for Platform payments. The specification standardizes derivation paths (including account separation) and wallet/hardware wallet guidance for Platform payment keys. Address encoding (version bytes and formats) and script-hash address formats are defined in [DIP-18](dip-0018.md).
+
+## Motivation
+
+While Dash Platform identities can hold balances, identity-to-identity payments alone cannot satisfy the requirements for value transfer on Platform. Identities are designed to be persistent, publicly linkable entities with DPNS names and associated documents. Transferring value directly between identities permanently links those identities on-chain, which is undesirable for common payment scenarios and prevents future improvements to privacy and fungibility.
+
+Identity-based transfers also make onboarding unnecessarily complex. Creating a new identity requires funding an asset-lock transaction on the Core chain before the identity can be registered. With a Platform-level payment mechanism, an existing user can send value directly to an address controlled by a new user, allowing that user to create or top up an identity entirely within Platform.
+
+Additionally, many use cases require value that is not tied to a persistent identity—such as one-time payment targets, merchant invoices, or exchange integrations. Platform payment addresses provide this flexibility in a manner analogous to Core-chain addresses.
+
+For these reasons, DIP-17 introduces an address subsystem that complements identity balances and enables direct value transfer, simplified onboarding, improved privacy, and broader application support within Dash Platform. Wallets require an unambiguous address type, network-specific encodings, and deterministic derivation paths that coexist with BIP-44 Core chain funds and existing [DIP-9](dip-0009.md) features (masternodes, identities, DashPay). This DIP defines a single standard so wallets, hardware wallets, and services can implement Platform payments.
+
+## Prior Work
+
+* [DIP-0009: Feature Derivation Paths](https://github.com/dashpay/dips/blob/master/dip-0009.md)
+* [DIP-0013: Identities in Hierarchical Deterministic Wallets](https://github.com/dashpay/dips/blob/master/dip-0013.md)
+* [DIP-0015: DashPay](https://github.com/dashpay/dips/blob/master/dip-0015.md)
+* [BIP-0032: Hierarchical Deterministic Wallets](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki)
+* [BIP-0044: Multi-Account Hierarchy for Deterministic Wallets](https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki)
+
+## Specification
+
+### Overview
+
+Platform payment keys identify recipients of value on Dash Platform. This value includes Dash Credits, which represent DASH held on Platform, as well as other Platform-based payments. These keys are independent of Dash Platform identities and do not belong to an identity’s key set. Instead, they function as standalone payment keys that hold value outside of any identity. They use a single secp256k1 key pair and are not script-based. They are not valid Dash Core chain addresses and MUST NOT be used for Core chain transactions. Their encoding format is specified in [DIP-18](dip-0018.md).
+
+### Derivation Path Definition
+
+The Platform payment feature is assigned [DIP-9](dip-0009.md) feature index `17'`. The canonical derivation path is:
+
+```text
+m / 9' / coin_type' / 17' / account' / key_class' / index
+```
+
+Normative requirements:
+
+* `purpose'` MUST be `9'`.
+* `coin_type'` MUST be `5'` on mainnet (Dash SLIP-44 coin type) and MUST be `1'` on testnet/devnet/regtest (SLIP-44 test coin type), consistent with BIP-44 conventions.
+* `feature'` MUST be `17'` (Platform payment feature).
+* `account'` MUST be hardened. `0'` is the default account. Additional accounts MAY be used following BIP-44-style multi-account semantics.
+* `key_class'` MUST be hardened. The default class for Platform payment receive keys is `0'`. Additional hardened classes MAY be defined by future DIPs; `1'` is reserved for wallet-internal or change-like segregation if a wallet chooses to implement it. Wallets MUST ignore unknown key_class values rather than rejecting the entire account.
+* `index` MUST be non-hardened (`0 ≤ index ≤ 2³¹−1`).
+* No BIP-44 change level is used; privacy is obtained by incrementing `index` and optionally segregating with `key_class'`.
+
+Default account paths:
+
+| Network(s) | Default account path |
+|-|-|
+| Mainnet | `m/9'/5'/17'/0'/0'/index` |
+| Testnet / Devnet / Regtest | `m/9'/1'/17'/0'/0'/index` (coin type `1'` for test networks) |
+
+Wallets MAY derive and expose an extended public key at `m/9'/5'/17'/account'/key_class'` (mainnet) or `m/9'/1'/17'/account'/key_class'` (test networks) for watch-only or monitoring. They MUST NOT expose hardened parent levels.
+
+Accounts follow BIP-44 semantics: `account'` partitions user-controlled sets of Platform payment keys, enabling multiple profiles or organizational separations while preserving hardened isolation between accounts.
+
+### Wallet and Hardware Wallet Behavior
+
+* Wallets MUST derive Platform payment keys only from `m/9'/5'/17'/account'/key_class'/index` (mainnet) or `m/9'/1'/17'/account'/key_class'/index` (test networks). Address encoding of the resulting public keys is specified in [DIP-18](dip-0018.md).
+* Wallets SHOULD clearly separate Platform chain balances from Core chain balances in UI and storage.
+* Wallets SHOULD rotate addresses by incrementing `index` to avoid reuse; a default gap limit of 20 is RECOMMENDED for discovery.
+* Wallets MAY support watch-only by exporting the xpub at `m/9'/5'/17'/account'/key_class'` (mainnet) or `m/9'/1'/17'/account'/key_class'` (test networks).
+* Wallets MAY present multiple accounts following BIP-44 semantics (distinct `account'` values), and SHOULD clearly label the active account in UI.
+* Hardware wallets MUST whitelist the above derivation path and display a label such as “Dash Platform address” when showing or signing.
+* Hardware wallets MUST apply the address encodings defined in [DIP-18](dip-0018.md) and MUST NOT reinterpret these as Core chain P2PKH/P2SH.
+* If a wallet does not implement Platform, it simply never derives the `17'` feature path.
+
+## Rationale
+
+* **Coin type 5' on mainnet, 1' on test networks:** Mainnet keeps Dash SLIP-44 coin type 5', while testnet/devnet/regtest follow SLIP-44 convention with coin type 1'. This avoids new registry allocations and keeps all Dash features under the established namespaces.
+* **DIP-9 vs BIP-44:** DIP-9’s feature level cleanly separates Platform addresses from Core chain funds and from identities/masternodes without overloading BIP-44’s change level or accounts.
+* **Feature index 17':** The next available [DIP-9](dip-0009.md) feature after 16' (DashPay) is reserved for Platform payments, avoiding collisions with existing features.
+* **Hardened upper levels:** `9'/coin_type'/17'/account'/key_class'` isolate Platform keys from other features and from each other. An xpub leak below `key_class'` cannot compromise hardened parents.
+* **Non-hardened leaf index:** Enables watch-only, auditing, and future multisig/shared-custody schemes that rely on unhardened derivation of child public keys. Fully hardened leaves were rejected to preserve these capabilities.
+* **Accounts retained:** A hardened `account'` level maintains BIP-44-style multi-account semantics while still isolating Platform keys under the [DIP-9](dip-0009.md) feature branch.
+* **No BIP-44 change level:** Platform addresses are not UTXO change outputs; a linear `index` (optionally partitioned by `key_class'`) keeps the model simple for hardware wallets and avoids misuse of the 0/1 change bit.
+
+## Backwards Compatibility
+
+* Classic Dash addresses (`X...`, `7...`, `y...`, `8...`) are unaffected. Nodes do not accept Platform addresses in Core chain scripts.
+* DIP-[3](dip-0003.md)/[8](dip-0008.md) masternode derivations and [DIP-13](dip-0013.md) identity derivations remain unchanged.
+* Existing seeds stay valid; wallets can add Platform support without migration.
+* Wallets unaware of Platform will not derive `m/9'/5'/17'/...` and therefore will not interfere with Platform balances.
+
+# Reference Implementation
+
+The following pseudo-code is normative for deriving a Platform payment address:
+
+```text
+function platform_payment_key(seed, account, key_class, index, network):
+    # seed: BIP-39/BIP-32 seed bytes
+    # account: hardened int (default 0)
+    # key_class: hardened int (default 0)
+    # index: non-hardened child number
+    # network: "mainnet" or "testnet"
+
+    coin_type = 5' if network == "mainnet" else 1'
+    path = [9' , coin_type , 17' , account , key_class' , index]
+
+    master_priv, master_chain = bip32_master(seed)  # HMAC-SHA512("Bitcoin seed", seed)
+    child_priv, child_chain = bip32_derive(master_priv, master_chain, path)
+
+    pubkey = secp256k1_compress(secp256k1_point(child_priv))
+    payload = RIPEMD160(SHA256(pubkey))
+
+    return {
+        "private_key": child_priv,
+        "public_key": pubkey,
+        "hash160": payload
+    }
+```
+
+Encoding and decoding of these payloads into addresses is specified in [DIP-18](dip-0018.md).
+
+## Security Considerations
+
+* Derivation uses hardened separation at `feature'` and `key_class'`; compromise of a Platform xpub does not expose other features or other key classes.
+* Leakage of the xpub at `m/9'/coin_type'/17'/account'/key_class'` allows derivation of all Platform public keys for that key class but does not leak private keys or other features.
+* Wallets MUST reject attempts to use Platform addresses in Core chain transactions to prevent misdirected funds.
+* Hardware wallets MUST show the full derivation path and “Dash Platform address” to reduce key-path confusion attacks.
+* The checksum and distinct prefixes mitigate accidental prefix confusion with `X`/`7`/`y`/`8` addresses.
+
+## Privacy Considerations
+
+* Wallets SHOULD avoid address reuse by incrementing `index` and MAY use separate `key_class'` values to segregate user profiles or accounts.
+* Wallets SHOULD avoid correlating Platform `index` progression with Core chain BIP-44 indices to reduce cross-layer linkability.
+* Sharing xpubs at `m/9'/coin_type'/17'/account'/key_class'` enables watch-only but also enables address graph reconstruction for that class; applications should only share when necessary.
+
+## Test Vectors
+
+Mnemonic (test-only): `abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about`  
+Passphrase: `""` (empty)
+
+All hex strings are lowercase, big-endian. Address encodings for the HASH160 values are specified in [DIP-18](dip-0018.md).
+
+| Vector | Path (mainnet / testnet) | account' | key_class' | index | Private Key (hex) | Compressed Pubkey (hex) | HASH160(pubkey) |
+| ------ | ----------------------- | -------- | ---------- | ----- | ----------------- | ----------------------- | --------------- |
+| 1 | m/9'/5'/17'/0'/0'/0 (mainnet) / m/9'/1'/17'/0'/0'/0 (test) | 0' | 0' | 0 | 6bca392f43453b7bc33a9532b69221ce74906a8815281637e0c9d0bee35361fe | 03de102ed1fc43cbdb16af02e294945ffaed8e0595d3072f4c592ae80816e6859e | f7da0a2b5cbd4ff6bb2c4d89b67d2f3ffeec0525 |
+| 2 | m/9'/5'/17'/0'/0'/1 (mainnet) / m/9'/1'/17'/0'/0'/1 (test) | 0' | 0' | 1 | eef58ce73383f63d5062f281ed0c1e192693c170fbc0049662a73e48a1981523 | 02269ff766fcd04184bc314f5385a04498df215ce1e7193cec9a607f69bc8954da | a5ff0046217fd1c7d238e3e146cc5bfd90832a7e |
+| 3 (non-default class) | m/9'/5'/17'/0'/1'/0 (mainnet) / m/9'/1'/17'/0'/1'/0 (test) | 0' | 1' | 0 | cc05b4389712a2e724566914c256217685d781503d7cc05af6642e60260830db | 0317a3ed70c141cffafe00fa8bf458cec119f6fc039a7ba9a6b7303dc65b27bed3 | 6d92674fd64472a3dfcfc3ebcfed7382bf699d7b |
+
+## DIP-9 Registry Update
+
+Reserve [DIP-9](dip-0009.md) feature index `17'` for “Platform Payment Addresses”:
+
+| Feature Index | Feature | DIP | Note |
+| ------------- | ------- | --- | ---- |
+| `17'` | Platform Payment Addresses | DIP-17 | Sub-path: `17'/account'/key_class'/index` (default account' = `0'`, key_class' = `0'`) |
+
+## Copyright
+
+Copyright (c) 2025 Dash Core Group, Inc. [Licensed under the MIT License](https://opensource.org/licenses/MIT)