72/WAKU-RLN-KEYSTORE: add new RFC

content/docs/rfcs/72/README.md

@@ -0,0 +1,301 @@
+---
+slug: 72
+title: 72/WAKU-RLN-KEYSTORE
+name: Waku RLN Keystore
+status: raw
+category: Standards Track
+editor: Jimmy Debe <jimmy@status.im>
+contributors: 
+- Aaryamann Challani <aaryamann@status.im>
+---
+
+# Abstract
+This specification describes how RLN, Rate Limit Nullifier, 
+credentials are securely stored in a JSON schema.
+
+# Summary
+A keystore is a construct to store a user’s keys. 
+The keys will be encrypted and decrypted based on methods specified in this specification. 
+The keystore stores a user's credentials locally and
+uses [32/RLN-V1](/spec/32/) as a spam-prevention mechanism by generating zero-knowledge proofs.
+
+# Background
+The secure storage of keys is important in peer-to-peer messaging applications.
+A `72/WAKU-RLN-KEYSTORE` uses zero-knowledge proofs for anonymous rate-limiting for messaging frameworks. 
+Generated credentials by a user are encrypted and stored in the keystore to be retrieved over a network.
+With [32/RLN-V1](/spec/32/), sending and receiving 
+messages will ensure a message rate for a network is being followed while preserving the anonymity of the message owner. 
+
+## Waku RLN Keystore Format:
+
+A format example of a keystore used by a [17/WAKU2-RLN-Relay](/spec/17/).
+
+```js
+const Keystore {
+	application: "waku-rln-relay" ,
+	appIdentifier: "string",
+	version: "string",
+	credentials: {
+    		"membershipHash": {
+      			crypto: {
+        			cipher: "string",
+        			cipherparams: {
+					iv: "string",
+				},
+        			ciphertext: "string",
+        			kdf: "string",
+        			kdfparams: {
+          				dklen: integer,
+          				c: integer,
+          				prf: "string",
+          				salt: "string",
+        			},
+        			mac: "string",
+      			}
+    		}
+	}
+}
+
+```
+
+# Specification
+The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, 
+“NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in [RFC 2119](https://www.ietf.org/rfc/rfc2119.txt).
+
+The keystore MUST be generated by a cryptographic construction with password verification and decryption.
+
+Keystore modules MUST include metadata, key derivation function, checksum, cipher, and a membership hash.
+
+## Metadata:
+Information about the keystore SHOULD be stored in the metadata.
+
+The declaration of `application`, `version`, and `appIdentifier` COULD occur in the metadata.
+
+- `application` : current application, MUST be a string
+- `version` : application version, MUST be a string
+- `appIdentifier`: application identifier, MUST be a string
+
+## Credentials:
+
+After RLN credentials are generated, it MUST be stored in a JSON schema.
+The Waku RLN credentials MUST consist of a `membershipHash` and `WakuCredential`.
+The `membershipHash` will be an identity hash of the user.
+The `WakuCredential` will store to encryption portion of the keystore.
+There COULD be multiple credentials stored in a keystore, categorized by the `membershipHash`.
+
+Each contruct MUST include the keypair:
+> key: [`membershipHash`]: pair: [`WakuCredential`]
+
+### membershipHash 
+
+The `membershipHash` SHOULD be generated by user's participating in a membership group.
+Each user SHOULD register to the group with an `identity_commitment` stored in a Merkle tree.
+A cryptographic hash function that SHOULD be used to generate the `membershipHash` is [SHA256](https://www.rfc-editor.org/rfc/rfc4634.txt).
+The hash function that is used,
+SHOULD be mentioned in the `verison` attribute.
+To generate the `membershipHash`, 
+the `treeIndex`, `membershipContract`, `contractId` and `identityCredential` attributes SHOULD be used to create a hexadecimal string.
+- it MUST NOT already exist in the keystore.
+
+#### treeIndex
+
+After a user registers to a group, 
+a `treeIndex` value of the position in the Merkle tree SHOULD be returned.
+- it MUST be a Merkle tree data structure filled with `identity_commitment` from user registrations.
+- it MUST be a hexadecimal string
+
+#### membershipContract
+
+For decentralized membership registrations, 
+the `membershipContract` SHOULD be derived from a public blockchain using smart contracts. 
+- it MUST be a hash of a `contractAddress`
+- `contractAddess` MUST be a string.
+
+#### contractId
+
+The `contractId` SHOULD be the blockchain identifier used for `membershipcontract`.
+- it MUST be a string
+
+#### identityCredential
+
+The `identityCredential` MUST be derived after a succussful decryption of the keystore.
+
+The `identityCredential` MUST be constructed with the `identity_secret`, `identity_secret_hash`, `identity_commitment` values.
+- it MUST be a hash of `identity_commitment` stored in a Merkle tree.
+- it MUST be a string.
+
+##### `identity_secret`
+
+The `identity_secret` MUST be constructed with `identity_nullifier` + `identity_trapdoor` values. 
+- `identity_nullifier` : Random 32 byte value
+- `identity_trapdoor` : Random 32 byte value
+
+##### `identity_secret_hash` 
+
+Used to derive the `identity_commitment` of the user, and 
+as a private input for zero-knowledge proof generation.
+- it MUST be created with `identity_secret` as a parameter for the hash function.
+- This secret hash SHOULD be kept private by the user.
+
+##### `identity_commitment` 
+- it MUST be created with `identity_secret_hash` by using hashing function as described in [Poseidon Paper](https://eprint.iacr.org/2019/458.pdf). 
+- it MUST be used by a user for group registering.
+
+### `WakuCredential`
+
+The `WakuCredential` will store values used for encrytion and decrypting user's credentials.
+- it MUST be used for password verification.
+- it MUST follow [EIP-2335](https://eips.ethereum.org/EIPS/eip-2335) 
+
+### KDF
+
+The password-based encryption used SHOULD be KDF, key derivation function, 
+to produce a derived key from a password and other parameters.
+The keystore COULD use PBKDF2 password-based encryption, 
+as described in [RFC 2898](https://www.ietf.org/rfc/rfc2898.txt).
+
+A `WakuCredential` object MUST include:
+| Name | Description  |
+|----|-----|
+| password | used to encrypt keystore and decryption key |
+| secret | key to be encrypted |
+| pubKey | public key |
+| path | HD, hardened derivation, path used to generate the secret |
+| checksum | hashing function | 
+| cipher | cipher function |
+
+```js
+
+crypto: {
+
+	cipher: "string" // The cipher function
+	cipherparams: {
+		iv: "string" // The cipher parameters
+	},
+	ciphertext: "string" // The cipher message,
+	kdf: "string" // KDF Function,
+	kdfparams: {
+		param: integer // Salt value and iteration count,
+		dklen: integer // Length in octets of derived key, MUST be positive integer,
+		c: "string" // Iteration count, MUST be positive integer,
+		prf: "string" // Underlying pseudorandom function,
+		salt: "string" // Produces a large set of keys based on the password
+	},
+	mac: "string" // Checksum
+}
+
+```
+
+### Decryption
+The keystore SHOULD decrypt a user's credentials using a password and 
+a Merkle proof, the `membershipHASh`, using PBKDF2 that returns the `decryptionKey` key.
+The decryption key is used to verify the keystore is correct.
+- To generate the `decryptionKey`, it MUST be constructed from a password and KDF,
+as desrcibed in [ERC-2335: BLS12-381 Keystore](https://eips.ethereum.org/EIPS/eip-2335).
+- The `decryptionKey`, is derived from the cipher function and
+cipher parameters described in the KDF used in the keystore.
+
+## Test Vectors
+### Input:
+Hashing function used: Poseidon Hash, as described in [Poseidon Paper](https://eprint.iacr.org/2019/458.pdf)
+
+`application`: "waku-rln-relay"
+
+`appIdentifier`: "01234567890abcdef"
+
+`version`: "0.2" 
+
+`hashFunction`: "poseidonHash"
+
+`password`: "sup3rsecure"
+
+
+
+```js
+
+identityCredential = {
+	IDTrapdoor: [
+		211, 23, 66, 42, 179, 130, 131, 111, 201, 205, 244, 34, 27, 238, 244,
+        	216, 131, 240, 188, 45, 193, 172, 4, 168, 225, 225, 43, 197, 114, 176,
+        	126, 9,
+	],
+	IDNullifier: [
+        	238, 168, 239, 65, 73, 63, 105, 19, 132, 62, 213, 205, 191, 255, 209, 9,
+        	178, 155, 239, 201, 131, 125, 233, 136, 246, 217, 9, 237, 55, 89, 81,
+        	42,
+	],
+	IDSecretHash: [
+        	150, 54, 194, 28, 18, 216, 138, 253, 95, 139, 120, 109, 98, 129, 146,
+        	101, 41, 194, 36, 36, 96, 152, 152, 89, 151, 160, 118, 15, 222, 124,
+        	187, 4,
+	],
+	IDCommitment: [
+        	112, 216, 27, 89, 188, 135, 203, 19, 168, 211, 117, 13, 231, 135, 229,
+		58, 94, 20, 246, 8, 33, 65, 238, 37, 112, 97, 65, 241, 255, 93, 171, 15,
+	],
+
+}
+
+membership = {
+      chainId: "0xAA36A7",
+      treeIndex: 8,
+      address: "0x8e1F3742B987d8BA376c0CBbD7357fE1F003ED71",
+}
+
+```
+
+### Output:
+
+```js
+application: "waku-rln-relay",
+appIdentifier: "01234567890abcdef",
+version: "0.2",
+  credentials: {
+    "9DB2B4718A97485B9F70F68D1CC19F4E10F0B4CE943418838E94956CB8E57548": {
+      crypto: {
+        cipher: "aes-128-ctr",
+        cipherparams: {
+          iv: "fd6b39eb71d44c59f6bf5ff3d8945c80",
+        },
+        ciphertext:     "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",
+        kdf: "pbkdf2",
+        kdfparams: {
+          dklen: 32,
+          c: 1000000,
+          prf: "hmac-sha256",
+          salt: "60f0aa92fbf63a8356dfdbed2ab18058",
+        },
+        mac: "51a227ac6db7f2797c63925880b3db664e034231a4c68daa919ab42d8df38bc6",
+      },
+    }
+
+
+```
+
+# Security Considerations
+### 1.) Add a Password
+
+An attacker can identify which credential belongs to a combination of `chainId` and 
+`contractAddress` pair by brute forcing the `treeIndex` iteratively to find a hash match.
+The RECOMMENDED solution is to add a password to the construction of `membershipHash` to prevent this attack.
+
+The RECOMMENDED `membershipHash` Construction:
+- `membershipHash` SHOULD be constructed with `treeIndex`, `membershipContract`, `identityCredential`, `membershipPassword`
+	- `membershipPassword` : a new password created to private attacks compromising keystore credentials.
+ - The user MUST store the `membershipPassword` privately.
+
+# Copyright
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
+
+# References
+1. [32/RLN-V1](/spec/32/)
+2. [17/WAKU2-RLN-RELAY](/spec/17/)
+3. [RFC 2119](https://datatracker.ietf.org/doc/html/rfc2119)
+4. [RFC 8174](https://datatracker.ietf.org/doc/html/rfc8174)
+5. [EIP-2335](https://eips.ethereum.org/EIPS/eip-2335)
+6. [RFC 2898](https://www.ietf.org/rfc/rfc2898.txt)
+7. [ERC-2335: BLS12-381 Keystore](https://eips.ethereum.org/EIPS/eip-2335)
+8. [Poseidon Paper](https://eprint.iacr.org/2019/458.pdf)
+
+
+

content/menu/index.md

@@ -29,6 +29,7 @@ bookMenuLevels: 1
   - [66/WAKU2-METADATA]({{< relref "/docs/rfcs/66/README.md" >}})
   - [70/ETH-SECPM]({{< relref "/docs/rfcs/70/README.md" >}})
   - [71/STATUS-PUSH-NOTIFICATION-SERVER]({{< relref "/docs/rfcs/71/README.md" >}})
+  - [72/WAKU-RLN-KEYSTORE]({{< relref "/docs/rfcs/72/README.md" >}})
 - Draft
   - [1/COSS]({{< relref "/docs/rfcs/1/README.md" >}})
   - [3/REMOTE-LOG]({{< relref "/docs/rfcs/3/README.md" >}})