miniscript: add proto messages

We will support miniscript as part of output descriptors.

Descriptors are an expression language to specify Bitcoin outputs. For
example, `wsh(multi(2,<pubkey1>,<pubkey2>,<pubkey3>))` is a 2-of-3
multisig wrapped in a P2WSH (pay-to-witness-script-hash) output.
Descriptors specification: https://github.com/bitcoin/bitcoin/blob/8f402710371a40c5777dc3f9c4ba6ca8505a2f90/doc/descriptors.md

In fragments wrapping SCRIPT expressions, SCRIPT can also be a
miniscript expression, for example: `wsh(or_b(pk(<pubkey1>),s:pk(<pubkey2>)))`.

With hardware signers, we want to use xpubs with derivations instead
of raw pubkeys, and also have a shorter representation than inlining
the xpubs for readability. That is why we will follow the 'Wallet
Policies for Descriptor Wallets' proposal specied here:

https://github.com/bigspider/bips/blob/bip-wallet-policies/bip-wallet-policies.mediawiki (bitcoin/bips#1389).

The above example then become `wsh(or_b(pk(@0/**),s:pk(@1/**)))`. The
`@NUM` references a key provided in the keys list.

For the policy with the keys, one can then derive pkScripts for
receive and change addresses and use these to create addresses.

messages/btc.proto

@@ -52,9 +52,17 @@ message BTCScriptConfig {
     ScriptType script_type = 4;
   }
 
+  // A policy as specified by 'Wallet policies':
+  // https://github.com/bitcoin/bips/pull/1389
+  message Policy {
+    string policy = 1;
+    repeated KeyOriginInfo keys = 2;
+  }
+
   oneof config {
     SimpleType simple_type = 1;
     Multisig multisig = 2;
+    Policy policy = 3;
   }
 }
 

messages/common.proto

@@ -40,3 +40,9 @@ message XPub {
 message Keypath {
   repeated uint32 keypath = 1;
 }
+
+message KeyOriginInfo {
+  bytes root_fingerprint = 1;
+  repeated uint32 keypath = 2;
+  XPub xpub = 3;
+}

py/bitbox02/bitbox02/communication/generated/btc_pb2.pyi

@@ -123,19 +123,40 @@ class BTCScriptConfig(google.protobuf.message.Message):
             ) -> None: ...
         def ClearField(self, field_name: typing_extensions.Literal["our_xpub_index",b"our_xpub_index","script_type",b"script_type","threshold",b"threshold","xpubs",b"xpubs"]) -> None: ...
 
+    class Policy(google.protobuf.message.Message):
+        """A policy as specified by 'Wallet policies':
+        https://github.com/bitcoin/bips/pull/1389
+        """
+        DESCRIPTOR: google.protobuf.descriptor.Descriptor
+        POLICY_FIELD_NUMBER: builtins.int
+        KEYS_FIELD_NUMBER: builtins.int
+        policy: typing.Text
+        @property
+        def keys(self) -> google.protobuf.internal.containers.RepeatedCompositeFieldContainer[common_pb2.KeyOriginInfo]: ...
+        def __init__(self,
+            *,
+            policy: typing.Text = ...,
+            keys: typing.Optional[typing.Iterable[common_pb2.KeyOriginInfo]] = ...,
+            ) -> None: ...
+        def ClearField(self, field_name: typing_extensions.Literal["keys",b"keys","policy",b"policy"]) -> None: ...
+
     SIMPLE_TYPE_FIELD_NUMBER: builtins.int
     MULTISIG_FIELD_NUMBER: builtins.int
+    POLICY_FIELD_NUMBER: builtins.int
     simple_type: global___BTCScriptConfig.SimpleType.ValueType
     @property
     def multisig(self) -> global___BTCScriptConfig.Multisig: ...
+    @property
+    def policy(self) -> global___BTCScriptConfig.Policy: ...
     def __init__(self,
         *,
         simple_type: global___BTCScriptConfig.SimpleType.ValueType = ...,
         multisig: typing.Optional[global___BTCScriptConfig.Multisig] = ...,
+        policy: typing.Optional[global___BTCScriptConfig.Policy] = ...,
         ) -> None: ...
-    def HasField(self, field_name: typing_extensions.Literal["config",b"config","multisig",b"multisig","simple_type",b"simple_type"]) -> builtins.bool: ...
-    def ClearField(self, field_name: typing_extensions.Literal["config",b"config","multisig",b"multisig","simple_type",b"simple_type"]) -> None: ...
-    def WhichOneof(self, oneof_group: typing_extensions.Literal["config",b"config"]) -> typing.Optional[typing_extensions.Literal["simple_type","multisig"]]: ...
+    def HasField(self, field_name: typing_extensions.Literal["config",b"config","multisig",b"multisig","policy",b"policy","simple_type",b"simple_type"]) -> builtins.bool: ...
+    def ClearField(self, field_name: typing_extensions.Literal["config",b"config","multisig",b"multisig","policy",b"policy","simple_type",b"simple_type"]) -> None: ...
+    def WhichOneof(self, oneof_group: typing_extensions.Literal["config",b"config"]) -> typing.Optional[typing_extensions.Literal["simple_type","multisig","policy"]]: ...
 global___BTCScriptConfig = BTCScriptConfig
 
 class BTCPubRequest(google.protobuf.message.Message):

py/bitbox02/bitbox02/communication/generated/common_pb2.pyi

@@ -77,3 +77,23 @@ class Keypath(google.protobuf.message.Message):
         ) -> None: ...
     def ClearField(self, field_name: typing_extensions.Literal["keypath",b"keypath"]) -> None: ...
 global___Keypath = Keypath
+
+class KeyOriginInfo(google.protobuf.message.Message):
+    DESCRIPTOR: google.protobuf.descriptor.Descriptor
+    ROOT_FINGERPRINT_FIELD_NUMBER: builtins.int
+    KEYPATH_FIELD_NUMBER: builtins.int
+    XPUB_FIELD_NUMBER: builtins.int
+    root_fingerprint: builtins.bytes
+    @property
+    def keypath(self) -> google.protobuf.internal.containers.RepeatedScalarFieldContainer[builtins.int]: ...
+    @property
+    def xpub(self) -> global___XPub: ...
+    def __init__(self,
+        *,
+        root_fingerprint: builtins.bytes = ...,
+        keypath: typing.Optional[typing.Iterable[builtins.int]] = ...,
+        xpub: typing.Optional[global___XPub] = ...,
+        ) -> None: ...
+    def HasField(self, field_name: typing_extensions.Literal["xpub",b"xpub"]) -> builtins.bool: ...
+    def ClearField(self, field_name: typing_extensions.Literal["keypath",b"keypath","root_fingerprint",b"root_fingerprint","xpub",b"xpub"]) -> None: ...
+global___KeyOriginInfo = KeyOriginInfo

src/rust/bitbox02-rust/src/shiftcrypto.bitbox02.rs

@@ -38,6 +38,16 @@ pub struct Keypath {
 }
 #[allow(clippy::derive_partial_eq_without_eq)]
 #[derive(Clone, PartialEq, ::prost::Message)]
+pub struct KeyOriginInfo {
+    #[prost(bytes = "vec", tag = "1")]
+    pub root_fingerprint: ::prost::alloc::vec::Vec<u8>,
+    #[prost(uint32, repeated, tag = "2")]
+    pub keypath: ::prost::alloc::vec::Vec<u32>,
+    #[prost(message, optional, tag = "3")]
+    pub xpub: ::core::option::Option<XPub>,
+}
+#[allow(clippy::derive_partial_eq_without_eq)]
+#[derive(Clone, PartialEq, ::prost::Message)]
 pub struct CheckBackupRequest {
     #[prost(bool, tag = "1")]
     pub silent: bool,
@@ -203,7 +213,7 @@ pub struct AntiKleptoSignatureRequest {
 #[allow(clippy::derive_partial_eq_without_eq)]
 #[derive(Clone, PartialEq, ::prost::Message)]
 pub struct BtcScriptConfig {
-    #[prost(oneof = "btc_script_config::Config", tags = "1, 2")]
+    #[prost(oneof = "btc_script_config::Config", tags = "1, 2, 3")]
     pub config: ::core::option::Option<btc_script_config::Config>,
 }
 /// Nested message and enum types in `BTCScriptConfig`.
@@ -265,6 +275,16 @@ pub mod btc_script_config {
             }
         }
     }
+    /// A policy as specified by 'Wallet policies':
+    /// <https://github.com/bitcoin/bips/pull/1389>
+    #[allow(clippy::derive_partial_eq_without_eq)]
+    #[derive(Clone, PartialEq, ::prost::Message)]
+    pub struct Policy {
+        #[prost(string, tag = "1")]
+        pub policy: ::prost::alloc::string::String,
+        #[prost(message, repeated, tag = "2")]
+        pub keys: ::prost::alloc::vec::Vec<super::KeyOriginInfo>,
+    }
     /// SimpleType is a "simple" script: one public key, no additional inputs.
     #[derive(
         Clone,
@@ -312,6 +332,8 @@ pub mod btc_script_config {
         SimpleType(i32),
         #[prost(message, tag = "2")]
         Multisig(Multisig),
+        #[prost(message, tag = "3")]
+        Policy(Policy),
     }
 }
 #[allow(clippy::derive_partial_eq_without_eq)]