feat: sp address support

Author: notTanveer

src/seedsigner/gui/components.py

@@ -936,6 +936,7 @@ class FormattedAddress(BaseComponent):
     screen_y: int = 0
     address: str = None
     max_lines: int = None
+    line_spacing: int = GUIConstants.BODY_LINE_SPACING
     font_name: str = GUIConstants.FIXED_WIDTH_FONT_NAME
     font_size: int = 24
     font_accent_color: str = GUIConstants.ACCENT_COLOR
@@ -1074,7 +1075,7 @@ def __post_init__(self):
                     ))
 
                 remaining_display_str = remaining_display_str[max_chars_per_line:]
-                cur_y += char_height + GUIConstants.BODY_LINE_SPACING
+                cur_y += char_height + self.line_spacing
 
         self.height = cur_y
 

src/seedsigner/gui/screens/seed_screens.py

@@ -571,6 +571,155 @@ def __post_init__(self):
 
 
 
+@dataclass
+class SeedBIP352GeneratePaymentAddressScreen(ButtonListScreen):
+    payment_address: str = None
+
+    def __post_init__(self):
+        self.title = "Payment Address"
+        self.is_bottom_list = True
+        super().__post_init__()
+
+        self.components.append(FormattedAddress(
+            address=self.payment_address,
+            font_size=GUIConstants.get_body_font_size() + 4,
+            line_spacing=GUIConstants.BODY_LINE_SPACING - 2,
+            screen_y=self.top_nav.height
+        ))
+
+        
+
+@dataclass
+class SeedBIP352ExportScanningPrivkeyDetailsScreen(WarningEdgesMixin, ButtonListScreen):
+    is_bottom_list: bool = True
+    fingerprint: str = None
+    has_passphrase: bool = False
+    derivation_path: str = "m/352'/0'/0'/1'/0"
+    scanning_privkey: str = "xprv..."
+    status_color: str = GUIConstants.DIRE_WARNING_COLOR
+
+    def __post_init__(self):
+        self.button_data = [ButtonOption(_("Export Privkey via QR"))]
+        self.title = _("Scan Private Key Details")
+
+        super().__post_init__()
+
+        self.fingerprint_line = IconTextLine(
+            icon_name=SeedSignerIconConstants.FINGERPRINT,
+            icon_color=GUIConstants.INFO_COLOR,
+            label_text=_("Fingerprint"),
+            value_text=self.fingerprint,
+            screen_x=GUIConstants.COMPONENT_PADDING,
+            screen_y=self.top_nav.height + GUIConstants.COMPONENT_PADDING,
+        )
+        self.components.append(self.fingerprint_line)
+
+        self.derivation_line = IconTextLine(
+            icon_name=SeedSignerIconConstants.DERIVATION,
+            icon_color=GUIConstants.INFO_COLOR,
+            label_text=_("Derivation"),
+            value_text=self.derivation_path,
+            screen_x=GUIConstants.COMPONENT_PADDING,
+            screen_y=self.components[-1].screen_y + self.components[-1].height + int(1.5*GUIConstants.COMPONENT_PADDING),
+        )
+        self.components.append(self.derivation_line)
+
+        font_name = GUIConstants.FIXED_WIDTH_FONT_NAME
+        font_size = GUIConstants.get_body_font_size() + 2
+        left, top, right, bottom  = Fonts.get_font(font_name, font_size).getbbox("X")
+        char_width = right - left
+        num_chars = int((self.canvas_width - 2*GUIConstants.COMPONENT_PADDING) / char_width) - 3
+
+        self.privkey_line = IconTextLine(
+            icon_name=FontAwesomeIconConstants.X,
+            icon_color=GUIConstants.INFO_COLOR,
+            label_text=_("Scan Private Key"),
+            value_text=f"{self.scanning_privkey[:num_chars]}...",
+            font_name=GUIConstants.FIXED_WIDTH_FONT_NAME,
+            font_size=GUIConstants.get_body_font_size() + 2,
+            screen_x=GUIConstants.COMPONENT_PADDING,
+            screen_y=self.components[-1].screen_y + self.components[-1].height + int(1.5*GUIConstants.COMPONENT_PADDING),
+        )
+        self.components.append(self.privkey_line)
+
+
+
+@dataclass
+class SeedBIP352ExportSigningPubkeyDetailsScreen(WarningEdgesMixin, ButtonListScreen):
+    # Customize defaults
+    is_bottom_list: bool = True
+    fingerprint: str = None
+    has_passphrase: bool = False
+    derivation_path: str = "m/352'/0'/0'/0'/0"
+    signing_pubkey: str = "xpub..."
+
+    def __post_init__(self):
+        self.button_data = [ButtonOption(_("Export Pubkey via QR"))]
+        self.title = _("Spend Pubkey Details")
+
+        super().__post_init__()
+
+        # Set up the fingerprint and passphrase displays
+        self.fingerprint_line = IconTextLine(
+            icon_name=SeedSignerIconConstants.FINGERPRINT,
+            icon_color=GUIConstants.INFO_COLOR,
+            label_text=_("Fingerprint"),
+            value_text=self.fingerprint,
+            screen_x=GUIConstants.COMPONENT_PADDING,
+            screen_y=self.top_nav.height + GUIConstants.COMPONENT_PADDING,
+        )
+        self.components.append(self.fingerprint_line)
+
+        self.derivation_line = IconTextLine(
+            icon_name=SeedSignerIconConstants.DERIVATION,
+            icon_color=GUIConstants.INFO_COLOR,
+            label_text=_("Derivation"),
+            value_text=self.derivation_path,
+            screen_x=GUIConstants.COMPONENT_PADDING,
+            screen_y=self.components[-1].screen_y + self.components[-1].height + int(1.5*GUIConstants.COMPONENT_PADDING),
+        )
+        self.components.append(self.derivation_line)
+
+        font_name = GUIConstants.FIXED_WIDTH_FONT_NAME
+        font_size = GUIConstants.get_body_font_size() + 2
+        left, top, right, bottom  = Fonts.get_font(font_name, font_size).getbbox("X")
+        char_width = right - left
+        num_chars = int((self.canvas_width - 2*GUIConstants.COMPONENT_PADDING) / char_width) - 3
+
+        self.pubkey_line = IconTextLine(
+            icon_name=FontAwesomeIconConstants.X,
+            icon_color=GUIConstants.INFO_COLOR,
+            label_text=_("Spend Public Key"),
+            value_text=f"{self.signing_pubkey[:num_chars]}...",
+            font_name=GUIConstants.FIXED_WIDTH_FONT_NAME,
+            font_size=GUIConstants.get_body_font_size() + 2,
+            screen_x=GUIConstants.COMPONENT_PADDING,
+            screen_y=self.components[-1].screen_y + self.components[-1].height + int(1.5*GUIConstants.COMPONENT_PADDING),
+        )
+        self.components.append(self.pubkey_line)
+
+
+
+@dataclass
+class SeedBIP352LabelEntryScreen(KeyboardScreen):
+    """
+    Currently, labels are restricted to numeric characters only as a basic safeguard.
+    TODO: Extend support to any arbitrary char string in future updates.
+    """
+    def __post_init__(self):
+        self.title = _("Enter Label")
+        self.user_input = ""
+
+        # Specify the keys in the keyboard - numeric only
+        self.rows = 3
+        self.cols = 5
+        self.keys_charset = "0123456789"
+        self.show_save_button = True
+
+        super().__post_init__()
+
+
+
 @dataclass
 class SeedWordsBackupTestPromptScreen(ButtonListScreen):
     def __post_init__(self):

src/seedsigner/helpers/embit_utils.py

@@ -3,11 +3,12 @@
 from binascii import b2a_base64
 from hashlib import sha256
 
-from embit import bip32, compact, ec
+from embit import bech32, bip32, compact, ec
 from embit.bip32 import HDKey
 from embit.descriptor import Descriptor
 from embit.networks import NETWORKS
 from embit.util import secp256k1
+from embit.hashes import tagged_hash
 
 
 from seedsigner.models.settings_definition import SettingsConstants
@@ -200,3 +201,40 @@ def sign_message(seed_bytes: bytes, derivation: str, msg: bytes, compressed: boo
     flag = bytes([27 + flag + c])
     ser = flag + secp256k1.ecdsa_signature_serialize_compact(sig._sig)
     return b2a_base64(ser).strip().decode()
+
+
+
+# Basic BIP-352 Silent Payments support
+def encode_silent_payment_address(B_scan: ec.PublicKey, B_m: ec.PublicKey, network: str = "main", version: int = 0) -> str:
+    """
+    Adapted from https://github.com/bitcoin/bips/blob/master/bip-0352/reference.py
+
+    Generates the recipient's reusable silent payment address for a given:
+        * scanning pubkey `B_scan`
+        * spending pubkey `B_m`
+    """
+    data = bech32.convertbits(B_scan.sec() + B_m.sec(), 8, 5)
+    hrp = "sp" if network == "main" else "tsp"
+    return bech32.bech32_encode(bech32.Encoding.BECH32M, hrp, [version] + data)
+
+
+
+def encode_labeled_silent_payment_address(b_scan: ec.PrivateKey, B_spend: ec.PublicKey, label, network: str = "main", version: int = 0) -> str:
+    """
+    The spending key is tweaked with the label to generate a labeled silent payment address.
+    see: https://github.com/bitcoin/bips/blob/master/bip-0352.mediawiki#address-encoding
+    `label` must be an int, str, or bytes.
+    """
+    if isinstance(label, int):
+        label_bytes = label.to_bytes(4, "big")
+    elif isinstance(label, str):
+        label_bytes = label.encode()
+    elif isinstance(label, bytes):
+        label_bytes = label
+    else:
+        raise Exception("Label must be an int, str, or bytes.")
+
+    tweak = tagged_hash("BIP0352/Label", b_scan.secret + label_bytes)
+    label_pubkey = ec.PublicKey(secp256k1.ec_pubkey_add(secp256k1.ec_pubkey_parse(B_spend.sec()), tweak))
+
+    return encode_silent_payment_address(b_scan.get_public_key(), label_pubkey, network=network, version=version)

src/seedsigner/models/seed.py

@@ -9,6 +9,7 @@
 from typing import List
 
 from seedsigner.models.settings import SettingsConstants
+from seedsigner.helpers import embit_utils
 
 logger = logging.getLogger(__name__)
 
@@ -164,6 +165,45 @@ def get_bip85_child_mnemonic(self, bip85_index: int, bip85_num_words: int, netwo
         return bip85.derive_mnemonic(root, bip85_num_words, bip85_index)
 
 
+    # ----------------- BIP-352 Silent Payments support -----------------
+    def _derive_bip352_key(self, is_scanning_key: bool = True, account: int = 0, network: str = SettingsConstants.MAINNET):
+        """
+            Derives the BIP-352 scanning or signing key.
+
+            see: https://github.com/bitcoin/bips/blob/master/bip-0352.mediawiki#key-derivation
+        """
+        purpose = 352  # per BIP-352 spec
+        coin_type = 0 if network == SettingsConstants.MAINNET else 1  # mainnet coins vs testnet coins
+        key_type = 1 if is_scanning_key else 0  # per BIP-352 spec; scanning key vs spending key
+        derivation_path = f"m/{purpose}'/{coin_type}'/{account}'/{key_type}'/0"
+        root = bip32.HDKey.from_seed(self.seed_bytes, version=NETWORKS[SettingsConstants.map_network_to_embit(network)]["xprv"])
+        return root.derive(derivation_path)
+
+
+    def derive_bip352_scanning_key(self, account: int = 0, network: str = SettingsConstants.MAINNET):
+        return self._derive_bip352_key(is_scanning_key=True, account=account, network=network)
+
+
+    def derive_bip352_signing_key(self, account: int = 0, network: str = SettingsConstants.MAINNET):
+        return self._derive_bip352_key(is_scanning_key=False, account=account, network=network)
+    
+
+    def generate_bip352_silent_payment_address(self, network: str = SettingsConstants.MAINNET):
+        scanning_pk = self.derive_bip352_scanning_key(network=network)
+        signing_pk = self.derive_bip352_signing_key(network=network)
+        scanning_pubkey = scanning_pk.get_public_key()
+        signing_pubkey = signing_pk.get_public_key()
+        return embit_utils.encode_silent_payment_address(scanning_pubkey, signing_pubkey, network=SettingsConstants.map_network_to_embit(network))
+
+
+    def generate_bip352_silent_payment_labeled_address(self, label: str, network: str = SettingsConstants.MAINNET):
+        scanning_pk = self.derive_bip352_scanning_key(network=network)
+        signing_pk = self.derive_bip352_signing_key(network=network)
+        signing_pubkey = signing_pk.get_public_key()
+        return embit_utils.encode_labeled_silent_payment_address(scanning_pk, signing_pubkey, label, network=SettingsConstants.map_network_to_embit(network))
+    # ----------------- BIP-352 Silent Payments support -----------------
+
+
     ### override operators    
     def __eq__(self, other):
         if isinstance(other, Seed):

src/seedsigner/models/settings_definition.py

@@ -334,6 +334,7 @@ def map_network_to_embit(cls, network) -> str:
     SETTING__COMPACT_SEEDQR = "compact_seedqr"
     SETTING__BIP85_CHILD_SEEDS = "bip85_child_seeds"
     SETTING__ELECTRUM_SEEDS = "electrum_seeds"
+    SETTING__BIP352_SILENT_PAYMENTS = "bip352_silent_payments"
     SETTING__MESSAGE_SIGNING = "message_signing"
     SETTING__PRIVACY_WARNINGS = "privacy_warnings"
     SETTING__DIRE_WARNINGS = "dire_warnings"
@@ -399,6 +400,17 @@ def map_network_to_embit(cls, network) -> str:
     custom_extension = _mft("Custom Extension")
     LABEL__CUSTOM_EXTENSION = custom_extension
 
+    # BIP-352 Silent Payments options
+    BIP352__DISABLED = "D"
+    BIP352__ENABLED = "E"
+    BIP352__ENABLED_WITH_LABELS = "L"
+    
+    BIP352_OPTIONS = [
+        (BIP352__DISABLED, _mft("Disabled")),
+        (BIP352__ENABLED, _mft("Enable SP")),
+        (BIP352__ENABLED_WITH_LABELS, _mft("Enable SP + labels")),
+    ]
+
 
 
 @dataclass
@@ -699,6 +711,15 @@ class SettingsDefinition:
                       visibility=SettingsConstants.VISIBILITY__ADVANCED,
                       default_value=SettingsConstants.OPTION__ENABLED),
 
+        SettingsEntry(category=SettingsConstants.CATEGORY__FEATURES,
+            attr_name=SettingsConstants.SETTING__BIP352_SILENT_PAYMENTS,
+            abbreviated_name="bip352",
+            display_name="BIP-352 silent payments",
+            type=SettingsConstants.TYPE__SELECT_1,
+            visibility=SettingsConstants.VISIBILITY__ADVANCED,
+            selection_options=SettingsConstants.BIP352_OPTIONS,
+            default_value=SettingsConstants.BIP352__DISABLED),
+
 
         # Hardware config
         SettingsEntry(category=SettingsConstants.CATEGORY__SYSTEM,
@@ -728,7 +749,8 @@ class SettingsDefinition:
         #               display_name="Debug",
         #               visibility=SettingsConstants.VISIBILITY__DEVELOPER,
         #               default_value=SettingsConstants.OPTION__DISABLED),
-        
+
+
         # "Hidden" settings with no UI interaction
         SettingsEntry(category=SettingsConstants.CATEGORY__SYSTEM,
                       attr_name=SettingsConstants.SETTING__QR_BRIGHTNESS,