513 lines
17 KiB
Python
513 lines
17 KiB
Python
# (c) Copyright 2025 by Coinkite Inc. This file is covered by license found in COPYING-CC.
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#
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# Signatures over text ... not transactions.
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#
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import stash, chains, sys, gc, ngu, ujson, version
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from ubinascii import b2a_base64, a2b_base64
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from ubinascii import hexlify as b2a_hex
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from ubinascii import unhexlify as a2b_hex
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from uhashlib import sha256
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from public_constants import MSG_SIGNING_MAX_LENGTH
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from public_constants import AF_CLASSIC, AF_P2WPKH, AF_P2WPKH_P2SH
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from charcodes import KEY_QR, KEY_NFC, KEY_CANCEL
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from ux import (ux_show_story, OK, ux_enter_bip32_index, ux_input_text, the_ux,
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import_export_prompt, ux_aborted)
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from utils import problem_file_line, to_ascii_printable, show_single_address, node_from_privkey
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from files import CardSlot, CardMissingError, needs_microsd
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def rfc_signature_template(msg, addr, sig):
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# RFC2440 <https://www.ietf.org/rfc/rfc2440.txt> style signatures, popular
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# since the genesis block, but not really part of any BIP as far as I know.
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#
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return [
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"-----BEGIN BITCOIN SIGNED MESSAGE-----\n",
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"%s\n" % msg,
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"-----BEGIN BITCOIN SIGNATURE-----\n",
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"%s\n" % addr,
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"%s\n" % sig,
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"-----END BITCOIN SIGNATURE-----\n"
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]
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def parse_armored_signature_file(contents):
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# XXX limited parser: will fail w/ messages containing dashes
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sep = "-----"
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assert contents.count(sep) == 6, "Armor text MUST be surrounded by exactly five (5) dashes."
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temp = contents.split(sep)
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msg = temp[2].strip()
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addr_sig = temp[4].strip()
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addr, sig_str = addr_sig.split()
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return msg, addr, sig_str
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def verify_signature(msg, addr, sig_str):
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# Look at a base64 signature, and given address. Do full verification.
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# - raise on errors
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# - return warnings as string: can only be mismatch between addr format encoded in recid
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warnings = ""
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script = None
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hash160 = None
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invalid_addr_fmt_msg = "Invalid address format - must be one of p2pkh, p2sh-p2wpkh, or p2wpkh."
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invalid_addr = "Invalid signature for message."
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if addr[0] in "1mn":
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addr_fmt = AF_CLASSIC
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decoded_addr = ngu.codecs.b58_decode(addr)
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hash160 = decoded_addr[1:] # remove prefix
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elif addr.startswith("bc1q") or addr.startswith("tb1q") or addr.startswith("bcrt1q"):
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if len(addr) > 44: # testnet/mainnet max singlesig len 42, regtest 44
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# p2wsh
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raise ValueError(invalid_addr_fmt_msg)
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addr_fmt = AF_P2WPKH
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_, _, hash160 = ngu.codecs.segwit_decode(addr)
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elif addr[0] in "32":
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addr_fmt = AF_P2WPKH_P2SH
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decoded_addr = ngu.codecs.b58_decode(addr)
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script = decoded_addr[1:] # remove prefix
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else:
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raise ValueError(invalid_addr_fmt_msg)
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try:
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sig_bytes = a2b_base64(sig_str)
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if not sig_bytes or len(sig_bytes) != 65:
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# can return b'' in case of wrong, can also raise
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raise ValueError("invalid encoding")
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header_byte = sig_bytes[0]
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header_base = chains.current_chain().sig_hdr_base(addr_fmt)
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if (header_byte - header_base) not in (0, 1, 2, 3):
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# wrong header value only - this can still verify OK
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warnings += "Specified address format does not match signature header byte format."
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# least two significant bits
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rec_id = (header_byte - 27) & 0x03
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# need to normalize it to 31 base for ngu
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new_header_byte = 31 + rec_id
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sig = ngu.secp256k1.signature(bytes([new_header_byte]) + sig_bytes[1:])
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except ValueError as e:
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raise ValueError("Parsing signature failed - %s." % str(e))
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digest = chains.current_chain().hash_message(msg.encode('ascii'))
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try:
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rec_pubkey = sig.verify_recover(digest)
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except ValueError as e:
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raise ValueError("Invalid signature for msg - %s." % str(e))
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rec_pubkey_bytes = rec_pubkey.to_bytes()
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rec_hash160 = ngu.hash.hash160(rec_pubkey_bytes)
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if script:
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target = bytes([0, 20]) + rec_hash160
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target = ngu.hash.hash160(target)
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if target != script:
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raise ValueError(invalid_addr)
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else:
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if rec_hash160 != hash160:
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raise ValueError(invalid_addr)
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return warnings
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async def verify_armored_signed_msg(contents, digest_check=True):
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# Verify on-disk checksums of files listed inside a signed file.
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# - digest_check=False for NFC cases, where we do not have filesystem
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from glob import dis
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dis.fullscreen("Verifying...")
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try:
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msg, addr, sig_str = parse_armored_signature_file(contents)
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except Exception as e:
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e_line = problem_file_line(e)
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await ux_show_story("Malformed signature file. %s %s" % (str(e), e_line), title="FAILURE")
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return
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try:
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sig_warn = verify_signature(msg, addr, sig_str)
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except Exception as e:
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await ux_show_story(str(e), title="ERROR")
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return
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title = "CORRECT"
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warn_msg = ""
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err_msg = ""
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story = "Good signature by address:\n%s" % show_single_address(addr)
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if digest_check:
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digest_prob = verify_signed_file_digest(msg)
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if digest_prob:
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err, digest_warn = digest_prob
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if digest_warn:
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title = "WARNING"
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wmsg_base = "not present. Contents verification not possible."
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if len(digest_warn) == 1:
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fname = digest_warn[0][0]
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warn_msg += "'%s' is %s" % (fname, wmsg_base)
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else:
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warn_msg += "Files:\n" + "\n".join("> %s" % fname for fname, _ in digest_warn)
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warn_msg += "\nare %s" % wmsg_base
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if err:
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title = "ERROR"
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for fname, calc, got in err:
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err_msg += ("Referenced file '%s' has wrong contents.\n"
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"Got:\n%s\n\nExpected:\n%s" % (fname, got, calc))
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if sig_warn:
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# we know not ours only because wrong recid header used & not BIP-137 compliant
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story = "Correctly signed, but not by this Coldcard. %s" % sig_warn
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await ux_show_story('\n\n'.join(m for m in [err_msg, story, warn_msg] if m), title=title)
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async def verify_txt_sig_file(filename):
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# copy message into memory
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try:
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with CardSlot() as card:
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with card.open(filename, 'rt') as fd:
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text = fd.read()
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except CardMissingError:
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await needs_microsd()
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return
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except Exception as e:
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await ux_show_story('Error: ' + str(e))
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return
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await verify_armored_signed_msg(text)
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async def msg_sign_ux_get_subpath(addr_fmt):
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# Ask for account number, and maybe change component of path for signature.
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# - return full derivation path to be used.
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purpose = chains.af_to_bip44_purpose(addr_fmt)
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chain_n = chains.current_chain().b44_cointype
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acct = await ux_enter_bip32_index('Account Number:') or 0
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ch = await ux_show_story(title="Change?",
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msg="Press (0) to use internal/change address,"
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" %s to use external/receive address." % OK, escape="0")
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change = 1 if ch == '0' else 0
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idx = await ux_enter_bip32_index('Index Number:') or 0
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return "m/%dh/%dh/%dh/%d/%d" % (purpose, chain_n, acct, change, idx)
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def sign_export_contents(content_list, deriv, addr_fmt, pk=None):
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# Return signed message over hashes of files.
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msg2sign = make_signature_file_msg(content_list)
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bitcoin_digest = chains.current_chain().hash_message(msg2sign)
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sig_bytes, addr = sign_message_digest(bitcoin_digest, deriv, "Signing...", addr_fmt, pk=pk)
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sig = b2a_base64(sig_bytes).decode().strip()
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return rfc_signature_template(addr=addr, msg=msg2sign.decode(), sig=sig)
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def verify_signed_file_digest(msg):
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# Look inside a list of hashs and file names, and
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# verify at their actual hashes and return list of issues if any.
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parsed_msg = parse_signature_file_msg(msg)
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if not parsed_msg:
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# not our format
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return
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try:
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err, warn = [], []
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with CardSlot() as card:
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for digest, fname in parsed_msg:
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path = card.abs_path(fname)
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if not card.exists(path):
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warn.append((fname, None))
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continue
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path = card.abs_path(fname)
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md = sha256()
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with open(path, "rb") as f:
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while True:
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chunk = f.read(1024)
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if not chunk:
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break
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md.update(chunk)
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h = b2a_hex(md.digest()).decode().strip()
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if h != digest:
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err.append((fname, h, digest))
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except:
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# fail silently if issues with reading files or SD issues
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# no digest checking
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return
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return err, warn
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def write_sig_file(content_list, derive=None, addr_fmt=AF_CLASSIC, pk=None, sig_name=None):
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if derive is None:
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ct = chains.current_chain().b44_cointype
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derive = "m/44'/%d'/0'/0/0" % ct
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fpath = content_list[0][1]
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if len(content_list) > 1:
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# we're signing contents of more files - need generic name for sig file
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assert sig_name
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sig_nice = sig_name + ".sig"
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sig_fpath = fpath.rsplit("/", 1)[0] + "/" + sig_nice
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else:
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sig_fpath = fpath.rsplit(".", 1)[0] + ".sig"
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sig_nice = sig_fpath.split("/")[-1]
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sig_gen = sign_export_contents([(h, f.split("/")[-1]) for h, f in content_list],
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derive, addr_fmt, pk=pk)
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with open(sig_fpath, 'wt') as fd:
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for i, part in enumerate(sig_gen):
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fd.write(part)
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return sig_nice
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def validate_text_for_signing(text, only_printable=True):
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# Check for some UX/UI traps in the message itself.
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# - messages must be short and ascii only. Our charset is limited
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# - too many spaces, leading/trailing can be an issue
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# MSG_MAX_SPACES = 4 # impt. compared to -=- positioning
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result = to_ascii_printable(text, only_printable=only_printable)
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length = len(result)
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assert length >= 2, "msg too short (min. 2)"
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assert length <= MSG_SIGNING_MAX_LENGTH, "msg too long (max. %d)" % MSG_SIGNING_MAX_LENGTH
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assert " " not in result, 'too many spaces together in msg(max. 3)'
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# other confusion w/ whitepace
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assert result[0] != ' ', 'leading space(s) in msg'
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assert result[-1] != ' ', 'trailing space(s) in msg'
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# looks ok
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return result
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def addr_fmt_from_subpath(subpath):
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if not subpath:
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af = "p2pkh"
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elif subpath[:4] == "m/84":
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af = "p2wpkh"
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elif subpath[:4] == "m/49":
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af = "p2sh-p2wpkh"
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else:
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af = "p2pkh"
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return af
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def parse_msg_sign_request(data):
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subpath = ""
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addr_fmt = None
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is_json = False
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# sparrow compat
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if "signmessage" in data:
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try:
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mark, subpath, *msg_line = data.split(" ", 2)
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assert mark == "signmessage"
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# subpath will be verified & cleaned later
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assert msg_line[0][:6] == "ascii:"
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text = msg_line[0][6:]
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return text, subpath, addr_fmt_from_subpath(subpath), is_json
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except:pass
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# ===
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try:
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data_dict = ujson.loads(data.strip())
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text = data_dict.get("msg", None)
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if text is None:
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raise AssertionError("MSG required")
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subpath = data_dict.get("subpath", subpath)
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addr_fmt = data_dict.get("addr_fmt", addr_fmt)
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is_json = True
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except ValueError:
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lines = data.split("\n")
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assert lines, "min 1 line"
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assert len(lines) <= 3, "max 3 lines"
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if len(lines) == 1:
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text = lines[0]
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elif len(lines) == 2:
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text, subpath = lines
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else:
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text, subpath, addr_fmt = lines
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if not addr_fmt:
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addr_fmt = addr_fmt_from_subpath(subpath)
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if not subpath:
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subpath = chains.STD_DERIVATIONS[addr_fmt]
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subpath = subpath.format(
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coin_type=chains.current_chain().b44_cointype,
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account=0, change=0, idx=0
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)
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return text, subpath, addr_fmt, is_json
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def make_signature_file_msg(content_list):
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# list of tuples consisting of (hash, file_name)
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return b"\n".join([
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b2a_hex(h) + b" " + fname.encode()
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for h, fname in content_list
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])
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def parse_signature_file_msg(msg):
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# only succeed for our format digest + 2 spaces + fname
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try:
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res = []
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lines = msg.split('\n')
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for ln in lines:
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d, fn = ln.split(' ')
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# should not need to strip if our file format, so dont
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# is hex? is 32 bytes long?
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assert len(a2b_hex(d)) == 32
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res.append((d, fn))
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return res
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except:
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return
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def sign_message_digest(digest, subpath, prompt, addr_fmt=AF_CLASSIC, pk=None):
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# do the signature itself!
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from glob import dis
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ch = chains.current_chain()
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if prompt:
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dis.fullscreen(prompt, percent=.25)
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if pk is None:
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with stash.SensitiveValues() as sv:
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node = sv.derive_path(subpath)
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dis.progress_sofar(50, 100)
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pk = node.privkey()
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addr = ch.address(node, addr_fmt)
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else:
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# if private key is provided, derivation subpath is ignored
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# and given private key is used for signing.
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node = node_from_privkey(pk)
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dis.progress_sofar(50, 100)
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addr = ch.address(node, addr_fmt)
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dis.progress_sofar(75, 100)
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rv = ngu.secp256k1.sign(pk, digest, 0).to_bytes()
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# AF_CLASSIC header byte base 31 is returned by default from ngu - NOOP
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if addr_fmt != AF_CLASSIC:
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# ngu only produces header base for compressed p2pkh, anyways get only rec_id
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rv = bytearray(rv)
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rec_id = (rv[0] - 27) & 0x03
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rv[0] = rec_id + ch.sig_hdr_base(addr_fmt=addr_fmt)
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dis.progress_bar_show(1)
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return rv, addr
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async def ux_sign_msg(txt, approved_cb=None, kill_menu=True):
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from menu import MenuSystem, MenuItem
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async def done(_1, _2, item):
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from auth import approve_msg_sign
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text, af = item.arg
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subpath = await msg_sign_ux_get_subpath(af)
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await approve_msg_sign(text, subpath, af, approved_cb=approved_cb,
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kill_menu=kill_menu, only_printable=False)
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# pick address format
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rv = [
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MenuItem(chains.addr_fmt_label(af), f=done, arg=(txt, af))
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for af in chains.SINGLESIG_AF
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]
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the_ux.push(MenuSystem(rv))
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async def msg_signing_done(signature, address, text):
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ch = await import_export_prompt("Signed Msg")
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if ch == KEY_CANCEL:
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return
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if isinstance(ch, dict):
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await sd_sign_msg_done(signature, address, text, "msg_sign", **ch)
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elif version.has_qr and ch == KEY_QR:
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from ux_q1 import qr_msg_sign_done
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await qr_msg_sign_done(signature, address, text)
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elif ch in KEY_NFC+"3":
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from glob import NFC
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if NFC:
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await NFC.msg_sign_done(signature, address, text)
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async def sign_with_own_address(subpath, addr_fmt):
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# used for cases where we already have the key picked, but need the message:
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# * address_explorer custom path
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# * positive ownership test
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to_sign = await ux_input_text("", scan_ok=True, prompt="Enter MSG") # max len is 100 only here
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if not to_sign: return
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from auth import approve_msg_sign
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await approve_msg_sign(to_sign, subpath, addr_fmt, approved_cb=msg_signing_done, kill_menu=True)
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async def sd_sign_msg_done(signature, address, text, base=None, orig_path=None,
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slot_b=None, force_vdisk=False):
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from glob import dis
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dis.fullscreen('Generating...')
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out_fn = None
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sig = b2a_base64(signature).decode('ascii').strip()
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while 1:
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# try to put back into same spot
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# add -signed to end.
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target_fname = base + '-signed.txt'
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lst = [orig_path]
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if orig_path:
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lst.append(None)
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for path in lst:
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try:
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with CardSlot(readonly=True, slot_b=slot_b, force_vdisk=force_vdisk) as card:
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out_full, out_fn = card.pick_filename(target_fname, path)
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out_path = path
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if out_full: break
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except CardMissingError:
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prob = 'Missing card.\n\n'
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out_fn = None
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if not out_fn:
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# need them to insert a card
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prob = ''
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else:
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# attempt write-out
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try:
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dis.fullscreen("Saving...")
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with CardSlot(slot_b=slot_b, force_vdisk=force_vdisk) as card:
|
|
with card.open(out_full, 'wt') as fd:
|
|
# save in full RFC style
|
|
# gen length is 6
|
|
gen = rfc_signature_template(addr=address, msg=text, sig=sig)
|
|
for i, part in enumerate(gen):
|
|
fd.write(part)
|
|
|
|
# success and done!
|
|
break
|
|
|
|
except OSError as exc:
|
|
prob = 'Failed to write!\n\n%s\n\n' % exc
|
|
# sys.print_exception(exc)
|
|
# fall through to try again
|
|
|
|
# prompt them to input another card?
|
|
ch = await ux_show_story(prob + "Please insert an SDCard to receive signed message, "
|
|
"and press %s." % OK, title="Need Card")
|
|
if ch == 'x':
|
|
await ux_aborted()
|
|
return
|
|
|
|
# done.
|
|
msg = "Created new file:\n\n%s" % out_fn
|
|
await ux_show_story(msg, title='File Signed')
|
|
|
|
|
|
|
|
# EOF
|