From 86b1a62b3c11fbe8e7d891243a0e657b5575ede1 Mon Sep 17 00:00:00 2001
From: Peter Todd <pete@petertodd.org>
Date: Wed, 15 Mar 2023 15:16:53 +0000
Subject: [PATCH] Add ots stamp-digest subcommand

---
 otsclient/args.py | 26 ++++++++++++++++++++++++++
 otsclient/cmds.py | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/otsclient/args.py b/otsclient/args.py
index e84b07e..89f568a 100644
--- a/otsclient/args.py
+++ b/otsclient/args.py
@@ -181,6 +181,31 @@ def parse_ots_args(raw_args):
                               help="Consider the timestamp complete if at least M calendars reply prior to the timeout. "
                                    "Default: %(default)s")
 
+    # ----- stamp-digest -----
+    parser_stamp_digest = subparsers.add_parser('stamp-digest',
+                                                help='Timestamp a digest')
+
+    parser_stamp_digest.add_argument('-c', '--calendar', metavar='URL', dest='calendar_urls', action='append', type=str,
+                                     default=[],
+                                     help='Create timestamp with the aid of a remote calendar. May be specified multiple times.')
+
+    parser_stamp_digest.add_argument('-b', '--btc-wallet', dest='use_btc_wallet', action='store_true',
+                                     help='Create timestamp locally with the local Bitcoin wallet.')
+
+    parser_stamp_digest.add_argument('hex_digest', metavar='DIGEST',
+                                     help='32-byte hex-encoded SHA256 digest')
+
+    parser_stamp_digest.add_argument('timestamp_fd', metavar='TIMESTAMP', type=argparse.FileType('wb'),
+                                     help='Timestamp filename')
+
+    parser_stamp_digest.add_argument("--timeout", type=int, default=5,
+                                     help="Timeout before giving up on a calendar. "
+                                          "Default: %(default)d")
+
+    parser_stamp_digest.add_argument("-m", type=int, default="2",
+                                     help="Consider the timestamp complete if at least M calendars reply prior to the timeout. "
+                                          "Default: %(default)s")
+
     # ----- upgrade -----
     parser_upgrade = subparsers.add_parser('upgrade', aliases=['u'],
                                            help='Upgrade remote calendar timestamps to be locally verifiable')
@@ -236,6 +261,7 @@ def parse_ots_args(raw_args):
 
 
     parser_stamp.set_defaults(cmd_func=otsclient.cmds.stamp_command)
+    parser_stamp_digest.set_defaults(cmd_func=otsclient.cmds.stamp_digest_command)
     parser_upgrade.set_defaults(cmd_func=otsclient.cmds.upgrade_command)
     parser_verify.set_defaults(cmd_func=otsclient.cmds.verify_command)
     parser_info.set_defaults(cmd_func=otsclient.cmds.info_command)
diff --git a/otsclient/cmds.py b/otsclient/cmds.py
index d18c185..3ecab5c 100644
--- a/otsclient/cmds.py
+++ b/otsclient/cmds.py
@@ -208,6 +208,47 @@ def stamp_command(args):
             logging.error("Failed to create timestamp %r: %s" % (timestamp_file_path, exp))
             sys.exit(1)
 
+def stamp_digest_command(args):
+    try:
+        digest = binascii.unhexlify(args.hex_digest.encode('utf8'))
+    except binascii.Error as exp:
+        logging.error("Bad digest %r: %s" % (args.hex_digest, exp))
+        sys.exit(1)
+
+    if len(digest) != 32:
+        logging.error("Bad digest %r: got %s bytes; expected 32" % (args.hex_digest, len(digest)))
+        sys.exit(1)
+
+    timestamp_file = DetachedTimestampFile(OpSHA256(), Timestamp(digest))
+
+    # Add nonce
+    #
+    # Remember that the files - and their timestamps - might get separated
+    # later, so if we didn't use a nonce for every file, the timestamp
+    # would leak information on the digests of adjacent files.
+    nonce_appended_stamp = timestamp_file.timestamp.ops.add(OpAppend(os.urandom(16)))
+    merkle_tip = nonce_appended_stamp.ops.add(OpSHA256())
+
+    if not args.calendar_urls:
+        # Neither calendar nor wallet specified; add defaults
+        args.calendar_urls.append('https://a.pool.opentimestamps.org')
+        args.calendar_urls.append('https://b.pool.opentimestamps.org')
+        args.calendar_urls.append('https://a.pool.eternitywall.com')
+        args.calendar_urls.append('https://ots.btc.catallaxy.com')
+
+    create_timestamp(merkle_tip, args.calendar_urls, args)
+
+    if args.wait:
+        upgrade_timestamp(merkle_tip, args)
+        logging.info("Timestamp complete; saving")
+
+    try:
+        ctx = StreamSerializationContext(args.timestamp_fd)
+        timestamp_file.serialize(ctx)
+    except IOError as exp:
+        logging.error("Failed to create timestamp file: %s" % (exp))
+        sys.exit(1)
+
 def is_timestamp_complete(stamp, args):
     """Determine if timestamp is complete and can be verified"""
     for msg, attestation in stamp.all_attestations():