closes #91 adds freetsa timestamp authority

src/auto_archiver/enrichers/__init__.py

@@ -8,4 +8,5 @@ from .whisper_enricher import WhisperEnricher
 from .pdq_hash_enricher import PdqHashEnricher
 from .metadata_enricher import MetadataEnricher
 from .meta_enricher import MetaEnricher
-from .ssl_enricher import SSLEnricher
+from .ssl_enricher import SSLEnricher
+from .freetsa_enricher import FreeTSAEnricher

src/auto_archiver/enrichers/freetsa_enricher.py

@@ -0,0 +1,55 @@
+import subprocess, os
+from loguru import logger
+
+from . import Enricher
+from ..core import Metadata, ArchivingContext, Media
+
+
+class FreeTSAEnricher(Enricher):
+    """
+    Uses freeTSA a Time Stamp Authority (https://freetsa.org/index_en.php) to generate two files: a TimeStampRequest .tsq and a TimeStampResponse .tsr . These, in combination with the public certificates available from the TSA, can be used to prove that a certain file existed at a certain time. This is useful for legal purposes, for example, to prove that a certain file was not tampered with after a certain date.
+
+    The information that gets timestamped is a text file with a list of the file hashes existing in the current archive, will depend on which archivers and enrichers ran before this one. Inner media files (like thumbnails) are not included in the .txt file. It should run AFTER the hash_enricher.  
+    """
+    name = "freetsa_enricher"
+
+    def __init__(self, config: dict) -> None:
+        super().__init__(config)
+
+    @staticmethod
+    def configs() -> dict:
+        return {}
+
+    def enrich(self, to_enrich: Metadata) -> None:
+        url = to_enrich.get_url()
+        logger.debug(f"Timestamping existing files for {url=}")
+
+        # create a new text file with the existing media hashes
+        hashes = [m.get("hash").replace("SHA-256:", "").replace("SHA3-512:", "") for m in to_enrich.media if m.get("hash")]
+
+        if not len(hashes):
+            logger.warning(f"No hashes found in {url=}")
+            return
+        
+        tmp_dir = ArchivingContext.get_tmp_dir()
+        hashes_fn = os.path.join(tmp_dir, "hashes.txt")
+
+        with open(hashes_fn, "w") as f: f.write("\n".join(hashes))
+
+        # create a TimeStampRequest .tsq
+        tsq_fn = os.path.join(tmp_dir, "file.tsq")
+        subprocess.run(["openssl", "ts", "-query", "-data", hashes_fn, "-no_nonce", "-sha512", "-out", tsq_fn])
+
+        # send the .tsq to the TSA and get a .tsr
+        tsr_fn = os.path.join(tmp_dir, "file.tsr")
+        subprocess.run(["curl", "-H", "Content-Type: application/timestamp-query", "--data-binary", f"@{tsq_fn}", "https://freetsa.org/tsr", "-o", tsr_fn], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+
+        assert os.path.exists(tsr_fn), f"Could not find {tsr_fn=} likely an error with the timestamping operation"
+
+        hashes_media = Media(filename=hashes_fn).set("verify", "visit https://freetsa.org/")
+        hashes_media.set("timestamp_authority_files", [
+            Media(filename=tsq_fn),
+            Media(filename=tsr_fn)
+        ])
+
+        to_enrich.add_media(hashes_media, id="timestamped_hashes")