Add tools/fetchacert.py, fetching exactly one chain from a log.

Also move a piece of common code from fetchallcerts.py to certtools.py.

1 files changed, 10 insertions, 0 deletions

diff --git a/tools/certtools.py b/tools/certtools.py
index 0e639f2..ffd631c 100644
--- a/tools/certtools.py
+++ b/tools/certtools.py
@@ -588,3 +588,13 @@ def verify_inclusion_proof(inclusion_proof, index, treesize, leafhash):
     chain = zip([(index, 0)] + nodes_for_index(index, treesize), [leafhash] + inclusion_proof)
     (_, hash) = reduce(lambda e1, e2: combine_two_hashes(e1, e2, treesize), chain)
     return hash
+
+def extract_original_entry(entry):
+    leaf_input =  base64.decodestring(entry["leaf_input"])
+    (leaf_cert, timestamp, issuer_key_hash) = unpack_mtl(leaf_input)
+    extra_data = base64.decodestring(entry["extra_data"])
+    if issuer_key_hash != None:
+        (precert, extra_data) = extract_precertificate(extra_data)
+        leaf_cert = precert
+    certchain = decode_certificate_chain(extra_data)
+    return ([leaf_cert] + certchain, timestamp, issuer_key_hash)