From 1ed44e7bd683d5a4543553e4332a1d51fc0d803b Mon Sep 17 00:00:00 2001
From: Philipp Gesang <philipp.gesang@intra2net.com>
Date: Mon, 14 Aug 2017 17:24:56 +0200
Subject: [PATCH] catch bad parameter version in header

---
 deltatar/crypto.py  |    4 ++--
 deltatar/tarfile.py |   12 +++++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/deltatar/crypto.py b/deltatar/crypto.py
index 92c0d8b..930d1f9 100755
--- a/deltatar/crypto.py
+++ b/deltatar/crypto.py
@@ -574,8 +574,8 @@ def kdf_by_version (paramversion=None, defs=None):
     if paramversion is not None:
         defs = ENCRYPTION_PARAMETERS.get(paramversion, None)
     if defs is None:
-        raise ValueError ("no encryption parameters for version %r"
-                % paramversion)
+        raise InvalidParameter ("no encryption parameters for version %r"
+                                % paramversion)
     (kdf, params) = defs["kdf"]
     fn = None
     if kdf == "scrypt" : fn = kdf_scrypt
diff --git a/deltatar/tarfile.py b/deltatar/tarfile.py
index 2629e44..526c1ac 100644
--- a/deltatar/tarfile.py
+++ b/deltatar/tarfile.py
@@ -872,7 +872,13 @@ class _Stream:
                                            % (self.enccounter, iv))
             self.lasthdr   = lasthdr
             self.remainder = hdr ["ctsize"] # distance to next header
-            self.encryption.next (hdr)
+            try:
+                self.encryption.next (hdr)
+            except crypto.InvalidParameter as exn:
+                raise DecryptionError ("Crypto.next(): error “%s” "
+                                       "processing %r at pos %d"
+                                       % (exn, self.fileobj, lasthdr)) \
+                      from exn
 
         return True
 
@@ -1011,7 +1017,7 @@ class _Stream:
         """
         c = len(self.buf)
         t = [self.buf]
-        good_crypto = 0
+        good_crypto = len (t)
         while c < size:
             todo = size
             if self.arcmode & ARCMODE_ENCRYPT:
@@ -1022,7 +1028,7 @@ class _Stream:
                             buf = None
                             break # while
                     except DecryptionError:
-                        if self.tolerant:
+                        if self.tolerant is True:
                             self.buf = b"".join (t [good_crypto:])
                             return b"".join (t [:good_crypto])
                         raise
-- 
1.7.1