#20 weak encryption + streaming does not set local CRC value to zero

pmqs · Apr 30, 2024 · 7952c1c · 7952c1c
1 parent 274f75c
commit 7952c1c
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Showing 3 changed files with 10 additions and 11 deletions.
diff --git a/bin/zipdetails b/bin/zipdetails
@@ -2038,8 +2038,17 @@ sub LocalHeader
     my $lastMod = out_V "Modification Time", sub { LastModTime($_[0]) };
 
     my $crc              = out_V "CRC";
+
+    # Weak encryption if
+    # * encrypt flag (bit 0) set in General Purpose Flags
+    # * strong encrypt (bit ) not set in General Purpose Flags
+    # * not using AES encryption (compression method 99)
+    my $weakEncryption = ($gpFlag & ZIP_GP_FLAG_ALL_ENCRYPT) == ZIP_GP_FLAG_ENCRYPTED_MASK &&
+                         $compressedMethod != 99;
+    # Weak encryption uses the CRC value even when streaming is in play.
+    # This conflicts with appnote 6.3.10 section 4.4.4
     warning $FH->tell() - 4, "CRC field should be zero when streaming is enabled"
-        if $streaming && $crc != 0 ;
+        if $streaming && $crc != 0 && ! $weakEncryption;
 
     my $compressedSize   = out_V "Compressed Size";
     # warning $FH->tell(), "Compressed Size should be zero when streaming is enabled";

diff --git a/t/files/0009-infozip/iz-linux-encrypt/stdout b/t/files/0009-infozip/iz-linux-encrypt/stdout
@@ -9,9 +9,6 @@
 0008 Compression Method    0008 (8) 'Deflated'
 000A Modification Time     52988571 (1385727345) 'Sat Apr 24 16:43:34 2021'
 000E CRC                   F90EE7FF (4178503679)
-#
-# WARNING: Offset 0xE: CRC field should be zero when streaming is enabled
-#
 0012 Compressed Size       0000011A (282)
 0016 Uncompressed Size     000001BE (446)
 001A Filename Length       0009 (9)
@@ -82,6 +79,4 @@
 01CC Offset to Central Dir 0000016D (365)
 01D0 Comment Length        0000 (0)
 #
-# Warning Count: 1
-#
 # Done
diff --git a/t/files/0009-infozip/iz-linux-encrypt/stdout-v b/t/files/0009-infozip/iz-linux-encrypt/stdout-v
@@ -9,9 +9,6 @@
 0008 0009 0002 08 00       Compression Method    0008 (8) 'Deflated'
 000A 000D 0004 71 85 98 52 Modification Time     52988571 (1385727345) 'Sat Apr 24 16:43:34 2021'
 000E 0011 0004 FF E7 0E F9 CRC                   F90EE7FF (4178503679)
-#
-# WARNING: Offset 0xE: CRC field should be zero when streaming is enabled
-#
 0012 0015 0004 1A 01 00 00 Compressed Size       0000011A (282)
 0016 0019 0004 BE 01 00 00 Uncompressed Size     000001BE (446)
 001A 001B 0002 09 00       Filename Length       0009 (9)
@@ -86,6 +83,4 @@
 01CC 01CF 0004 6D 01 00 00 Offset to Central Dir 0000016D (365)
 01D0 01D1 0002 00 00       Comment Length        0000 (0)
 #
-# Warning Count: 1
-#
 # Done