Add additional support for SQLCipher v3 and hashes SHA1 and SHA256 and a unit-test

2021-03-26 11:36:41 +01:00
parent 71766dab43
commit 524cb20703
9 changed files with 1166 additions and 156 deletions
@@ -0,0 +1,75 @@
+#!/usr/bin/env perl
+
+##
+## Author......: See docs/credits.txt
+## License.....: MIT
+##
+
+# In a first version I wrote a kernel that followed the original sqlcipher scheme which uses a MAC to verify the integrity (and therefore we knew we had guessed the correct password).
+# But it turns out it's much easier to exploit the sqlite header format, which guarantees 20 zero bytes starting from offset 72.
+# See: https://www.sqlite.org/fileformat.html
+# The advantage is the user doesn't need to guess the MAC hash type and/or pagesize (in case it they customized).
+# The user still needs to know the KDF hash type and iteration count, but they sqlcipher v3 and v4 come with a default for these.
+# We'll check only 12 of 16 bytes from the encrypted block as an optimization so we only need to decrypt one block.
+# Another optimization is that since the scheme uses CBC we do not need to find the correct position of the IV.
+# This position is depending on the pagesize and the KDF hash type (which could be customized).
+# As an alternative, or in case the sqlite header changes, we could also use entropy test.
+# -atom
+
+use strict;
+use warnings;
+
+if (scalar (@ARGV) < 2)
+{
+  print "usage: $0 encrypted.db preset [hash] [iteration]\n\n";
+  print "preset 1 = SQLCIPHER v3\n";
+  print "preset 2 = SQLCIPHER v4\n";
+  print "preset 3 = CUSTOM, please specify hash type (1 = SHA1, 2 = SHA256, 3 = SHA512) and iteration count\n";
+
+  exit -1;
+}
+
+my $db     = $ARGV[0];
+my $preset = $ARGV[1];
+
+my $type = 0;
+my $iter = 0;
+
+if ($preset == 1)
+{
+  $type = 1;
+  $iter = 64000;
+}
+elsif ($preset == 2)
+{
+  $type = 3;
+  $iter = 256000;
+}
+elsif ($preset == 3)
+{
+  $type = $ARGV[2];
+  $iter = $ARGV[3];
+}
+else
+{
+  die "Invalid preset\n";
+}
+
+open (IN, $db) or die ("$db: $!\n");
+
+binmode (IN);
+
+my $data;
+
+if (read (IN, $data, 96) != 96)
+{
+  die "ERROR: Couldn't read data from the file. Maybe incorrect file format?\n";
+}
+
+close (IN);
+
+my $salt = substr ($data,  0, 16);
+my $iv   = substr ($data, 64, 16);
+my $enc  = substr ($data, 80, 16);
+
+printf ("SQLCIPHER*%d*%d*%s*%s*%s\n", $type, $iter, unpack ("H*", $salt), unpack ("H*", $iv), unpack ("H*", $enc));