Wireshark-bugs: [Wireshark-bugs] [Bug 7388] New: SSL decryption doesn't work because of p / q pa
Date: Thu, 21 Jun 2012 05:37:32 -0700 (PDT)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=7388

           Summary: SSL decryption doesn't work because of p / q parameter
                    swap
           Product: Wireshark
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: Major
          Priority: Low
         Component: Wireshark
        AssignedTo: [email protected]
        ReportedBy: [email protected]


Build Information:
TShark 1.9.0 (SVN Rev 43405 from /trunk)

Copyright 1998-2012 Gerald Combs <[email protected]> and contributors.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Compiled (64-bit) with GLib 2.30.3, with libpcap, with libz 1.2.5.1, with POSIX
capabilities (Linux), without SMI, without c-ares, without ADNS, with Lua 5.1,
without Python, with GnuTLS 2.12.18, with Gcrypt 1.4.6, without Kerberos,
without GeoIP.

Running on Linux 3.2.12-gentoo, without locale, with libpcap version 1.1.1,
with
libz 1.2.5.1.

Built using gcc 4.5.3.ssl_privkey_to_sexp

--
If you look at packet-ssl-utils.c you can find in ssl_privkey_to_sexp :

---
    /*
     * note: openssl and gnutls use 'p' and 'q' with opposite meaning:
     * our 'p' must be equal to 'q' as provided from openssl and viceversa
     */

#if
(LIBGNUTLS_VERSION_MAJOR>2)||((LIBGNUTLS_VERSION_MAJOR==2)&&(LIBGNUTLS_VERSION_MINOR>=5))
    p_idx = 3; q_idx = 4;
#else /* versions 2.4.x and older need 'p' and 'q' swapped */
    p_idx = 4; q_idx = 3;
#endif
----


and a bit later another bit :

---
    ssl_get_version(&major, &minor, &patch);

    /* certain versions of gnutls require swap of rsa params 'p' and 'q' */
    if ((major <= 1) && (minor <= 0) && (patch <= 13))
    {
        gcry_mpi_t tmp;
        ssl_debug_printf("ssl_load_key: swapping p and q parameters\n");
        tmp = rsa_params[4];
        rsa_params[4] = rsa_params[3];
        rsa_params[3] = tmp;
    }
---


Despite all those supposed "fixes", on my laptop, despite using a recent GnuTLS
2.12.18 and Gcrypt 1.4.6, p&q are not in the right order, resulting in bad SSL
decryption ... (well, no decryption at all). If I manually force them, then it
works fine.

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