nettle-bugs

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Is the gitlab being used or not?
by Gustavo Serra Scalet 09 Apr '17

09 Apr '17

Hi, I noticed there is no merging/update activities on the gitlab website: https://git.lysator.liu.se/nettle/nettle/merge_requests?scope=all&state=all I wonder if it's used. The reason for asking is that I'm willing to integrate a ppc64le-specific implementation using SIMD registers for the SHA-2 algorithm so I would create an Issue to discuss it and then submitting the code as a Merge Request. But only if that's the way for upstreaming code on nettle. If not, please advise if this list can be used. Sorry for using the "nettle-bugs" mailing list, which is not a discussion mailing list. Cheers, Gustavo Serra Scalet

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[PATCH 0/2] Implement RSA-PSS signature scheme
by Daiki Ueno 14 Mar '17

14 Mar '17

From: Daiki Ueno <dueno(a)redhat.com> Hello, This series of patches implements the RSA-PSS signature scheme, as specified in RFC 3447. To keep the interface minimal but to allow TLS 1.3 implementations on top of this, only SHA256/384/512 variants are provided. The prototypes of the top-level functions are as follows: int rsa_pss_shaXXX_sign_digest_tr(const struct rsa_public_key *pub, const struct rsa_private_key *key, void *random_ctx, nettle_random_func *random, size_t salt_length, const uint8_t *salt, const uint8_t *digest, mpz_t s); int rsa_pss_shaXXX_verify_digest(const struct rsa_public_key *key, size_t salt_length, const uint8_t *digest, const mpz_t signature); For MGF, "mask generation function 1" backed by the same hash algorithm is always used, as indicated in [1]. I thought it might make sense to provide more flexible variants, such as rsa_pss_{sign_tr,verify} analogous to rsa_pkcs1_*, but realized that parsing ASN.1 encoded parameters would require extra complexity. Suggestions appreciated. Daiki Ueno (2): Implement PSS encoding functions Add PSS variants for RSA sign/verify functions Makefile.in | 7 +- mgf1-sha256.c | 47 +++++++ mgf1-sha384.c | 47 +++++++ mgf1-sha512.c | 47 +++++++ mgf1.c | 72 +++++++++++ mgf1.h | 70 ++++++++++ nettle-types.h | 3 + nettle.texinfo | 30 +++++ pss-sha256.c | 64 ++++++++++ pss-sha512.c | 90 +++++++++++++ pss.c | 195 ++++++++++++++++++++++++++++ pss.h | 105 +++++++++++++++ rsa-pss-sha256-sign-tr.c | 64 ++++++++++ rsa-pss-sha256-verify.c | 60 +++++++++ rsa-pss-sha512-sign-tr.c | 87 +++++++++++++ rsa-pss-sha512-verify.c | 79 ++++++++++++ rsa-verify.c | 14 ++ rsa.h | 55 ++++++++ testsuite/.test-rules.make | 9 ++ testsuite/Makefile.in | 5 +- testsuite/mgf1-test.c | 23 ++++ testsuite/pss-test.c | 35 +++++ testsuite/rsa-pss-sign-tr-test.c | 268 +++++++++++++++++++++++++++++++++++++++ 23 files changed, 1473 insertions(+), 3 deletions(-) create mode 100644 mgf1-sha256.c create mode 100644 mgf1-sha384.c create mode 100644 mgf1-sha512.c create mode 100644 mgf1.c create mode 100644 mgf1.h create mode 100644 pss-sha256.c create mode 100644 pss-sha512.c create mode 100644 pss.c create mode 100644 pss.h create mode 100644 rsa-pss-sha256-sign-tr.c create mode 100644 rsa-pss-sha256-verify.c create mode 100644 rsa-pss-sha512-sign-tr.c create mode 100644 rsa-pss-sha512-verify.c create mode 100644 testsuite/mgf1-test.c create mode 100644 testsuite/pss-test.c create mode 100644 testsuite/rsa-pss-sign-tr-test.c Footnotes: [1] https://tlswg.github.io/tls13-spec/#signature-algorithms -- 2.9.3

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[PATCH] Make nettle compile with pre-UAL arm assembler.
by Marcus Hoffmann 09 Mar '17

09 Mar '17

See: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0204j/Cjagjj… The pre-UAL instruction is also accepted by modern assemblers. Signed-off-by: Marcus Hoffmann <m.hoffmann(a)cartelsol.com> --- arm/ecc-521-modp.asm | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arm/ecc-521-modp.asm b/arm/ecc-521-modp.asm index c311a89..3fba239 100644 --- a/arm/ecc-521-modp.asm +++ b/arm/ecc-521-modp.asm @@ -91,7 +91,7 @@ PROLOGUE(nettle_ecc_521_modp) adcs F0, F0, F3, lsr #9 C Copy low 9 bits to H, then shift right including carry and H, F0, T0 - rrx F0, F0 + mov F0, F0, rrx lsr F0, F0, #8 C Add in F1 = rp[33], with weight 2^1056 = 2^14 adds F0, F0, F1, lsl #14 -- 2.9.3

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Re: How to pass an IV to the AES 256 encryption/decryption
by Gabriel Ivașcu 04 Mar '17

04 Mar '17

On Sat, Mar 4, 2017 at 2:31 PM, Aapo Talvensaari <aapo.talvensaari(a)gmail.com> wrote: > On Sat, Mar 4, 2017 at 12:18 PM, Gabriel Ivașcu <ivascu.gabriel59(a)gmail.com> > wrote: >> >> Hi, >> >> Can I get some instructions on how to use an IV (initialization >> vector) when doing an AES 256 encryption/decryption? >> >> The AES documentation [0] provides no information on how to pass the >> IV to the AES functions, > > > Please check here: > https://github.com/bungle/lua-resty-nettle/blob/master/lib/resty/nettle/aes… > Thanks for your response, Aapo! I learned eventually that you have to explicitly use the CBC mode [0] if you want to pass an IV, since the AES functions [1] use the ECB mode as default. Also, I found this useful example [2] of how use the CBC mode with Twofish, which I adapted to use AES instead. [0] https://www.lysator.liu.se/~nisse/nettle/nettle.html#CBC [1] https://www.lysator.liu.se/~nisse/nettle/nettle.html#AES [2] https://stackoverflow.com/questions/33003118/nettle-twofish-cbc Regards, Gabriel

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How to pass an IV to the AES 256 encryption/decryption
by Gabriel Ivașcu 04 Mar '17

04 Mar '17

Hi, Can I get some instructions on how to use an IV (initialization vector) when doing an AES 256 encryption/decryption? The AES documentation [0] provides no information on how to pass the IV to the AES functions. [0] https://www.lysator.liu.se/~nisse/nettle/nettle.html#AES Thank you, Gabriel

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lock-free random generator
by Nikos Mavrogiannopoulos 28 Feb '17

28 Feb '17

Hi, One of the items that have been on my todo-list after discussing with application writers of multi-threaded applications (mainly servers), is addressing the issue of synchronization for the random generator. Currently gnutls provides a "central" random generator based on yarrow (for keys) and salsa20 (for nonces) primitives, and it is thread safe by utilizing mutexes over it. An application that has more than 100-200 threads is most likely to spend more time in synchronization rather than the random generator itself. A solution to that would be to provide a thread-local random generator which will work lock-free, at the cost of additional memory per-thread -around 600-700 bytes for the current generator-. I have an experimental patch set, implementing this idea at: https://gitlab.com/gnutls/gnutls/merge_requests/259 On the patch above, the additional cost per thread will only be for threads actually utilizing gnutls, and in particular the random generator, as the required memory will be allocated after the first call to gnutls_rnd() by the thread. Are there any objections on such an enhancement to gnutls, or suggestions on how such a lock-free random generator could be improved (in terms of memory utilization for example)? regards, Nikos

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detecting sha1 collisions
by Nikos Mavrogiannopoulos 24 Feb '17

24 Feb '17

Hi, There is a sha1 collision detection library at: https://github.com/cr-marcstevens/sha1collisiondetection Given that algorithms like sha1 are notoriously hard to phase out, does it make sense for nettle to add support for collision detection, in effect giving applications the option to switch to a mode where a known to be insecure hash is enabled, but with such collision detection mitigations in place. Does something like the above library make sense to be added to nettle? regards, Nikos

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Google OSS-Fuzz and Google Wycheproof for Nettle?
by Joachim Strömbergson 18 Jan '17

18 Jan '17

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Aloha! Ran into the Google OSS-Fuzz project. The project provides the Google compute power for oss projects to run fuzzing on the code. Judging by the list of projects libraries such as GnuTLS, OpenSSL, LibSSH and Curl are being tested. Would it be worthwile to try and get Nettle accepted as a project? Has anybody looked at OSS-Fuzz for Nettle? https://github.com/google/oss-fuzz https://github.com/google/oss-fuzz/tree/master/projects Another imho interesting project Google project is Wycheproof. The project tests crypto libraries against known attacks/issues such as invalid curve attacks, biased nonces in digital signature schemes etc. Right now there are 80 tests. The code is in Java and I don't know how easy/hard it would be to connect Nettle to the test system. But at least one could look at the tests and implement the same tests for Nettle. https://github.com/google/wycheproof https://github.com/google/wycheproof/tree/master/java/com/google/security/w… Has anybody looked at Wycheproof for testing Nettle? - -- Med vänlig hälsning, Yours Joachim Strömbergson - Alltid i harmonisk svängning. ======================================================================== Joachim Strömbergson Secworks AB joachim(a)secworks.se ======================================================================== -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBCAAGBQJYf23WAAoJEF3cfFQkIuyNKVgP/1R08TRJCYlMR2LsN3HxEJLj P6ZdksGL1A6jWHlSV7iN5UNJKWGXmF3mJ3mo4AgBZD1Xe6t1S6cpn4RkyFgc51xa +JDJgEeMhxGZptfCSjwktnoBo7T6WYZzPlw2SghD9ur6D2wiJ71K/P6LpD+3omLj BrUbaihPvRKMTPlkZi33cgjj9L1ni9LPf1I7Ir1GibtrT2NNZKZ3l2pZ5dHt7sr5 5ZtXlQZPcIlUJkpA0EUUgV5vnXMr4MxR4NFphY3xRh562ffILV0HPO+bjjPJCDo/ qbLdq0jeDXxHoIjrhUgCKWZ+03zvE+Qi+3iBiGziOS+NC92nXOnni9ehfmHrvEe5 HDBZmtO8otkU0WuUt88ovjoOKtjkvKV05gfNhwDDLSGL2NlYllAsF/13h5Ewsi2f huHdo9QPO9gUDwMDfjXt58zGmlGipju3ybSj1K9Ly/9uD1ep/yLXA/L6w2iFZ7ga XPBf0StjDLwF7yMgmhXhhhKAbV0+SgmdghG1z4D5jEVnZRhMpKN4KUs9seS8wznL XyqhWxC/swiKP1BEMbpIW9XZ3hJaMb8bKqObv5BWXscrlV7aStv9o5CFmgSeaPBr AJHXk+w6Q1dXbaVp+Tb4uhzNBVyHcLkiitQYITW8mg6SwoFclra3oh2Es2XZU1c9 h6K29UbA7UaGyum5ZDED =yz1M -----END PGP SIGNATURE-----

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Subtle ABI problem with nettle_hashes
by nisse＠lysator.liu.se 13 Jan '17

13 Jan '17

The idea of the interface /* null-terminated list of digests implemented by this version of nettle */ extern const struct nettle_hash * const nettle_hashes[]; was that the size of the array isn't part of the ABI; a new Nettle version should be able to extend it with more entries, without breaking the ABI. However, I've recently learnt that it does break, in a subtle way. (See https://bugs.gentoo.org/show_bug.cgi?id=601512 and http://trofi.github.io/posts/195-dynamic-linking-ABI-is-hard.html). The problematic case is a traditional non-PIC executable linking with a nettle shared library; in this post, I care exclusively about this case. All symbol references in the executable are resolved at link time, and at load time it is mapped at a fixed address (traditionally 0, I don't know if current systems skip the first page), without any relocations. Now, if the executable links with libnettle.so, and contains a reference to the symbol nettle_hashes, the address where nettle.so is going to be mapped isn't known at link time? So how can the executable refer to it without load-time relocation of its references? The linker solves that problem using the curious relocation type R_X86_64_COPY. What the linker does is that it allocates space for a copy of the data in the BSS segment of the executable, and resolve all references to point to that copy. At the time libnettle.so is loaded, the list in the library is copied (after relocating it, but that's a minor complication in this context) to the space in the BSS. I imagine the dynamic linker also adjusts the pointers in libnettle.so's GOT table to refer to the copy rather than the original. Now the problem is that the allocation in the BSS segment, as well as the copying operation, are based on the size of the data object as recorded in the version of libnettle.so available at the time the executable was linked. If the array size is larger in the version of libnettle.so actally loaded, the copy operation is truncates it, which is particularly bad when it's NULL-terminated. So the array size, which was intended to not be part of the ABI, creeps into the ABI. So what to do about this? We have to break the ABI, but I'd prefer if we keep the API unchanged. Some alternatives: 1. Define nettle_hashesp as a constant pointer to the current nettle_hashes list, and #define nettle_hashes (*nettle_hashesp) Then nettle_hashesp will still get a R_X86_64_COPY relocation, but now the size is always a single pointer, regardless of the array size. At load time, it will be set to point directly to the list in the data segment of the loaded libnettle.so. 2. Define a function get_nettle_hashes returning a pointer to the list, and #define nettle_hashes (get_nettle_hashes()) In this case, the indirection is via a PLT entry in the executable. 3. Define the array with a size explicitly part of the ABI, extern const struct nettle_hash * const nettle_hashes[17]; Add a some reasonable number of reserved NULL entries at the end, and make an ABI break whenever we run out of reserved places and have to increase the size. We also have other public data, e.g., individual nettle_hash structs, like extern const struct nettle_hash nettle_sha256; These will also get a R_X86_64_COPY relocation if referenced (and all internal references within libnettle.so will be relocated to the copy in the executable's BSS, I guess). But that's less of a problem, since the size and layout is already part of the ABI. More problematic are the objects declared in ecc-curve.h; the size and layout of struct ecc_curve was intended to be an implementation detail, not part of the ABI, but isn't, when R_X86_64_COPY is involved. Advice appreciated. I'd also like to hear if anyone on the list knows how these things work with windows dlls. I've read sometime that exporting data (in contrast to functions) from a dll is extra tricky, but I don't remember any details. If we make any changes to fix the exported-data issues with ELF, it would be good if we could ensure that we solve any related problems for libnettle.dll too. I understand why R_X86_64_COPY is needed, but it works in a way that was pretty counter-intutive to me. The effect is, more or less, that the library's data is *statically* linked into the executable. And then initialized at load time based on the contents of the loaded library. And we then get a mix of statically linked and dynamically linked parts which might originate in different versions of the library. It would be prettier if we could force the executable to always access library data via GOT (like it works for PIC code), and never use R_X86_64_COPY. But I guess that has to be known at code generation time, and likely too late to fixup at link time, which is when we know which external data objects are defined by some shared library, and which aren't. But if anyone knows how to fix the issue in this way, I'd be delighted. Regards, /Niels -- Niels Möller. PGP-encrypted email is preferred. Keyid 368C6677. Internet email is subject to wholesale government surveillance.

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Do we still need to support compilers without stdint.h?
by nisse＠lysator.liu.se 05 Jan '17

05 Jan '17

Hi, the configure macro AX_CREATE_STDINT_H and the generated nettle-stdint.h file was added more than a decade ago, when stdint.h (and c99) were somewhat new. Do we still need this? Is anyone building nettle with C compilers which don't provide stdint.h? Regards, /Niels -- Niels Möller. PGP-encrypted email is preferred. Keyid 368C6677. Internet email is subject to wholesale government surveillance.

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