nettle-bugs March 2024

nettle-bugs@lists.lysator.liu.se

6 participants
10 discussions

[PATCH 0/2] Add optimized powerpc64 assembly for SHA2
by Eric Richter 17 Apr '24

17 Apr '24

This set introduces an optimized powerpc64 assembly implementation for SHA256 and SHA512. This have been derived from BSD-2-Clause licensed code authored by IBM, originally released in the IBM POWER Cryptography Reference Implementation project[1], modified to work in Nettle, contributed under the GPL license. Development of this new implementation targetted POWER 10, however supports the POWER 8 ISA and above. The following commits provide the performance data I recorded on POWER 10, though similar improvements can be found on P8/P9. As an aside: I have tested this patch set on POWER 8 and POWER 10 hardware running little-endian linux distributions, however I have not yet been able to test on a big-endian distro. I can confirm however that the original source in IPCRI does compile and pass tests for both little and big endian via qemu-user, so spare human error in deriving the version for Nettle, it is expected to be functional. [1] https://github.com/ibm/ipcri Eric Richter (2): powerpc64: Add optimized assembly for sha256-compress-n powerpc64: Add optimized assembly for sha512-compress-n powerpc64/p8/sha256-compress-n.asm | 339 ++++++++++++++++++++++++++++ powerpc64/p8/sha512-compress.asm | 345 +++++++++++++++++++++++++++++ 2 files changed, 684 insertions(+) create mode 100644 powerpc64/p8/sha256-compress-n.asm create mode 100644 powerpc64/p8/sha512-compress.asm -- 2.43.0

2 7

ppc64 micro optimization
by Niels Möller 14 Apr '24

14 Apr '24

In preparing for merging the gcm-aes "stitched" implementation, I'm reviewing the existing ghash code. WIP branch "ppc-ghash-macros. I've introduced a macro GHASH_REDUCE, for the reduction logic. Besides that, I've been able to improve scheduling of the reduction instructions (adding in the result of vpmsumd last seems to improve parallelism, some 3% speedup of gcm_update on power10, benchmarked on cfarm120). I've also streamlined the way load offsets are used, and trimmed the number of needed vector registers slightly. For the AES code, I've merged the new macros (I settled on the names OPN_XXY and OPN_XXXY), no change in speed expected from that change. I've also tried to understand the differenct between AES encrypt and decrypt, where decrypt is much slower, and uses an extra xor instruction in the round loop. I think the reason for that is that other AES implementations (including x86_64 and arm64 instructions, and Nettle's C implementation) expect the decryption subkeys to be transformed via the AES "MIX_COLUMN" operation, see https://gitlab.com/gnutls/nettle/-/blob/master/aes-invert-internal.c?ref_ty… While the powerpc64 vncipher instruction really wants the original subkeys, not transformed. So on power, it would be better to have a _nettle_aes_invert that is essentially a memcpy, and then the aes decrypt assembly code could be reworked without the xors, and run at exactly the same speed as encryption. Current _nettle_aes_invert also changes the order of the subkeys, with a FIXME comment suggesting that it would be better to update the order keys are accessed in the aes decryption functions. Regards, /Niels -- Niels Möller. PGP key CB4962D070D77D7FCB8BA36271D8F1FF368C6677. Internet email is subject to wholesale government surveillance.

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additional API for SHAKE streaming read
by Daiki Ueno 14 Apr '24

14 Apr '24

Hello, When I'm trying to implement ML-KEM (Kyber), I realized that the current API for SHAKE (sha3_256_shake) is a bit too limited: while ML-KEM uses SHAKE128 as a source of pseudorandom samples[1], the the current API requires the total number of bytes are determined prior to the call, and after the call the hash context is reset. Here I propose adding a couple of helper functions to support such streaming use-case: sha3_256_shake_pad to process the final block, and sha3_256_shake_read to read the digest from the current state without resetting the context. With those functions, one could write a streaming read interface as attached. What do you think? The actual code changes can be found at: https://git.lysator.liu.se/nettle/nettle/-/merge_requests/61 I also have a SHAKE128 implementation with analogous API, which I will post later. Regards, Footnotes: [1] https://bwesterb.github.io/draft-schwabe-cfrg-kyber/draft-cfrg-schwabe-kybe… -- Daiki Ueno #include "sha3.h" #include <stdio.h> struct shake_reader { struct sha3_256_ctx ctx; uint8_t buf[SHA3_256_BLOCK_SIZE]; size_t offset; }; static void shake_reader_init (struct shake_reader *reader) { sha3_256_init (&reader->ctx); reader->offset = sizeof(reader->buf); } static void shake_reader_read (struct shake_reader *reader, size_t length, uint8_t *digest) { while (length > 0) { while (reader->offset < sizeof(reader->buf)) { *digest++ = reader->buf[reader->offset++]; length--; if (!length) return; } if (reader->offset == sizeof(reader->buf)) { sha3_256_shake_read (&reader->ctx, sizeof(reader->buf), reader->buf); sha3_permute (&reader->ctx.state); reader->offset = 0; } } } int main (void) { struct shake_reader reader; uint8_t buf[3]; size_t n = 0; shake_reader_init (&reader); sha3_256_update (&reader.ctx, 0, NULL); sha3_256_shake_pad (&reader.ctx); while (n < 256) { shake_reader_read (&reader, sizeof(buf), buf); int d1 = buf[0] + 256 * (buf[1] % 16); int d2 = (buf[1] >> 4) + 16 * buf[2]; if (d1 < 3329) { printf ("%d\n", d1); n++; } if (n == 256) break; if (d2 < 3329) { printf ("%d\n", d2); n++; } } return 0; }

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Issue tracker
by Niels Möller 29 Mar '24

29 Mar '24

Hi, I've enabled the issue tracker at https://git.lysator.liu.se/nettle/nettle/-/issues, and filed a few issues for old TODO items, most of which imply ABI and/or API changes. Feel free to file aditional issues for bugs, feature requests, or to track work you are doing or planning. My intention is to (i) keep track of desirable or in-progress changes, and (ii) use for release planning, e.g., use a tag or "milestone" to attach to issues that we want to be included in the next release, similar to how misc/plan.html has been use for some of the releases in the past. Regards, /Niels -- Niels Möller. PGP key CB4962D070D77D7FCB8BA36271D8F1FF368C6677. Internet email is subject to wholesale government surveillance.

1 0

Naming for names in struct nettle_hash
by Niels Möller 28 Mar '24

28 Mar '24

Hi, I've got a bug report that sha512_224 and sha512_256 are missing in the list returned by nettle_get_hashes, and I'm about to add them. But then there's a question of naming convention. Currently, the extern const struct nettle_hash nettle_sha512_256; includes a name field set to the string "sha512-256", which is somewhat inconsistent with, e.g., the struct nettle_sha3_256 which includes the name "sha3_256". Should I just change this (patch below)? Honestly, I haven't given much thought to the conventions used here, but perhaps it makes the most sense that naming match the names of corresponding C symbols (with underscore rather than dash)? Regards, /Niels diff --git a/nettle-meta-hashes.c b/nettle-meta-hashes.c index 4d421182..2245dfb7 100644 --- a/nettle-meta-hashes.c +++ b/nettle-meta-hashes.c @@ -49,6 +49,8 @@ const struct nettle_hash * const _nettle_hashes[] = { &nettle_sha256, &nettle_sha384, &nettle_sha512, + &nettle_sha512_224, + &nettle_sha512_256, &nettle_sha3_224, &nettle_sha3_256, &nettle_sha3_384, diff --git a/sha512-224-meta.c b/sha512-224-meta.c index 24c42bfc..f3751e14 100644 --- a/sha512-224-meta.c +++ b/sha512-224-meta.c @@ -39,7 +39,7 @@ const struct nettle_hash nettle_sha512_224 = { - "sha512-224", sizeof(struct sha512_ctx), + "sha512_224", sizeof(struct sha512_ctx), SHA512_224_DIGEST_SIZE, SHA512_224_BLOCK_SIZE, (nettle_hash_init_func *) sha512_224_init, diff --git a/sha512-256-meta.c b/sha512-256-meta.c index 37d17c35..181f2874 100644 --- a/sha512-256-meta.c +++ b/sha512-256-meta.c @@ -39,7 +39,7 @@ const struct nettle_hash nettle_sha512_256 = { - "sha512-256", sizeof(struct sha512_ctx), + "sha512_256", sizeof(struct sha512_ctx), SHA512_256_DIGEST_SIZE, SHA512_256_BLOCK_SIZE, (nettle_hash_init_func *) sha512_256_init, diff --git a/testsuite/meta-hash-test.c b/testsuite/meta-hash-test.c index 6a15e7db..ec4e0d1e 100644 --- a/testsuite/meta-hash-test.c +++ b/testsuite/meta-hash-test.c @@ -16,6 +16,8 @@ const char* hashes[] = { "sha256", "sha384", "sha512", + "sha512_224", + "sha512_256", "sha3_224", "sha3_256", "sha3_384", -- Niels Möller. PGP key CB4962D070D77D7FCB8BA36271D8F1FF368C6677. Internet email is subject to wholesale government surveillance.

1 1

Adding MD5/SHA1 support to RSA OAEP
by Hans Leidekker 27 Mar '24

27 Mar '24

Hello, I noticed the arrival of an RSA OAEP implementation in GnuTLS and wanted to use that to support the algorithm in Wine. Windows supports it using the old MD5 and SHA1 hash functions, so my question is: would you accept a patch like below that adds these hashes?

2 4

HPKE ready for Merge!
by Ajit singh 24 Mar '24

24 Mar '24

Hi all, I trust this message finds you well. Notably, HPKE has already been successfully implemented, and now your prompt attention is sought for the critical review and merging of the MR into the main branch of Nettle. As encrypted client hello(ECH) also relies on HPKE, your swift action is highly appreciated. HPKE MR Link:https://git.lysator.liu.se/nettle/nettle/-/merge_requests/27 Thanks, Ajit

3 4

Relax blocking requirement of gcm_update?
by Niels Möller 10 Mar '24

10 Mar '24

While looking at extended tests of the aead update function (for the associated data), I stumbled on a restriction of gcm_update that is different from most (all?) other update functions in Nettle. According to the docs, -- Function: void gcm_update (struct gcm_ctx *CTX, const struct gcm_key *KEY, size_t LENGTH, const uint8_t *DATA) Provides associated data to be authenticated. If used, must be called before ‘gcm_encrypt’ or ‘gcm_decrypt’. All but the last call for each message _must_ use a length that is a multiple of the block size. Would it be worthwhile to drop the restriction of the last sentence, and allow all calls to gcm_update to use any size? This requirement may be particularly surprising when using nettle_aead; then gcm has different requirements for the update function than all other aead algorithms. I think that might be doable without any ABI break, by the following hack: reuse the ctr field of struct gcm_context as a block buffer, while processing the associated data. The ctr field is clearly needed also for encrypt/decrypt, but we could move initialization for that purpose from gcm_set_iv to the first call to encrypt/decrypt. Regards, /Niels -- Niels Möller. PGP key CB4962D070D77D7FCB8BA36271D8F1FF368C6677. Internet email is subject to wholesale government surveillance.

2 3

Add RSA-OAEP encryption/decryption to Nettle
by Nicolas Mora 09 Mar '24

09 Mar '24

Hello, I've made a new Merge Request in the nettle gitlab repo to provide RSA-OAEP encryption and decryption: https://git.lysator.liu.se/nettle/nettle/-/merge_requests/20 It adds 2 new functions: int pkcs1_oaep_encrypt (size_t key_size, void *random_ctx, nettle_random_func *random, size_t hlen, size_t label_length, const uint8_t *label, size_t message_length, const uint8_t *message, mpz_t m); int pkcs1_oaep_decrypt (size_t key_size, const mpz_t m, size_t hlen, size_t label_length, const uint8_t *label, size_t *length, uint8_t *message); The parameter hlen is the output length of the SHA function used for masking data: - SHA1_DIGEST_SIZE - SHA256_DIGEST_SIZE - SHA384_DIGEST_SIZE - SHA512_DIGEST_SIZE Is it possible to get feedback for this MR and eventually push it to the master branch? Thanks in advance /Nicolas

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Support for ML-KEM (Kyber)
by Daiki Ueno 04 Mar '24

04 Mar '24

Hello, I created a draft patch to support ML-KEM (a post-quantum key encapsulation mechanism, formerly known as Kyber)[1], based on the explanation in the corresponding IETF draft[2]. There are probably a lot of rooms for improvements (performance, side-channel safety), but I'm sharing the code at: https://git.lysator.liu.se/nettle/nettle/-/merge_requests/62 Any comments or suggestions would be appreciated. Footnotes: [1] https://csrc.nist.gov/pubs/fips/203/ipd [2] https://datatracker.ietf.org/doc/draft-cfrg-schwabe-kyber/ Regards, -- Daiki Ueno

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nettle-bugs March 2024