boringssl/third_party/fiat
Joshua Liebow-Feeser 8c7c6356e6 Support symbol prefixes
- In base.h, if BORINGSSL_PREFIX is defined, include
  boringssl_prefix_symbols.h
- In all .S files, if BORINGSSL_PREFIX is defined, include
  boringssl_prefix_symbols_asm.h
- In base.h, BSSL_NAMESPACE_BEGIN and BSSL_NAMESPACE_END are
  defined with appropriate values depending on whether
  BORINGSSL_PREFIX is defined; these macros are used in place
  of 'namespace bssl {' and '}'
- Add util/make_prefix_headers.go, which takes a list of symbols
  and auto-generates the header files mentioned above
- In CMakeLists.txt, if BORINGSSL_PREFIX and BORINGSSL_PREFIX_SYMBOLS
  are defined, run util/make_prefix_headers.go to generate header
  files
- In various CMakeLists.txt files, add "global_target" that all
  targets depend on to give us a place to hook logic that must run
  before all other targets (in particular, the header file generation
  logic)
- Document this in BUILDING.md, including the fact that it is
  the caller's responsibility to provide the symbol list and keep it
  up to date
- Note that this scheme has not been tested on Windows, and likely
  does not work on it; Windows support will need to be added in a
  future commit

Change-Id: If66a7157f46b5b66230ef91e15826b910cf979a2
Reviewed-on: https://boringssl-review.googlesource.com/31364
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
Reviewed-by: David Benjamin <davidben@google.com>
2018-09-06 20:07:52 +00:00
..
BUILD.gn Add files in third_party/fiat for Chromium to pick up. 2018-01-10 22:02:03 +00:00
curve25519_tables.h Use 51-bit limbs from fiat-crypto in 64-bit. 2018-01-23 22:25:07 +00:00
curve25519.c Document that ED25519_sign only fails on allocation failure 2018-08-29 18:35:12 +00:00
internal.h Remove x86_64 x25519 assembly. 2018-02-01 21:44:58 +00:00
LICENSE
make_curve25519_tables.py Use 51-bit limbs from fiat-crypto in 64-bit. 2018-01-23 22:25:07 +00:00
METADATA third_party: re-format METATADA files 2018-02-27 19:57:12 +00:00
p256.c Clear mallocs in ec_wNAF_mul. 2018-04-27 19:44:58 +00:00
README.chromium Add files in third_party/fiat for Chromium to pick up. 2018-01-10 22:02:03 +00:00
README.md Use 51-bit limbs from fiat-crypto in 64-bit. 2018-01-23 22:25:07 +00:00

Fiat

Some of the code in this directory is generated by Fiat and thus these files are licensed under the MIT license. (See LICENSE file.)

Curve25519

To generate the field arithmetic procedures in curve25519.c from a fiat-crypto checkout (as of 7892c66d5e0e5770c79463ce551193ceef870641), run make src/Specific/solinas32_2e255m19_10limbs/femul.c (replacing femul with the desired field operation). The "source" file specifying the finite field and referencing the desired implementation strategy is src/Specific/solinas32_2e255m19_10limbs/CurveParameters.v, specifying roughly "unsaturated arithmetic modulo 2^255-19 using 10 limbs of radix 2^25.5 in 32-bit unsigned integers with a single carry chain and two wraparound carries" where only the prime is considered normative and everything else is treated as "compiler hints".

The 64-bit implementation uses 5 limbs of radix 2^51 with instruction scheduling taken from curve25519-donna-c64. It is found in src/Specific/solinas64_2e255m19_5limbs_donna.

P256

To generate the field arithmetic procedures in p256.c from a fiat-crypto checkout, run make src/Specific/montgomery64_2e256m2e224p2e192p2e96m1_4limbs/femul.c. The corresponding "source" file is src/Specific/montgomery64_2e256m2e224p2e192p2e96m1_4limbs/CurveParameters.v, specifying roughly "64-bit saturated word-by-word Montgomery reduction modulo 2^256 - 2^224 + 2^192 + 2^96 - 1". Again, everything except for the prime is untrusted. There is currently a known issue where fesub.c for p256 does not manage to complete the build (specialization) within a week on Coq 8.7.0. https://github.com/JasonGross/fiat-crypto/tree/3e6851ddecaac70d0feb484a75360d57f6e41244/src/Specific/montgomery64_2e256m2e224p2e192p2e96m1_4limbs does manage to build that file, but the work on that branch was never finished (the correctness proofs of implementation templates still apply, but the now abandoned prototype specialization facilities there are unverified).

Working With Fiat Crypto Field Arithmetic

The fiat-crypto readme https://github.com/mit-plv/fiat-crypto#arithmetic-core contains an overview of the implementation templates followed by a tour of the specialization machinery. It may be helpful to first read about the less messy parts of the system from chapter 3 of http://adam.chlipala.net/theses/andreser.pdf. There is work ongoing to replace the entire specialization mechanism with something much more principled https://github.com/mit-plv/fiat-crypto/projects/4.