Based on Microsoft's implementation available on github:
Source: https://github.com/Microsoft/PQCrypto-SIDH
Commit: 77044b76181eb61c744ac8eb7ddc7a8fe72f6919
Following changes has been applied
* In intel assembly, use MOV instead of MOVQ:
Intel instruction reference in the Intel Software Developer's Manual
volume 2A, the MOVQ has 4 forms. None of them mentions moving
literal to GPR, hence "movq $rax, 0x0" is wrong. Instead, on 64bit
system, MOV can be used.
* Some variables were wrongly zero-initialized (as per C99 spec)
* Move constant values to .RODATA segment, as keeping them in .TEXT
segment is not compatible with XOM.
* Fixes issue in arm64 code related to the fact that compiler doesn't
reserve enough space for the linker to relocate address of a global
variable when used by 'ldr' instructions. Solution is to use 'adrp'
followed by 'add' instruction. Relocations for 'adrp' and 'add'
instructions is generated by prefixing the label with :pg_hi21:
and :lo12: respectively.
* Enable MULX and ADX. Code from MS doesn't support PIC. MULX can't
reference global variable directly. Instead RIP-relative addressing
can be used. This improves performance around 10%-13% on SkyLake
* Check if CPU supports BMI2 and ADOX instruction at runtime. On AMD64
optimized implementation of montgomery multiplication and reduction
have 2 implementations - faster one takes advantage of BMI2
instruction set introduced in Haswell and ADOX introduced in
Broadwell. Thanks to OPENSSL_ia32cap_P it can be decided at runtime
which implementation to choose. As CPU configuration is static by
nature, branch predictor will be correct most of the time and hence
this check very often has no cost.
* Reuse some utilities from boringssl instead of reimplementing them.
This includes things like:
* definition of a limb size (use crypto_word_t instead of digit_t)
* use functions for checking in constant time if value is 0 and/or
less then
* #define's used for conditional compilation
* Use SSE2 for conditional swap on vector registers. Improves
performance a little bit.
* Fix f2elm_t definition. Code imported from MSR defines f2elm_t type as
a array of arrays. This decays to a pointer to an array (when passing
as an argument). In C, one can't assign const pointer to an array with
non-const pointer to an array. Seems it violates 6.7.3/8 from C99
(same for C11). This problem occures in GCC 6, only when -pedantic
flag is specified and it occures always in GCC 4.9 (debian jessie).
* Fix definition of eval_3_isog. Second argument in eval_3_isog mustn't be
const. Similar reason as above.
* Use HMAC-SHA256 instead of cSHAKE-256 to avoid upstreaming cSHAKE
and SHA3 code.
* Add speed and unit tests for SIKE.
Change-Id: I22f0bb1f9edff314a35cd74b48e8c4962568e330
Kris Kwiatkowski
eb43eca5a8