The files no longer need to be patched because fiat-crypto now has its
own copy of our value barrier. It does, however, require syncing our
NO_ASM define with fiat's.
fiat-crypto is now licensed under any of MIT, BSD 1-clause, or Apache 2.
I've stuck with the MIT one as that's what we were previously importing.
No measurable perf difference before/after this CL, with GCC or Clang on
x86_64.
Change-Id: I2939fd517de37aabdea3ead49150135200a1b112
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52045
Reviewed-by: Adam Langley <agl@google.com>
Description:
Mark Wooden and Franck Rondepierre noted that the square-root-mod-p
operations used in the EdDSA RFC (RFC 8032) can be simplified. For
Ed25519, instead of computing u*v^3 * (u * v^7)^((p-5)/8), we can
compute u * (u*v)^((p-5)/8). This saves 3 multiplications and 2
squarings. For more details (including a proof), see the following
message from the CFRG mailing list:
https://mailarchive.ietf.org/arch/msg/cfrg/qlKpMBqxXZYmDpXXIx6LO3Oznv4/
Testing:
Build and run the Ed25519 tests:
mkdir build
cd build
cmake -GNinja ..
ninja && ./crypto/crypto_test --gtest_filter="Ed25519Test*"
Numerical testing of the square-root computation can be done using the
following sage script:
def legendre(x,p):
return kronecker(x,p)
# Ed25519
p = 2**255-19
# -1 is a square
if legendre(-1,p)==1:
print("-1 is a square")
# 2 is a non-square
if legendre(2,p)==-1:
print("2 is a non-square")
# 2 is a generator
# this can be checked by factoring p-1
# and then showing 2**((p-1)/q) != 1 (mod p)
# for all primes q dividing p-1.
# suppose u/v is a square.
# to compute one of its square roots, find x such that
# x**4 == (u/v)**2 .
# this implies
# x**2 == u/v, or
# x**2 == -(u/v) ,
# which implies either x or i*x is a square-root of u/v (where i is a square root of -1).
# we can take x equal to u * (u*v)**((p-5)/8).
g = 2
s = p>>2 # s = (p-1)/4
i = power_mod(g, s, p)
t = p>>3 # t = (p-5)/8
COUNT = 1<<18
while COUNT > 0:
COUNT -= 1
r = randint(0,p-1) # r = u/v
v = randint(1,p-1)
u = mod(r*v,p)
# compute x = u * (u*v)**((p-5)/8)
w = mod(u*v,p)
x = mod(u*power_mod(w, t, p), p)
# check that x**2 == r, or (i*x)**2 == r, or r is not a square
rr = power_mod(x, 2, p)
if rr==r:
continue
rr = power_mod(mod(i*x,p), 2, p)
if rr==r:
continue
if legendre(r,p) != 1:
continue
print("failure!")
exit()
print("passed!")
Change-Id: Iaa284d3365dd8c9fa18a4584121013f05a3f4cc6
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50965
Reviewed-by: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
These symbols were not marked OPENSSL_EXPORT, so they weren't really
usable externally anyway. They're also very sensitive to various build
configuration toggles, which don't always get reflected into projects
that include our headers. Move them to crypto/internal.h.
Change-Id: I79a1fcf0b24e398d75a9cc6473bae28ec85cb835
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50846
Reviewed-by: Adam Langley <agl@google.com>
If I perturb kOrder in the malleability check, our and Wycheproof's
tests don't easily notice. This adds some tests with s above and below
the order. EdDSA hashes the public key with the message, which
frustrates constructing actual boundary cases. Instead, these inputs
were found by generating many signatures.
This isn't ideal, but it is sensitive to the most significant 32 bits.
Change-Id: I7fc03758ab97650d0e94478f355ea7085ae0559a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/44346
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
David Benjamin
James Muir
Peter Foley
Adam Langley