diff options
| author | Rohan McLure <rmclure@linux.ibm.com> | 2022-11-25 14:42:12 +1100 |
|---|---|---|
| committer | Hugo Landau <hlandau@openssl.org> | 2022-11-28 09:53:00 +0000 |
| commit | 055d029610712a281aed0c23ddd3c8f4dbf40f80 (patch) | |
| tree | e209067bb929f577f697342b6e2499a87a35a717 /crypto/ec | |
| parent | d5e1fe9c04c7eb28e21070e3dfe0d2242504a9bc (diff) | |
Fix accumulated index comments in felem_inv for p521
Comments in felem_inv refer to the logarithm with respect to in of the
element that has just been computed. The last two such annotations are
incorrect. By Fermat's last theorem, we hope to compute in^(p-2) in
GF(2^521-1), as such we expect the final index we reach to be 2^521-3.
CLA: Trivial
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19765)
Diffstat (limited to 'crypto/ec')
| -rw-r--r-- | crypto/ec/ecp_nistp521.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/crypto/ec/ecp_nistp521.c b/crypto/ec/ecp_nistp521.c index 484c42eac9..cc2243a8b3 100644 --- a/crypto/ec/ecp_nistp521.c +++ b/crypto/ec/ecp_nistp521.c @@ -843,9 +843,9 @@ static void felem_inv(felem out, const felem in) felem_reduce(ftmp3, tmp); /* 2^521 - 2^9 */ } felem_mul(tmp, ftmp3, ftmp4); - felem_reduce(ftmp3, tmp); /* 2^512 - 2^2 */ + felem_reduce(ftmp3, tmp); /* 2^521 - 2^2 */ felem_mul(tmp, ftmp3, in); - felem_reduce(out, tmp); /* 2^512 - 3 */ + felem_reduce(out, tmp); /* 2^521 - 3 */ } /* This is 2^521-1, expressed as an felem */ |