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| author | Vitaly Chikunov <vt@altlinux.org> | 2018-11-11 20:40:02 +0300 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2018-11-16 14:11:04 +0800 |
| commit | 3da2c1dfdb802b184eea0653d1e589515b52d74b (patch) | |
| tree | 2f5689d4508f993fc477ce5dbdb35c6e76d6ff8b /virt | |
| parent | 8a5a79d5556b822143b4403fc46068d4eef2e4e2 (diff) | |
| download | lwn-3da2c1dfdb802b184eea0653d1e589515b52d74b.tar.gz lwn-3da2c1dfdb802b184eea0653d1e589515b52d74b.zip | |
crypto: ecc - regularize scalar for scalar multiplication
ecc_point_mult is supposed to be used with a regularized scalar,
otherwise, it's possible to deduce the position of the top bit of the
scalar with timing attack. This is important when the scalar is a
private key.
ecc_point_mult is already using a regular algorithm (i.e. having an
operation flow independent of the input scalar) but regularization step
is not implemented.
Arrange scalar to always have fixed top bit by adding a multiple of the
curve order (n).
References:
The constant time regularization step is based on micro-ecc by Kenneth
MacKay and also referenced in the literature (Bernstein, D. J., & Lange,
T. (2017). Montgomery curves and the Montgomery ladder. (Cryptology
ePrint Archive; Vol. 2017/293). s.l.: IACR. Chapter 4.6.2.)
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
Cc: kernel-hardening@lists.openwall.com
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'virt')
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