diff options
| author | Billy Brumley <bbrumley@gmail.com> | 2019-02-02 10:53:29 +0200 |
|---|---|---|
| committer | Nicola Tuveri <nic.tuv@gmail.com> | 2019-02-20 19:54:19 +0200 |
| commit | 48e82c8e22f8ac16ad0666d99172f6dbaf33953a (patch) | |
| tree | 7d86658594b9a9800f1eefae0a926bf403c5db3c /CHANGES | |
| parent | 70fa3aa108320d15536228656b120d3e08de0e40 (diff) | |
SCA hardening for mod. field inversion in EC_GROUP
This commit adds a dedicated function in `EC_METHOD` to access a modular
field inversion implementation suitable for the specifics of the
implemented curve, featuring SCA countermeasures.
The new pointer is defined as:
`int (*field_inv)(const EC_GROUP*, BIGNUM *r, const BIGNUM *a, BN_CTX*)`
and computes the multiplicative inverse of `a` in the underlying field,
storing the result in `r`.
Three implementations are included, each including specific SCA
countermeasures:
- `ec_GFp_simple_field_inv()`, featuring SCA hardening through
blinding.
- `ec_GFp_mont_field_inv()`, featuring SCA hardening through Fermat's
Little Theorem (FLT) inversion.
- `ec_GF2m_simple_field_inv()`, that uses `BN_GF2m_mod_inv()` which
already features SCA hardening through blinding.
From a security point of view, this also helps addressing a leakage
previously affecting conversions from projective to affine coordinates.
This commit also adds a new error reason code (i.e.,
`EC_R_CANNOT_INVERT`) to improve consistency between the three
implementations as all of them could fail for the same reason but
through different code paths resulting in inconsistent error stack
states.
Co-authored-by: Nicola Tuveri <nic.tuv@gmail.com>
(cherry picked from commit e0033efc30b0f00476bba8f0fa5512be5dc8a3f1)
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/8262)
Diffstat (limited to 'CHANGES')
| -rw-r--r-- | CHANGES | 6 |
1 files changed, 6 insertions, 0 deletions
@@ -9,6 +9,12 @@ Changes between 1.1.1a and 1.1.1b [xx XXX xxxx] + *) Added SCA hardening for modular field inversion in EC_GROUP through + a new dedicated field_inv() pointer in EC_METHOD. + This also addresses a leakage affecting conversions from projective + to affine coordinates. + [Billy Bob Brumley, Nicola Tuveri] + *) Change the info callback signals for the start and end of a post-handshake message exchange in TLSv1.3. In 1.1.1/1.1.1a we used SSL_CB_HANDSHAKE_START and SSL_CB_HANDSHAKE_DONE. Experience has shown that many applications get |