diff options
| author | Tomas Mraz <tomas@openssl.org> | 2022-06-06 10:22:00 +0200 |
|---|---|---|
| committer | Hugo Landau <hlandau@openssl.org> | 2022-07-18 08:06:17 +0100 |
| commit | ddb13b283be84d771deba1e964610b1670641f03 (patch) | |
| tree | bb021170034f9fcbafbbfd8e46a48b7884aa3d9d /crypto/ffc/ffc_key_generate.c | |
| parent | 358103b4a651ab3f392f088d86cd30469dccce2e (diff) | |
Use as small dh key size as possible to support the security
Longer private key sizes unnecessarily raise the cycles needed to
compute the shared secret without any increase of the real security.
We use minimum key sizes as defined in RFC7919.
For arbitrary parameters we cannot know whether they are safe
primes (we could test but that would be too inefficient) we have
to keep generating large keys.
However we now set a small dh->length when we are generating safe prime
parameters because we know it is safe to use small keys with them.
That means users need to regenerate the parameters if they
want to take the performance advantage of small private key.
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18480)
Diffstat (limited to 'crypto/ffc/ffc_key_generate.c')
| -rw-r--r-- | crypto/ffc/ffc_key_generate.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/crypto/ffc/ffc_key_generate.c b/crypto/ffc/ffc_key_generate.c index c18f349ee2..cb895f2abd 100644 --- a/crypto/ffc/ffc_key_generate.c +++ b/crypto/ffc/ffc_key_generate.c @@ -25,11 +25,11 @@ int ossl_ffc_generate_private_key(BN_CTX *ctx, const FFC_PARAMS *params, int ret = 0, qbits = BN_num_bits(params->q); BIGNUM *m, *two_powN = NULL; - /* Deal with the edge case where the value of N is not set */ - if (N == 0) - N = qbits; + /* Deal with the edge cases where the value of N and/or s is not set */ if (s == 0) - s = N / 2; + goto err; + if (N == 0) + N = params->keylength ? params->keylength : 2 * s; /* Step (2) : check range of N */ if (N < 2 * s || N > qbits) |