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authorVitaly Chikunov <vt@altlinux.org>2018-11-05 11:36:18 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2018-11-16 14:09:39 +0800
commit2eb4942b6609d35a4e835644a33203b0aef7443d (patch)
treef591a91748069d4db65aadc43858ba3651478647 /crypto/ecc.c
parent196ad6043e9fe93c4ae3dac02b5c8fd337f58c2d (diff)
crypto: ecc - check for invalid values in the key verification test
Currently used scalar multiplication algorithm (Matthieu Rivain, 2011) have invalid values for scalar == 1, n-1, and for regularized version n-2, which was previously not checked. Verify that they are not used as private keys. Signed-off-by: Vitaly Chikunov <vt@altlinux.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/ecc.c')
-rw-r--r--crypto/ecc.c42
1 files changed, 26 insertions, 16 deletions
diff --git a/crypto/ecc.c b/crypto/ecc.c
index 8facafd67802..9d24e6522730 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -904,30 +904,43 @@ static inline void ecc_swap_digits(const u64 *in, u64 *out,
out[i] = __swab64(in[ndigits - 1 - i]);
}
-int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
- const u64 *private_key, unsigned int private_key_len)
+static int __ecc_is_key_valid(const struct ecc_curve *curve,
+ const u64 *private_key, unsigned int ndigits)
{
- int nbytes;
- const struct ecc_curve *curve = ecc_get_curve(curve_id);
+ u64 one[ECC_MAX_DIGITS] = { 1, };
+ u64 res[ECC_MAX_DIGITS];
if (!private_key)
return -EINVAL;
- nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
-
- if (private_key_len != nbytes)
+ if (curve->g.ndigits != ndigits)
return -EINVAL;
- if (vli_is_zero(private_key, ndigits))
+ /* Make sure the private key is in the range [2, n-3]. */
+ if (vli_cmp(one, private_key, ndigits) != -1)
return -EINVAL;
-
- /* Make sure the private key is in the range [1, n-1]. */
- if (vli_cmp(curve->n, private_key, ndigits) != 1)
+ vli_sub(res, curve->n, one, ndigits);
+ vli_sub(res, res, one, ndigits);
+ if (vli_cmp(res, private_key, ndigits) != 1)
return -EINVAL;
return 0;
}
+int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
+ const u64 *private_key, unsigned int private_key_len)
+{
+ int nbytes;
+ const struct ecc_curve *curve = ecc_get_curve(curve_id);
+
+ nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
+
+ if (private_key_len != nbytes)
+ return -EINVAL;
+
+ return __ecc_is_key_valid(curve, private_key, ndigits);
+}
+
/*
* ECC private keys are generated using the method of extra random bits,
* equivalent to that described in FIPS 186-4, Appendix B.4.1.
@@ -971,11 +984,8 @@ int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
if (err)
return err;
- if (vli_is_zero(priv, ndigits))
- return -EINVAL;
-
- /* Make sure the private key is in the range [1, n-1]. */
- if (vli_cmp(curve->n, priv, ndigits) != 1)
+ /* Make sure the private key is in the valid range. */
+ if (__ecc_is_key_valid(curve, priv, ndigits))
return -EINVAL;
ecc_swap_digits(priv, privkey, ndigits);