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crypto: ecc - check for invalid values in the key verification test

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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>
This commit is contained in:
Виталий Чикунов 2018-11-05 11:36:18 +03:00 committed by Herbert Xu
parent 196ad6043e
commit 2eb4942b66
1 changed files with 26 additions and 16 deletions
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42
crypto/ecc.c
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@ -904,28 +904,41 @@ static inline void ecc_swap_digits(const u64 *in, u64 *out,
out[i] = __swab64(in[ndigits - 1 - i]);
}
static int __ecc_is_key_valid(const struct ecc_curve *curve,
const u64 *private_key, unsigned int ndigits)
{
u64 one[ECC_MAX_DIGITS] = { 1, };
u64 res[ECC_MAX_DIGITS];
if (!private_key)
return -EINVAL;
if (curve->g.ndigits != ndigits)
return -EINVAL;
/* Make sure the private key is in the range [2, n-3]. */
if (vli_cmp(one, private_key, ndigits) != -1)
return -EINVAL;
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);
if (!private_key)
return -EINVAL;
nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
if (private_key_len != nbytes)
return -EINVAL;
if (vli_is_zero(private_key, ndigits))
return -EINVAL;
/* Make sure the private key is in the range [1, n-1]. */
if (vli_cmp(curve->n, private_key, ndigits) != 1)
return -EINVAL;
return 0;
return __ecc_is_key_valid(curve, private_key, ndigits);
}
/*
@ -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);