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Commit 2eb4942b authored by Vitaly Chikunov's avatar Vitaly Chikunov Committed by Herbert Xu
Browse files

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: default avatarVitaly Chikunov <vt@altlinux.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 196ad604

crypto/ecc.c

+26 −16
Original line number Diff line number Diff line
@@ -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);