Add support for generating ecc private keys. Generation of ecc private keys is helpful in a user-space to kernel ecdh offload because the keys are not revealed to user-space. Private key generation is also helpful to implement forward secrecy. Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx> --- crypto/ecc.c | 20 ++++++++++++++++++++ crypto/ecc.h | 14 ++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/crypto/ecc.c b/crypto/ecc.c index 414c78a..a591907 100644 --- a/crypto/ecc.c +++ b/crypto/ecc.c @@ -927,6 +927,26 @@ int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, return 0; } +int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey) +{ + const struct ecc_curve *curve = ecc_get_curve(curve_id); + u64 priv[ndigits]; + unsigned int nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT; + + get_random_bytes(priv, nbytes); + + 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) + return -EINVAL; + + ecc_swap_digits(priv, privkey, ndigits); + + return 0; +} + int ecdh_make_pub_key(unsigned int curve_id, unsigned int ndigits, const u8 *private_key, unsigned int private_key_len, u8 *public_key, unsigned int public_key_len) diff --git a/crypto/ecc.h b/crypto/ecc.h index 663d598..b94b7ce 100644 --- a/crypto/ecc.h +++ b/crypto/ecc.h @@ -44,6 +44,20 @@ int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, const u8 *private_key, unsigned int private_key_len); /** + * ecc_gen_privkey() - Generates an ECC private key. + * The private key is a random integer in the range 0 < random < n, where n is a + * prime that is the order of the cyclic subgroup generated by the distinguished + * point G. + * @curve_id: id representing the curve to use + * @ndigits: curve number of digits + * @private_key: buffer for storing the generated private key + * + * Returns 0 if the private key was generated successfully, a negative value + * if an error occurred. + */ +int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey); + +/** * ecdh_make_pub_key() - Compute an ECC public key * * @curve_id: id representing the curve to use -- 2.7.4