Add the number of bits a curve has to the ecc_curve definition. This field
only needs to be set for curves that don't fill up all bytes in their
digits, such as NIST P521 which has only 9 bits in the most significant
digit. This field will be used to determine the number of bytes a curve
requires for its key coordinates for example.
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
crypto/ecc_curve_defs.h | 1 +
include/crypto/ecc_curve.h | 3 +++
2 files changed, 4 insertions(+)
diff --git a/crypto/ecc_curve_defs.h b/crypto/ecc_curve_defs.h
index 93a47a5d460a..09a221657c31 100644
--- a/crypto/ecc_curve_defs.h
+++ b/crypto/ecc_curve_defs.h
@@ -119,6 +119,7 @@ static u64 nist_p521_b[] = { 0xef451fd46b503f00ull, 0x3573df883d2c34f1ull,
0x051ull };
static struct ecc_curve nist_p521 = {
.name = "nist_521",
+ .nbits = 521,
.g = {
.x = nist_p521_g_x,
.y = nist_p521_g_y,
diff --git a/include/crypto/ecc_curve.h b/include/crypto/ecc_curve.h
index 70964781eb68..337a44956926 100644
--- a/include/crypto/ecc_curve.h
+++ b/include/crypto/ecc_curve.h
@@ -23,6 +23,8 @@ struct ecc_point {
* struct ecc_curve - definition of elliptic curve
*
* @name: Short name of the curve.
+ * @nbits: Curves that do not use all bits in their ndigits must specify
+ * their number of bits here, otherwise can leave at 0.
* @g: Generator point of the curve.
* @p: Prime number, if Barrett's reduction is used for this curve
* pre-calculated value 'mu' is appended to the @p after ndigits.
@@ -34,6 +36,7 @@ struct ecc_point {
*/
struct ecc_curve {
char *name;
+ unsigned int nbits;
struct ecc_point g;
u64 *p;
u64 *n;
--
2.43.0
