* [PATCH] ecc: Add helper for multiplying a scalar with a curve generator
@ 2023-11-06 19:06 Marcel Holtmann
2023-11-08 2:24 ` Denis Kenzior
0 siblings, 1 reply; 2+ messages in thread
From: Marcel Holtmann @ 2023-11-06 19:06 UTC (permalink / raw)
To: ell
The SPAKE2+ key exchange protocol requires the ability to multiply a
random number with the curve generator. Instead of exposing the curve
generator expose a helper function that provides the multiplication.
---
ell/ecc.c | 12 ++++++++++++
ell/ecc.h | 2 ++
ell/ell.sym | 1 +
3 files changed, 15 insertions(+)
diff --git a/ell/ecc.c b/ell/ecc.c
index 59bff7bd5af1..ff147b84ed74 100644
--- a/ell/ecc.c
+++ b/ell/ecc.c
@@ -940,6 +940,18 @@ LIB_EXPORT bool l_ecc_point_multiply(struct l_ecc_point *ret,
return true;
}
+LIB_EXPORT bool l_ecc_point_multiply_g(struct l_ecc_point *ret,
+ const struct l_ecc_scalar *scalar)
+{
+ if (unlikely(!ret || !scalar))
+ return false;
+
+ _ecc_point_mult(ret, &scalar->curve->g, scalar->c, NULL,
+ scalar->curve->p);
+
+ return true;
+}
+
LIB_EXPORT bool l_ecc_point_add(struct l_ecc_point *ret,
const struct l_ecc_point *a,
const struct l_ecc_point *b)
diff --git a/ell/ecc.h b/ell/ecc.h
index 2f6faa4e79cd..de116f018b44 100644
--- a/ell/ecc.h
+++ b/ell/ecc.h
@@ -83,6 +83,8 @@ bool l_ecc_scalar_add(struct l_ecc_scalar *ret, const struct l_ecc_scalar *a,
bool l_ecc_point_multiply(struct l_ecc_point *ret,
const struct l_ecc_scalar *scalar,
const struct l_ecc_point *point);
+bool l_ecc_point_multiply_g(struct l_ecc_point *ret,
+ const struct l_ecc_scalar *scalar);
bool l_ecc_point_add(struct l_ecc_point *ret, const struct l_ecc_point *a,
const struct l_ecc_point *b);
bool l_ecc_point_inverse(struct l_ecc_point *p);
diff --git a/ell/ell.sym b/ell/ell.sym
index c457a7620376..0f593e1fc402 100644
--- a/ell/ell.sym
+++ b/ell/ell.sym
@@ -593,6 +593,7 @@ global:
l_ecc_point_get_data;
l_ecc_point_inverse;
l_ecc_point_multiply;
+ l_ecc_point_multiply_g;
l_ecc_point_new;
l_ecc_point_from_sswu;
l_ecc_point_clone;
--
2.41.0
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2023-11-06 19:06 [PATCH] ecc: Add helper for multiplying a scalar with a curve generator Marcel Holtmann
2023-11-08 2:24 ` Denis Kenzior
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