From e50e30a7f8eafea0a1975c555a6fdcab35d8243a Mon Sep 17 00:00:00 2001
From: Michael Brown
Date: Fri, 5 Dec 2025 13:00:12 +0000
Subject: [crypto] Expose the base point as an explicit elliptic curve property

Add the generator base point as an explicit property of an elliptic
curve, and remove the ability to pass a NULL to elliptic_multiply() to
imply the use of the generator base point.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/crypto/ecdhe.c       | 2 +-
 src/crypto/weierstrass.c | 6 +-----
 src/crypto/x25519.c      | 7 ++-----
 3 files changed, 4 insertions(+), 11 deletions(-)

(limited to 'src/crypto')

diff --git a/src/crypto/ecdhe.c b/src/crypto/ecdhe.c
index 5481b02eb..592c8ca1a 100644
--- a/src/crypto/ecdhe.c
+++ b/src/crypto/ecdhe.c
@@ -55,7 +55,7 @@ int ecdhe_key ( struct elliptic_curve *curve, const void *partner,
 	}
 
 	/* Construct public key */
-	if ( ( rc = elliptic_multiply ( curve, NULL, private,
+	if ( ( rc = elliptic_multiply ( curve, curve->base, private,
 					public ) ) != 0 ) {
 		DBGC ( curve, "CURVE %s could not generate public key: %s\n",
 		       curve->name, strerror ( rc ) );
diff --git a/src/crypto/weierstrass.c b/src/crypto/weierstrass.c
index c149c7b21..4974e5252 100644
--- a/src/crypto/weierstrass.c
+++ b/src/crypto/weierstrass.c
@@ -762,7 +762,7 @@ static int weierstrass_verify_raw ( const struct weierstrass_curve *curve,
  * Multiply curve point by scalar
  *
  * @v curve		Weierstrass curve
- * @v base		Base point (or NULL to use generator)
+ * @v base		Base point
  * @v scalar		Scalar multiple
  * @v result		Result point to fill in
  * @ret rc		Return status code
@@ -806,10 +806,6 @@ int weierstrass_multiply ( struct weierstrass_curve *curve, const void *base,
 	if ( ! prime2->element[0] )
 		weierstrass_init ( curve );
 
-	/* Use generator if applicable */
-	if ( ! base )
-		base = curve->base;
-
 	/* Convert input to projective coordinates in Montgomery form */
 	DBGC ( curve, "WEIERSTRASS %s base (", curve->name );
 	for ( i = 0, offset = 0 ; i < WEIERSTRASS_AXES ; i++, offset += len ) {
diff --git a/src/crypto/x25519.c b/src/crypto/x25519.c
index 41bc5fc5e..00a791877 100644
--- a/src/crypto/x25519.c
+++ b/src/crypto/x25519.c
@@ -822,7 +822,7 @@ int x25519_key ( const struct x25519_value *base,
 /**
  * Multiply scalar by curve point
  *
- * @v base		Base point (or NULL to use generator)
+ * @v base		Base point
  * @v scalar		Scalar multiple
  * @v result		Result point to fill in
  * @ret rc		Return status code
@@ -830,10 +830,6 @@ int x25519_key ( const struct x25519_value *base,
 static int x25519_curve_multiply ( const void *base, const void *scalar,
 				   void *result ) {
 
-	/* Use base point if applicable */
-	if ( ! base )
-		base = &x25519_generator;
-
 	return x25519_key ( base, scalar, result );
 }
 
@@ -842,5 +838,6 @@ struct elliptic_curve x25519_curve = {
 	.name = "x25519",
 	.pointsize = sizeof ( struct x25519_value ),
 	.keysize = sizeof ( struct x25519_value ),
+	.base = x25519_generator.raw,
 	.multiply = x25519_curve_multiply,
 };
-- 
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