crypto: ecdh - add public key verification test

According to SP800-56A section 5.6.2.1, the public key to be processed
for the ECDH operation shall be checked for appropriateness. When the
public key is considered to be an ephemeral key, the partial validation
test as defined in SP800-56A section 5.6.2.3.4 can be applied.

The partial verification test requires the presence of the field
elements of a and b. For the implemented NIST curves, b is defined in
FIPS 186-4 appendix D.1.2. The element a is implicitly given with the
Weierstrass equation given in D.1.2 where a = p - 3.

Without the test, the NIST ACVP testing fails. After adding this check,
the NIST ACVP testing passes.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/ecc_curve_defs.h b/crypto/ecc_curve_defs.h
index b80f45d..94e883a 100644
--- a/crypto/ecc_curve_defs.h
+++ b/crypto/ecc_curve_defs.h
@@ -13,9 +13,11 @@
 	struct ecc_point g;
 	u64 *p;
 	u64 *n;
+	u64 *a;
+	u64 *b;
 };
 
-/* NIST P-192 */
+/* NIST P-192: a = p - 3 */
 static u64 nist_p192_g_x[] = { 0xF4FF0AFD82FF1012ull, 0x7CBF20EB43A18800ull,
 				0x188DA80EB03090F6ull };
 static u64 nist_p192_g_y[] = { 0x73F977A11E794811ull, 0x631011ED6B24CDD5ull,
@@ -24,6 +26,10 @@
 				0xFFFFFFFFFFFFFFFFull };
 static u64 nist_p192_n[] = { 0x146BC9B1B4D22831ull, 0xFFFFFFFF99DEF836ull,
 				0xFFFFFFFFFFFFFFFFull };
+static u64 nist_p192_a[] = { 0xFFFFFFFFFFFFFFFCull, 0xFFFFFFFFFFFFFFFEull,
+				0xFFFFFFFFFFFFFFFEull };
+static u64 nist_p192_b[] = { 0xFEB8DEECC146B9B1ull, 0x0FA7E9AB72243049ull,
+				0x64210519E59C80E7ull };
 static struct ecc_curve nist_p192 = {
 	.name = "nist_192",
 	.g = {
@@ -32,10 +38,12 @@
 		.ndigits = 3,
 	},
 	.p = nist_p192_p,
-	.n = nist_p192_n
+	.n = nist_p192_n,
+	.a = nist_p192_a,
+	.b = nist_p192_b
 };
 
-/* NIST P-256 */
+/* NIST P-256: a = p - 3 */
 static u64 nist_p256_g_x[] = { 0xF4A13945D898C296ull, 0x77037D812DEB33A0ull,
 				0xF8BCE6E563A440F2ull, 0x6B17D1F2E12C4247ull };
 static u64 nist_p256_g_y[] = { 0xCBB6406837BF51F5ull, 0x2BCE33576B315ECEull,
@@ -44,6 +52,10 @@
 				0x0000000000000000ull, 0xFFFFFFFF00000001ull };
 static u64 nist_p256_n[] = { 0xF3B9CAC2FC632551ull, 0xBCE6FAADA7179E84ull,
 				0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFF00000000ull };
+static u64 nist_p256_a[] = { 0xFFFFFFFFFFFFFFFCull, 0x00000000FFFFFFFFull,
+				0x0000000000000000ull, 0xFFFFFFFF00000001ull };
+static u64 nist_p256_b[] = { 0x3BCE3C3E27D2604Bull, 0x651D06B0CC53B0F6ull,
+				0xB3EBBD55769886BCull, 0x5AC635D8AA3A93E7ull };
 static struct ecc_curve nist_p256 = {
 	.name = "nist_256",
 	.g = {
@@ -52,7 +64,9 @@
 		.ndigits = 4,
 	},
 	.p = nist_p256_p,
-	.n = nist_p256_n
+	.n = nist_p256_n,
+	.a = nist_p256_a,
+	.b = nist_p256_b
 };
 
 #endif