crypto: ecdh - Add ECDH software support

* Implement ECDH under kpp API
 * Provide ECC software support for curve P-192 and
   P-256.
 * Add kpp test for ECDH with data generated by OpenSSL

Signed-off-by: Salvatore Benedetto <salvatore.benedetto@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 162d2f9a..5baaa9d 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -118,6 +118,11 @@
 	help
 	  Generic implementation of the Diffie-Hellman algorithm.
 
+config CRYPTO_ECDH
+	tristate "ECDH algorithm"
+	select CRYTPO_KPP
+	help
+	  Generic implementation of the ECDH algorithm
 
 config CRYPTO_MANAGER
 	tristate "Cryptographic algorithm manager"