examples/dtls-sock: add public key verification

examples/dtls-sock/Makefile

@@ -20,6 +20,10 @@ USEPKG += tinydtls
 
 # Pull in sock APIs
 USEMODULE += sock_dtls
+# When using asymmetric cryptography, e.g. ecc,
+# this verifies the public key against a known set.
+# It does not affect symmetric crypto e.g. PSK.
+USEMODULE += sock_dtls_verify_public_key
 USEMODULE += sock_udp
 
 # extra utilities for endpoint printing

examples/dtls-sock/dtls-client.c

@@ -41,6 +41,7 @@
 #ifdef CONFIG_DTLS_ECC
 static const ecdsa_public_key_t other_pubkeys0[] = {
     { .x = ecdsa_pub_key0_x, .y = ecdsa_pub_key0_y },
+    { .x = ecdsa_pub_key1_x, .y = ecdsa_pub_key1_y },
 };
 
 static const credman_credential_t credential0 = {