openssl: Remove deprecated functions from des_encrypt()

NetworkManager-CI detected systematic failures on test scenarios using
MSCHAPv2 when wpa_supplicant uses OpenSSL-3.0.0.
The 'test_module_tests.py' script also fails, and the following log is
shown:

 1627404013.761569: generate_nt_response failed
 1627404013.761582: ms_funcs: 1 error

It seems that either DES_set_key() or DES_ecb_encrypt() changed their
semantic, but it doesn't make sense to fix them since their use has been
deprecated. Converting des_encrypt() to avoid use of deprecated
functions proved to fix the problem, and removed a couple of build
warnings at the same time.

Reported-by: Vladimir Benes <vbenes@redhat.com>
Signed-off-by: Davide Caratti <davide.caratti@gmail.com>

src/crypto/crypto_openssl.c

@@ -206,8 +206,8 @@ int md4_vector(size_t num_elem, const u8 *addr[], const size_t *len, u8 *mac)
 int des_encrypt(const u8 *clear, const u8 *key, u8 *cypher)
 {
 	u8 pkey[8], next, tmp;
-	int i;
-	DES_key_schedule ks;
+	int i, plen, ret = -1;
+	EVP_CIPHER_CTX *ctx;
 
 	/* Add parity bits to the key */
 	next = 0;
@@ -218,10 +218,19 @@ int des_encrypt(const u8 *clear, const u8 *key, u8 *cypher)
 	}
 	pkey[i] = next | 1;
 
-	DES_set_key((DES_cblock *) &pkey, &ks);
-	DES_ecb_encrypt((DES_cblock *) clear, (DES_cblock *) cypher, &ks,
-			DES_ENCRYPT);
-	return 0;
+	ctx = EVP_CIPHER_CTX_new();
+	if (ctx &&
+	    EVP_EncryptInit_ex(ctx, EVP_des_ecb(), NULL, pkey, NULL) == 1 &&
+	    EVP_CIPHER_CTX_set_padding(ctx, 0) == 1 &&
+	    EVP_EncryptUpdate(ctx, cypher, &plen, clear, 8) == 1 &&
+	    EVP_EncryptFinal_ex(ctx, &cypher[plen], &plen) == 1)
+		ret = 0;
+	else
+		wpa_printf(MSG_ERROR, "OpenSSL: DES encrypt failed");
+
+	if (ctx)
+		EVP_CIPHER_CTX_free(ctx);
+	return ret;
 }