samples: nrf9160: modem_shell: update the US server root CA used for FOTA

Earlier US AWS S3 servers have been using a different root CA, but
now those are migrating to the same root CA as other regions. Removed
the Baltimore CyberTrust Root CA which is no longer needed, because
all regions now use the same Amazon Root CA.

Signed-off-by: Tommi Kangas <[email protected]>

Author: tokangas

samples/nrf9160/modem_shell/src/fota/cert/Baltimore-CyberTrust-Root

@@ -9,18 +9,11 @@
 
 #include <zephyr.h>
 #include <sys/reboot.h>
-#include <modem/modem_key_mgmt.h>
 #include <net/fota_download.h>
 
 #include "fota.h"
 #include "mosh_print.h"
 
-#define MOSH_FOTA_US_TLS_SECURITY_TAG 4242424
-
-static const char us_root_ca_cert[] = {
-#include "cert/Baltimore-CyberTrust-Root"
-};
-
 static void reboot_timer_handler(struct k_timer *dummy)
 {
 	sys_reboot(SYS_REBOOT_WARM);
@@ -65,54 +58,12 @@ static void fota_download_callback(const struct fota_download_evt *evt)
 	}
 }
 
-static bool fota_us_ca_cert_exists(void)
-{
-	int err;
-	bool exists;
-
-	err = modem_key_mgmt_exists(MOSH_FOTA_US_TLS_SECURITY_TAG,
-				    MODEM_KEY_MGMT_CRED_TYPE_CA_CHAIN,
-				    &exists);
-
-	if (!err && exists) {
-		return true;
-	} else {
-		return false;
-	}
-}
-
-static int fota_write_us_ca_cert(void)
-{
-	return modem_key_mgmt_write(MOSH_FOTA_US_TLS_SECURITY_TAG,
-				    MODEM_KEY_MGMT_CRED_TYPE_CA_CHAIN,
-				    us_root_ca_cert, sizeof(us_root_ca_cert));
-}
-
 int fota_init(void)
 {
-	int err;
-
-	if (!fota_us_ca_cert_exists()) {
-		err = fota_write_us_ca_cert();
-		if (err) {
-			printk("Failed to write US server root CA to modem, error %d\n",
-			       err);
-		}
-	}
-
 	return fota_download_init(&fota_download_callback);
 }
 
 int fota_start(const char *host, const char *file)
 {
-	int sec_tag;
-
-	if (strstr(host, "us") != 0) {
-		/* The US server uses a different root CA. */
-		sec_tag = MOSH_FOTA_US_TLS_SECURITY_TAG;
-	} else {
-		sec_tag = CONFIG_NRF_CLOUD_SEC_TAG;
-	}
-
-	return fota_download_start(host, file, sec_tag, 0, 0);
+	return fota_download_start(host, file, CONFIG_NRF_CLOUD_SEC_TAG, 0, 0);
 }