SKALE-2844 add docs

SEKManager.cpp

@@ -135,7 +135,8 @@ void gen_SEK(){
   sek_file.clear();
 
   cout << "ATTENTION! YOUR BACKUP KEY WILL BE WROTE INTO backup_key.txt.\n" <<
-          "PLEASE COPY IT TO THE SAFE PLACE AND THEN DELETE THE FILE MANUALLY" << endl;
+          "PLEASE COPY IT TO THE SAFE PLACE AND THEN DELETE THE FILE MANUALLY RUNNING FOLLOWING COMMAND:\n" <<
+          "`sudo apt-get install secure-delete && srm -vz backup_key.txt`" << endl;
   sek_file << SEK;
 
   if (!autoconfirm) {

docs/backup-procedure.md

@@ -4,6 +4,10 @@
 
 When SGXWallet is initialized, the server will print the backup key. 
 **This key must be securely recorded and stored.**
+The key will be stored in file "backup_key.txt". Remove it once you store it in a safe place with following command:
+```bash
+sudo apt-get install secure-delete && srm -vz backup_key.txt
+```
 
 Master-Slave replication is recommended to support the SGXWallet backup strategy. Below are general instructions for a basic backup and recovery process.
 

secure_enclave/DKGUtils.cpp

@@ -57,8 +57,7 @@ string stringFromFr(libff::alt_bn128_Fr& _el) {
     return string(tmp);
 }
 
-template<class T>
-string ConvertToString(T field_elem, int base = 10) {
+template<class T> string ConvertToString(T field_elem, int base = 10) {
   mpz_t t;
   mpz_init(t);