🚧 wip: considering passphrase-protected keys

bare_minimum_crypto/cpp/bmc_test.cpp

@@ -19,9 +19,46 @@ using namespace std;
 using nlohmann::json;
 using namespace BareMinimumCrypto;
 
+string get_passphrase_from_user () {
+	// In prod this would NOT be hard-coded.
+	return "Correct Horse Battery Staple";
+}
+
 int happy_path () {
 	// We generate a root key and keep it somewhere safe
 	// (offline, hopefully)
+	
+	// Passphrases are mandatory for root keys, and BMC also generates
+	// a salt to maximize entropy.
+	const auto passphrase = get_passphrase_from_user ();
+	vector <uint8_t> seed;
+	seed.resize (crypto_sign_SEEDBYTES);
+	
+	vector <uint8_t> salt;
+	salt.resize (crypto_pwhash_SALTBYTES);
+	randombytes_buf (salt.data (), salt.size ());
+	
+	if (crypto_pwhash (
+		seed.data (), seed.size (), 
+		passphrase.data (), passphrase.size (), 
+		salt.data (),
+		crypto_pwhash_OPSLIMIT_INTERACTIVE, crypto_pwhash_MEMLIMIT_INTERACTIVE,
+		crypto_pwhash_ALG_DEFAULT
+	) != 0) {
+		return 1;
+	}
+	
+	vector <uint8_t> pk;
+	pk.resize (crypto_sign_PUBLICKEYBYTES);
+	vector <uint8_t> sk;
+	sk.resize (crypto_sign_SECRETKEYBYTES);
+	
+	if (crypto_sign_seed_keypair (pk.data (), sk.data (), seed.data ()) != 0) {
+		return 1;
+	}
+	
+	cerr << "Passphrased root pub key " << base64_encode (pk) << endl;
+	
 	SigningKey root_key;
 	cerr << "Root pub key " << base64_encode (root_key.pubkey ()) << endl;
 	

bare_minimum_crypto/cpp/signing_key.h

@@ -17,6 +17,8 @@ namespace BareMinimumCrypto {
 	public:
 		SigningKey ();
 		
+		//static optional <SigningKey> generate_to_file
+		
 		vector <uint8_t> pubkey () const;
 		vector <uint8_t> pub_to_msgpack () const;