Add support for pass-phrase seed generation.

common.h

@@ -13,6 +13,14 @@
 // full onion address, WITHOUT newline
 #define ONION_LEN 62
 
+// How many times we loop before a reseed
+#define DETERMINISTIC_LOOP_COUNT 1<<24
+
+// Argon2 hashed passphrase stretching settings
+#define PWHASH_OPSLIMIT 256
+#define PWHASH_MEMLIMIT 64 * 1024 * 1024
+#define PWHASH_ALG 	crypto_pwhash_ALG_ARGON2ID13
+
 extern pthread_mutex_t fout_mutex;
 extern FILE *fout;