Use a simpler increment seed iterator. (#186)

* Use a simpler increment seed iterator.

* Use more secure seeding.

substrate/Cargo.lock

@@ -1851,6 +1851,7 @@ name = "subkey"
 version = "0.1.0"
 dependencies = [
  "ed25519 0.1.0",
+ "rand 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "substrate-primitives 0.1.0",
 ]
 

substrate/subkey/Cargo.toml

@@ -6,3 +6,4 @@ authors = ["Parity Technologies <admin@parity.io>"]
 [dependencies]
 ed25519 = { version = "*", path = "../substrate/ed25519" }
 substrate-primitives = { version = "*", path = "../substrate/primitives" }
+rand = "0.4"

substrate/subkey/src/main.rs

 extern crate ed25519;
 extern crate substrate_primitives;
+extern crate rand;
 
+use rand::{OsRng, Rng};
 use std::env::args;
 use ed25519::Pair;
 use substrate_primitives::hexdisplay::HexDisplay;
@@ -14,6 +16,16 @@ fn good_waypoint(done: u64) -> u64 {
 	}
 }
 
+fn next_seed(mut seed: [u8; 32]) -> [u8; 32] {
+	for i in 0..32 {
+		match seed[i] {
+			255 => { seed[i] = 0; }
+			_ => { seed[i] += 1; break; }
+		}
+	}
+	return seed;
+}
+
 fn main() {
 	if args().len() != 2 {
 		println!("Usage: subkey <search string>");
@@ -32,9 +44,14 @@ fn main() {
 	};
 	let top = 30 + (desired.len() * 32);
 	let mut best = 0;
-	let mut seed = Pair::generate().public().0;
+	let mut seed = [0u8; 32];
 	let mut done = 0;
 	loop {
+		// reset to a new random seed at beginning and regularly after for paranoia.
+		if done % 100000 == 0 {
+			OsRng::new().unwrap().fill_bytes(&mut seed[..]);
+		}
+
 		let p = Pair::from_seed(&seed);
 		let ss58 = p.public().to_ss58check();
 		let s = score(&ss58);
@@ -45,7 +62,7 @@ fn main() {
 				break;
 			}
 		}
-		seed = p.public().0;
+		seed = next_seed(seed);
 		done += 1;
 
 		if done % good_waypoint(done) == 0 {