added reproducability Rng

src/main.rs

@@ -1,5 +1,8 @@
 use rand::Rng;
 use rand::rngs::OsRng;
+use rand::SeedableRng;
+use rand::rngs::StdRng;
+
 use std::fs;
 use rand::prelude::SliceRandom;
 use bitflags::bitflags;
@@ -127,7 +130,7 @@ fn validate_passphrase(password: &str, policy: &PassphraseConfig) -> bool {
     (policy.capitalize || upper) &&
         (policy.symbol || symbol) &&
         (policy.number || number) &&
-        (lower)
+        (lower) // all passwords need lower chars
 }
 
 impl Default for PasswordConfig {
@@ -142,7 +145,7 @@ impl Default for PasswordConfig {
     }
 }
 
-fn random_ascii(rng: &mut OsRng, char_set: &[u8]) -> u8 {
+fn random_ascii(rng: &mut impl Rng, char_set: &[u8]) -> u8 {
     // NOT IDEAL FOR CRYPTO/password generation 
     // let range_max = 122; // 125 - 33
     // let n = rng.next_u32() % range_max; // slightly modulo biased
@@ -161,7 +164,7 @@ fn random_ascii(rng: &mut OsRng, char_set: &[u8]) -> u8 {
 // log2(possible_symbols^len) yields bits of entropy
 // so say len is 20 and we use all 80 chars:
 // that's log2(80^20) -> 126.4 bits of entropy per password
-fn generate_password(config: &PasswordConfig, rng: &mut OsRng) -> Result<String,String> {
+fn generate_password(config: &PasswordConfig, rng: &mut impl Rng) -> Result<String,String> {
     if config.len < 8 {
         return Err(String::from("Password length not long enough"));
     }
@@ -207,7 +210,7 @@ fn generate_password(config: &PasswordConfig, rng: &mut OsRng) -> Result<String,
 // log2(18) -> 4.1 bits for separator assuming seporator is one of our SYMBOLs
 // total 70.5 bits of entropy
 fn generate_passphrase(config: &PassphraseConfig,
-        word_list: &[&str], rng: &mut OsRng) -> Result<String,String> {
+        word_list: &[&str], rng: &mut impl Rng) -> Result<String,String> {
     if config.phrases < 2 {
         return Err("Phrase count too low".to_string());
     }
@@ -235,12 +238,10 @@ fn generate_passphrase(config: &PassphraseConfig,
     Ok(res)
 }
 
-fn random_word<'a>(word_list: &[&'a str], rng: &mut OsRng) -> &'a str {
+fn random_word<'a>(word_list: &[&'a str], rng: &mut impl Rng) -> &'a str {
     word_list[rng.gen_range(0..word_list.len())]
 }
 
-// Some questions:
-// todo: “What if I need reproducibility?”
 fn main() {
     // todo: not cross-platform
     // todo: abstract this a bit
@@ -256,7 +257,13 @@ fn main() {
     // doesn't require seeding because it is backed by CSPRNG, backed by OS
     // the OS maintains it's own entropy from mouse movement, hardware noise,etc
     // we pass it through the functions to avoid a potential syscall
-    let mut rng = OsRng;
+    let mut _rng = OsRng;
+
+    // when we are looking for Reproducability we can use the same seed value
+    // to create our Rng. Because both StdRng and OsRng implement Rng
+    // we make our methods slightly more generic and this works just fine
+    // comment out when we need random version!
+    let mut rng = StdRng::seed_from_u64(42);
 
     // todo: add actual tests
     // password with alphnumeric