add --stop-after option

README.md

@@ -13,8 +13,9 @@ cargo install fingerprunk
 
 ## Usage
 
-Let's say you want to find keys whose fingerprints begin with `C0FFEE` and store them `secret.asc`.
-The regex for this is `^C0FFEE`. Now, simply use the following command to start the search:
+Let's say you want to find keys whose fingerprints begin with `C0FFEE` and store them
+at `secret.asc`. The regex for this is `^C0FFEE`. Now, simply use the following command to start
+the search:
 
 ```sh
 fingerprunk -r '^C0FFEE' >> secret.asc
@@ -49,25 +50,25 @@ Also see <https://en.wikipedia.org/wiki/Hexspeak> for some further examples of "
 
 ### How long does it take?
 
-On my machine with an AMD Ryzen 7 5800X Processor, Fingerprunk is able to generate and check about
-43300 keys per second. This means that for finding a fingerprint with a string of *n* specific
+On my machine with an AMD Ryzen 7 5800X processor, Fingerprunk is able to generate and check about
+41000 keys per second. This means that for finding a fingerprint with a string of *n* specific
 hexadecimal digits at a specific place, I could expect the following runtimes until finding the
 first key:
 
-| *n* |  expected tries | expected time |
-| --: | --------------: | ------------: |
-| *n* |             16ⁿ |  43300s / 16ⁿ |
-|   2 |             256 |   0.0059 secs |
-|   3 |            4096 |   0.0946 secs |
-|   4 |           65536 |      1.5 secs |
-|   5 |         1028576 |       24 secs |
-|   6 |        16777216 |      6.5 mins |
-|   7 |       268435456 |      103 mins |
-|   8 |      4294967296 |      27 hours |
-|   9 |     68719476736 |       18 days |
-|  10 |   1099511627776 |      293 days |
-|  11 |  17592186044416 |      13 years |
-|  12 | 281474976710656 |     206 years |
+| *n* |         estimate tries | estimate time |
+| --: | ---------------------: | ------------: |
+|   1 |              16 =  16¹ |    < 0.1 secs |
+|   2 |             256 =  16² |    < 0.1 secs |
+|   3 |            4096 =  16³ |      0.1 secs |
+|   4 |           65536 =  16⁴ |      1.6 secs |
+|   5 |         1048576 =  16⁵ |       26 secs |
+|   6 |        16777216 =  16⁶ |        7 mins |
+|   7 |       268435456 =  16⁷ |       2 hours |
+|   8 |      4294967296 =  16⁸ |        1 days |
+|   9 |     68719476736 =  16⁹ |       19 days |
+|  10 |   1099511627776 = 16¹⁰ |      310 days |
+|  11 |  17592186044416 = 16¹¹ |      14 years |
+|  12 | 281474976710656 = 16¹² |     218 years |
 
-As you can see, anything above 8 or 9 fixed digits is pretty much unfeasible, at least with
-a normal personal computer.
+As you can see, anything above 10 fixed digits is pretty much unfeasible, at least with a normal
+personal computer.

src/lib.rs

@@ -2,10 +2,11 @@
 
 use std::{
     fmt::{self, Write},
-    io::{self},
+    io,
+    num::NonZeroU64,
     sync::{
-        atomic::{AtomicU64, Ordering},
-        mpsc::{self, Receiver},
+        atomic::{AtomicBool, AtomicU64, Ordering},
+        mpsc,
     },
     thread,
     time::{Duration, Instant},
@@ -14,7 +15,7 @@ use std::{
 use fancy_regex::Regex;
 use num_integer::Integer;
 use sequoia_openpgp::{
-    Cert, Packet,
+    Cert, Packet, armor,
     crypto::Password,
     packet::{
         Key,
@@ -22,7 +23,7 @@ use sequoia_openpgp::{
         prelude::SignatureBuilder,
     },
     serialize::Serialize,
-    types::{HashAlgorithm, SignatureType, SymmetricAlgorithm},
+    types::{Curve, HashAlgorithm, SignatureType, SymmetricAlgorithm},
 };
 
 type SecretKey = Key<SecretParts, PrimaryRole>;
@@ -31,12 +32,15 @@ type SecretKey = Key<SecretParts, PrimaryRole>;
 pub struct Config {
     pub regex: Regex,
     pub status_enabled: bool,
+    pub stop_after: Option<NonZeroU64>,
     pub password: Option<Password>,
 }
 
 #[derive(Debug)]
 pub struct Fingerprunk {
     config: Config,
+    started_instant: Instant,
+    stop: AtomicBool,
     counter_tried: AtomicU64,
     counter_found: AtomicU64,
 }
@@ -52,12 +56,16 @@ impl Fingerprunk {
     pub fn new_from_config(config: Config) -> Self {
         Self {
             config,
+            started_instant: Instant::now(),
+            stop: AtomicBool::new(false),
             counter_tried: AtomicU64::new(0),
             counter_found: AtomicU64::new(0),
         }
     }
 
-    pub fn run(self) {
+    pub fn run(mut self) {
+        self.started_instant = Instant::now();
+
         let (tx, rx) = mpsc::channel();
 
         thread::scope(|scope| {
@@ -65,12 +73,16 @@ impl Fingerprunk {
 
             let ref_self = &self;
 
-            if self.config.status_enabled {
-                thread::Builder::new()
-                    .name("status_displayer".to_string())
-                    .spawn_scoped(scope, move || ref_self.status_displayer_thread())
-                    .expect(THREAD_SPAWN_EXPECT_MSG);
-            }
+            let status_displayer = if self.config.status_enabled {
+                Some(
+                    thread::Builder::new()
+                        .name("status_displayer".to_string())
+                        .spawn_scoped(scope, move || ref_self.status_displayer_thread())
+                        .expect(THREAD_SPAWN_EXPECT_MSG),
+                )
+            } else {
+                None
+            };
 
             for num in 0..num_cpus::get() {
                 let tx = tx.clone();
@@ -81,9 +93,19 @@ impl Fingerprunk {
                     .expect(THREAD_SPAWN_EXPECT_MSG);
             }
 
+            let on_stop = || {
+                // Ask all other threads to stop
+                self.stop.store(true, Ordering::Relaxed);
+
+                // Unpark the status displayer thread
+                if let Some(status_displayer) = status_displayer {
+                    status_displayer.thread().unpark();
+                }
+            };
+
             thread::Builder::new()
                 .name("finalizer".to_string())
-                .spawn_scoped(scope, move || ref_self.finalizer_thread(rx))
+                .spawn_scoped(scope, move || ref_self.finalizer_thread(rx, on_stop))
                 .expect(THREAD_SPAWN_EXPECT_MSG);
         });
     }
@@ -91,8 +113,9 @@ impl Fingerprunk {
     fn worker_thread(&self, matches_tx: mpsc::Sender<SecretKey>) {
         let mut fingerprint_hex = String::with_capacity(20 * 2);
 
-        loop {
-            let key = Key4::generate_ed25519().expect("should be able to generate key");
+        while !self.stop.load(Ordering::Relaxed) {
+            let key =
+                Key4::generate_ecc(true, Curve::Ed25519).expect("should be able to generate key");
             fingerprint_hex.clear();
             write!(fingerprint_hex, "{:X}", key.fingerprint())
                 .expect("should write into string without error");
@@ -113,20 +136,25 @@ impl Fingerprunk {
             .expect("should check regex without error")
     }
 
-    fn finalizer_thread(&self, matches_rx: Receiver<SecretKey>) {
+    fn finalizer_thread(&self, matches_rx: mpsc::Receiver<SecretKey>, on_stop: impl FnOnce()) {
         let mut stdout = io::stdout().lock();
 
         for key in matches_rx {
-            let result = self
+            let cert = self
                 .key_to_cert(&key)
-                .and_then(|cert| cert.as_tsk().armored().serialize(&mut stdout));
+                .expect("should be able to create certificate");
 
-            if let Err(err) = result {
-                eprintln!("Error: {err}");
-            } else {
-                self.counter_found.fetch_add(1, Ordering::Relaxed);
+            self.serialize_cert(cert, &mut stdout)
+                .expect("should be able to serialize certificate");
+
+            let prev = self.counter_found.fetch_add(1, Ordering::Relaxed);
+
+            if self.config.stop_after.is_some_and(|s| prev + 1 == s.get()) {
+                break;
             }
         }
+
+        on_stop();
     }
 
     fn key_to_cert(&self, key: &SecretKey) -> anyhow::Result<Cert> {
@@ -157,7 +185,45 @@ impl Fingerprunk {
         Cert::try_from(vec![secret_key_packet, Packet::from(sig)])
     }
 
+    fn serialize_cert(&self, cert: Cert, to: impl io::Write) -> anyhow::Result<()> {
+        let mut comments = cert.armor_headers();
+        comments.push(format!(
+            "Generated with Fingerprunk. Regex: {}",
+            self.config.regex
+        ));
+
+        let headers: Vec<_> = comments
+            .into_iter()
+            .map(|s| ("Comment".to_string(), s))
+            .collect();
+
+        let mut writer = armor::Writer::with_headers(to, armor::Kind::SecretKey, headers)?;
+
+        // Set the profile to RFC4880 because we generate v4 keys.
+        writer.set_profile(sequoia_openpgp::Profile::RFC4880)?;
+
+        cert.serialize(&mut writer)?;
+        writer.finalize()?;
+
+        Ok(())
+    }
+
     fn status_displayer_thread(&self) {
+        const UPDATE_INTERVAL: Duration = Duration::from_millis(250);
+
+        eprint!("\n\n\n\n\n");
+
+        while !self.stop.load(Ordering::Relaxed) {
+            self.print_status();
+            // We are parking the thread instead of sleeping so we can unpark it when we want to
+            // stop the program.
+            thread::park_timeout(UPDATE_INTERVAL);
+        }
+
+        self.print_status();
+    }
+
+    fn print_status(&self) {
         struct DurationDhms(Duration);
 
         impl fmt::Display for DurationDhms {
@@ -171,28 +237,20 @@ impl Fingerprunk {
             }
         }
 
-        const UPDATE_INTERVAL: Duration = Duration::from_millis(250);
         const FORMAT_WIDTH: usize = 12;
 
-        let start = Instant::now();
-
-        eprint!("\n\n\n\n\n");
-
-        loop {
-            let duration = DurationDhms(start.elapsed());
-            let keys = self.counter_tried.load(Ordering::Relaxed);
-            let keys_per_sec = keys as f64 / duration.0.as_secs_f64();
-            let found = self.counter_found.load(Ordering::Relaxed);
-            eprint!(
-                "\x1b[F\x1b[F\x1b[F\x1b[F\x1b[F\
+        let duration = DurationDhms(self.started_instant.elapsed());
+        let keys = self.counter_tried.load(Ordering::Relaxed);
+        let keys_per_sec = keys as f64 / duration.0.as_secs_f64();
+        let found = self.counter_found.load(Ordering::Relaxed);
+        eprint!(
+            "\x1b[F\x1b[F\x1b[F\x1b[F\x1b[F\
                 Time:  {duration}\n\
                 Tried: {keys: >w$} keys\n\
                 Rate:  {keys_per_sec: >w$.0} keys/s\n\
                 ---\n\
                 Found: {found: >w$} keys\n",
-                w = FORMAT_WIDTH
-            );
-            thread::sleep(UPDATE_INTERVAL);
-        }
+            w = FORMAT_WIDTH
+        );
     }
 }

src/main.rs

@@ -1,4 +1,7 @@
-use std::io::{self, IsTerminal};
+use std::{
+    io::{self, IsTerminal},
+    num::NonZeroU64,
+};
 
 use anyhow::{Context as AnyhowContext, anyhow};
 use clap::{ArgAction, Parser, ValueEnum};
@@ -26,6 +29,10 @@ struct Args {
     #[arg(long, value_enum, default_value_t)]
     status: StatusEnabled,
 
+    /// Stop once the specified number of matching keys has been found.
+    #[arg(long)]
+    stop_after: Option<NonZeroU64>,
+
     /// Prompt for a password and use it to encrypt found keys.
     ///
     /// By default, found keys are printed to stdout unencrypted. Use this if you actually plan to
@@ -78,6 +85,7 @@ fn main() -> anyhow::Result<()> {
     let config = fingerprunk::Config {
         regex: args.regex,
         status_enabled: args.status.evaluate(),
+        stop_after: args.stop_after,
         password,
     };