Part 1 of #1. Refactoring to separate lib from command line.

Cargo.lock

@@ -1,8 +1,9 @@
 [root]
-name = "secretshare"
-version = "0.1.6"
+name = "rusty-secrets"
+version = "0.0.1"
 dependencies = [
  "getopts 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.18 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

Cargo.toml

@@ -1,8 +1,7 @@
 [package]
-name = "secretshare"
-version = "0.1.6"
-authors = ["Sebastian Gesemann <s.gesemann@gmail.com>"]
-description = "This is an implementation of Shamir's secret sharing scheme."
+name = "rusty-secrets"
+version = "0.0.1"
+description = "Implementation of threshold Shamir secret sharing in the Rust programming language." 
 license = "GPLv3"
 readme = "README.md"
 
@@ -10,3 +9,12 @@ readme = "README.md"
 getopts = "^0.2.14"
 rustc-serialize = "^0.3.18"
 rand = "^0.3.14"
+libc = "^0.2.0"
+
+[lib]
+name = "rusty_secrets_lib"
+path = "src/lib/mod.rs"
+
+[[bin]]
+name = "rusty_secrets_bin"
+path = "src/main.rs"

README.md

@@ -1,4 +1,4 @@
-# secretshare
+# Rusty Secrets
 
 This program is an implementation of
 [Shamir's secret sharing](https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing).
@@ -107,3 +107,8 @@ field I used is the same as the one you can find in the RAID 6
 implementation of the Linux kernel or the Anubis block cipher:
 Gf(2^8) reduction polynomial is x^8 + x^4 + x^3 + x^2 + 1 or
 alternatively 11D in hex.
+
+## Credits
+
+Rusty Secrets was forked off [sellibitze's secretshare.](https://github.com/sellibitze/secretshare)
+

src/lib/custom_error.rs

@@ -0,0 +1,44 @@
+pub use std::convert;
+pub use std::io::prelude::*;
+
+use std::error;
+use std::fmt;
+use std::io;
+
+#[derive(Debug)]
+pub struct Error {
+    descr: &'static str,
+    detail: Option<String>,
+}
+
+impl Error {
+    pub fn new(descr: &'static str, detail: Option<String>) -> Error {
+        Error { descr: descr, detail: detail }
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.detail {
+            None => write!(f, "{}", self.descr),
+            Some(ref detail) => write!(f, "{} ({})", self.descr, detail)
+        }
+    }
+}
+
+impl error::Error for Error {
+    fn description(&self) -> &str { self.descr }
+    fn cause(&self) -> Option<&error::Error> { None }
+}
+
+impl convert::From<Error> for io::Error {
+    fn from(me: Error) -> io::Error {
+        io::Error::new(io::ErrorKind::Other, me)
+    }
+}
+
+pub fn other_io_err(descr: &'static str, detail: Option<String>) -> io::Error {
+    convert::From::from(
+        Error::new(descr, detail)
+    )
+}

src/lib/gf256.rs

@@ -140,4 +140,3 @@ impl Div<Gf256> for Gf256 {
 		}
 	}
 }
-

src/lib/mod.rs

@@ -0,0 +1,111 @@
+extern crate rustc_serialize as serialize;
+extern crate rand;
+
+use self::rand::{ Rng, OsRng };
+pub use self::serialize::base64::{ self, FromBase64, ToBase64 };
+
+mod gf256;
+use self::gf256::Gf256;
+
+use std::io;
+pub use std::str;
+use std::iter::repeat;
+
+pub mod custom_error;
+use self::custom_error::*;
+
+fn new_vec<T: Clone>(n: usize, x: T) -> Vec<T> {
+	repeat(x).take(n).collect()
+}
+
+/// evaluates a polynomial at x=1, 2, 3, ... n (inclusive)
+fn encode<W: Write>(src: &[u8], n: u8, w: &mut W) -> io::Result<()> {
+	for raw_x in 1 .. ((n as u16) + 1) {
+		let x = Gf256::from_byte(raw_x as u8);
+		let mut fac = Gf256::one();
+		let mut acc = Gf256::zero();
+		for &coeff in src.iter() {
+			acc = acc + fac * Gf256::from_byte(coeff);
+			fac = fac * x;
+		}
+		try!(w.write(&[acc.to_byte()]));
+	}
+	Ok(())
+}
+
+/// evaluates an interpolated polynomial at `raw_x` where
+/// the polynomial is determined using Lagrangian interpolation
+/// based on the given x/y coordinates `src`.
+fn lagrange_interpolate(src: &[(u8, u8)], raw_x: u8) -> u8 {
+	let x = Gf256::from_byte(raw_x);
+	let mut sum = Gf256::zero();
+	for (i, &(raw_xi, raw_yi)) in src.iter().enumerate() {
+		let xi = Gf256::from_byte(raw_xi);
+		let yi = Gf256::from_byte(raw_yi);
+		let mut lix = Gf256::one();
+		for (j, &(raw_xj, _)) in src.iter().enumerate() {
+			if i != j {
+				let xj = Gf256::from_byte(raw_xj);
+				let delta = xi - xj;
+				assert!(delta.poly !=0, "Duplicate shares");
+				lix = lix * (x - xj) / delta;
+			}
+		}
+		sum = sum + lix * yi;
+	}
+	sum.to_byte()
+}
+
+fn secret_share(src: &[u8], k: u8, n: u8) -> io::Result<Vec<Vec<u8>>> {
+	let mut result = Vec::with_capacity(n as usize);
+	for _ in 0 .. (n as usize) {
+		result.push(new_vec(src.len(), 0u8));
+	}
+	let mut col_in = new_vec(k as usize, 0u8);
+	let mut col_out = Vec::with_capacity(n as usize);
+	let mut osrng = try!(OsRng::new());
+	for (c, &s) in src.iter().enumerate() {
+		col_in[0] = s;
+		osrng.fill_bytes(&mut col_in[1..]);
+		col_out.clear();
+		try!(encode(&*col_in, n, &mut col_out));
+		for (&y, share) in col_out.iter().zip(result.iter_mut()) {
+			share[c] = y;
+		}
+	}
+	Ok(result)
+}
+
+pub fn perform_encode(k: u8, n: u8, secret: Vec<u8>) -> io::Result<Vec<Vec<u8>>> {
+	let shares = try!(secret_share(&*secret, k, n));
+	let config = base64::Config {
+		pad: false,
+		..base64::STANDARD
+	};
+
+	let mut result = Vec::with_capacity(n as usize);
+
+	for (index, share) in shares.iter().enumerate() {
+		let salad = share.to_base64(config);
+		let string = format!("{}-{}-{}", k, index+1, salad).into_bytes();
+		result.push(string);
+	}
+
+	Ok(result)
+}
+
+pub fn perform_decode(k: u8, shares: Vec<(u8,Vec<u8>)>) -> io::Result<Vec<u8>> {
+	assert!(!shares.is_empty());
+	let slen = shares[0].1.len();
+	let mut col_in = Vec::with_capacity(k as usize);
+	let mut secret = Vec::with_capacity(slen);
+	for byteindex in 0 .. slen {
+		col_in.clear();
+		for s in shares.iter().take(k as usize) {
+			col_in.push((s.0, s.1[byteindex]));
+		}
+		secret.push(lagrange_interpolate(&*col_in, 0u8));
+	}
+
+	return Ok(secret) as io::Result<Vec<u8>>;
+}

src/main.rs

@@ -1,58 +1,19 @@
-extern crate rustc_serialize as serialize;
 extern crate getopts;
-extern crate rand;
 
-use std::convert;
-use std::env;
-use std::error;
-use std::fmt;
+use getopts::Options;
+
+use std::str;
+use lib::custom_error::*;
+use lib::serialize::base64::{ FromBase64 };
+mod lib;
+
 use std::io;
-use std::io::prelude::*;
-use std::iter::repeat;
+use std::env;
 use std::num;
 
-use rand::{ Rng, OsRng };
-use getopts::Options;
-use serialize::base64::{ self, FromBase64, ToBase64 };
-
-use gf256::Gf256;
-
-mod gf256;
-
-fn new_vec<T: Clone>(n: usize, x: T) -> Vec<T> {
-	repeat(x).take(n).collect()
-}
-
-#[derive(Debug)]
-pub struct Error {
-    descr: &'static str,
-    detail: Option<String>,
-}
-
-impl Error {
-    fn new(descr: &'static str, detail: Option<String>) -> Error {
-        Error { descr: descr, detail: detail }
-    }
-}
-
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self.detail {
-            None => write!(f, "{}", self.descr),
-            Some(ref detail) => write!(f, "{} ({})", self.descr, detail)
-        }
-    }
-}
-
-impl error::Error for Error {
-    fn description(&self) -> &str { self.descr }
-    fn cause(&self) -> Option<&error::Error> { None }
-}
-
-impl convert::From<Error> for io::Error {
-    fn from(me: Error) -> io::Error {
-        io::Error::new(io::ErrorKind::Other, me)
-    }
+enum Action {
+	Encode(u8, u8), // k and n parameter
+	Decode
 }
 
 // a try!-like macro for Option<T> expressions that takes
@@ -67,94 +28,71 @@ macro_rules! otry {
 	)
 }
 
-/// maps a ParseIntError to an io::Error
-fn pie2io(p: num::ParseIntError) -> io::Error {
-    convert::From::from(
-        Error::new("Integer parsing error", Some(p.to_string()))
-    )
-}
+fn main() {
+	let mut stderr = io::stderr();
+	let args: Vec<String> = env::args().collect();
 
-fn other_io_err(descr: &'static str, detail: Option<String>) -> io::Error {
-    convert::From::from(
-        Error::new(descr, detail)
-    )
-}
-
-/// evaluates a polynomial at x=1, 2, 3, ... n (inclusive)
-fn encode<W: Write>(src: &[u8], n: u8, w: &mut W) -> io::Result<()> {
-	for raw_x in 1 .. ((n as u16) + 1) {
-		let x = Gf256::from_byte(raw_x as u8);
-		let mut fac = Gf256::one();
-		let mut acc = Gf256::zero();
-		for &coeff in src.iter() {
-			acc = acc + fac * Gf256::from_byte(coeff);
-			fac = fac * x;
+	let mut opts = Options::new();
+	opts.optflag("h", "help", "print this help text");
+	opts.optflag("d", "decode", "for decoding");
+	opts.optopt("e", "encode", "for encoding, K is the required number of \
+	                            shares for decoding, N is the number of shares \
+	                            to generate. 1 <= K <= N <= 255", "K,N");
+	let opt_matches = match opts.parse(&args[1..]) {
+		Ok(m) => m,
+		Err(f) => {
+			drop(writeln!(&mut stderr, "Error: {}", f));
+			// env::set_exit_status(1); // FIXME: unstable feature
+			return;
 		}
-		try!(w.write(&[acc.to_byte()]));
-	}
-	Ok(())
-}
+	};
 
-/// evaluates an interpolated polynomial at `raw_x` where
-/// the polynomial is determined using Lagrangian interpolation
-/// based on the given x/y coordinates `src`.
-fn lagrange_interpolate(src: &[(u8, u8)], raw_x: u8) -> u8 {
-	let x = Gf256::from_byte(raw_x);
-	let mut sum = Gf256::zero();
-	for (i, &(raw_xi, raw_yi)) in src.iter().enumerate() {
-		let xi = Gf256::from_byte(raw_xi);
-		let yi = Gf256::from_byte(raw_yi);
-		let mut lix = Gf256::one();
-		for (j, &(raw_xj, _)) in src.iter().enumerate() {
-			if i != j {
-				let xj = Gf256::from_byte(raw_xj);
-				let delta = xi - xj;
-				assert!(delta.poly !=0, "Duplicate shares");
-				lix = lix * (x - xj) / delta;
+	if args.len() < 2 || opt_matches.opt_present("h") {
+		println!(
+"The program secretshare is an implementation of Shamir's secret sharing scheme.\n\
+ It is applied byte-wise within a finite field for arbitrarily long secrets.\n");
+		println!("{}", opts.usage("Usage: rustysecrets [options]"));
+		println!("Input is read from STDIN and output is written to STDOUT.");
+ 		return;
+	}
+
+	let action: Result<_,_> =
+		match (opt_matches.opt_present("e"), opt_matches.opt_present("d")) {
+			(false, false) => Err("Nothing to do! Use -e or -d"),
+			(true, true) => Err("Use either -e or -d and not both"),
+			(false, true) => Ok(Action::Decode),
+			(true, false) => {
+				if let Some(param) = opt_matches.opt_str("e") {
+					if let Ok((k,n)) = parse_k_n(&*param) {
+						if 0 < k && k <= n {
+							Ok(Action::Encode(k,n))
+						} else {
+							Err("Invalid encoding parameters K,N")
+						}
+					} else {
+						Err("Could not parse K,N parameters")
+					}
+				} else {
+					Err("No parameter for -e or -d provided")
+				}
 			}
-		}
-		sum = sum + lix * yi;
+		};
+
+	let result =
+		match action {
+			Ok(Action::Encode(k,n)) => perform_encode_from_io(k, n),
+			Ok(Action::Decode) => perform_decode_from_io(),
+			Err(e) => Err(other_io_err(e, None))
+		};
+
+	if let Err(e) = result {
+		drop(writeln!(&mut stderr, "{}", e));
+		// env::set_exit_status(1); // FIXME: unstable feature
 	}
-	sum.to_byte()
 }
 
-fn secret_share(src: &[u8], k: u8, n: u8) -> io::Result<Vec<Vec<u8>>> {
-	let mut result = Vec::with_capacity(n as usize);
-	for _ in 0 .. (n as usize) {
-		result.push(new_vec(src.len(), 0u8));
-	}
-	let mut col_in = new_vec(k as usize, 0u8);
-	let mut col_out = Vec::with_capacity(n as usize);
-	let mut osrng = try!(OsRng::new());
-	for (c, &s) in src.iter().enumerate() {
-		col_in[0] = s;
-		osrng.fill_bytes(&mut col_in[1..]);
-		col_out.clear();
-		try!(encode(&*col_in, n, &mut col_out));
-		for (&y, share) in col_out.iter().zip(result.iter_mut()) {
-			share[c] = y;
-		}
-	}
-	Ok(result)
-}
-
-enum Action {
-	Encode(u8, u8), // k and n parameter
-	Decode
-}
-
-fn parse_k_n(s: &str) -> io::Result<(u8, u8)> {
-	let mut iter = s.split(',');
-	let msg = "K and N have to be separated with a comma";
-	let s1 = otry!(iter.next(), msg).trim();
-	let s2 = otry!(iter.next(), msg).trim();
-	let k = try!(s1.parse().map_err(pie2io));
-	let n = try!(s2.parse().map_err(pie2io));
-	Ok((k, n))
-}
-
-fn perform_encode(k: u8, n: u8) -> io::Result<()> {
-    let secret = {
+fn perform_encode_from_io(k: u8, n: u8) -> io::Result<()> {
+	let secret = {
         let limit: usize = 0x10000;
         let stdin = io::stdin();
         let mut locked = stdin.lock();
@@ -169,16 +107,14 @@ fn perform_encode(k: u8, n: u8) -> io::Result<()> {
         }
         tmp
     };
-	let shares = try!(secret_share(&*secret, k, n));
-	let config = base64::Config {
-		pad: false,
-		..base64::STANDARD
-	};
-	for (index, share) in shares.iter().enumerate() {
-		let salad = share.to_base64(config);
-		println!("{}-{}-{}", k, index+1, salad);
+	match lib::perform_encode(k, n, secret) {
+		Ok(shares) => {
+			for share in shares {println!("{:?}", str::from_utf8(&share).unwrap())};
+		}
+		Err(e) => { return Err(e) as io::Result<()>; }
 	}
-	Ok(())
+
+	return Ok(()) as io::Result<()>;
 }
 
 /// reads shares from stdin and returns Ok(k, shares) on success
@@ -195,7 +131,7 @@ fn read_shares() -> io::Result<(u8, Vec<(u8,Vec<u8>)>)> {
 		let parts: Vec<_> = line.trim().split('-').collect();
 		if parts.len() < 3 || parts.len() > 4 {
 			return Err(other_io_err("Share parse error: Expected 3 or 4 \
-			                         parts searated by a minus sign", None));
+			                         parts separated by a minus sign", None));
 		}
 		let (k, n, p3) = {
 			let mut iter = parts.into_iter();
@@ -229,83 +165,32 @@ fn read_shares() -> io::Result<(u8, Vec<(u8,Vec<u8>)>)> {
 	Err(other_io_err("Not enough shares provided!", None))
 }
 
-fn perform_decode() -> io::Result<()> {
+fn perform_decode_from_io() -> io::Result<()> {
 	let (k, shares) = try!(read_shares());
-	assert!(!shares.is_empty());
-	let slen = shares[0].1.len();
-	let mut col_in = Vec::with_capacity(k as usize);
-	let mut secret = Vec::with_capacity(slen);
-	for byteindex in 0 .. slen {
-		col_in.clear();
-		for s in shares.iter().take(k as usize) {
-			col_in.push((s.0, s.1[byteindex]));
-		}
-		secret.push(lagrange_interpolate(&*col_in, 0u8));
-	}
-	let mut out = io::stdout();
-	try!(out.write_all(&*secret));
-	out.flush()
-}
 
-fn main() {
-	let mut stderr = io::stderr();
-	let args: Vec<String> = env::args().collect();
-
-	let mut opts = Options::new();
-	opts.optflag("h", "help", "print this help text");
-	opts.optflag("d", "decode", "for decoding");
-	opts.optopt("e", "encode", "for encoding, K is the required number of \
-	                            shares for decoding, N is the number of shares \
-	                            to generate. 1 <= K <= N <= 255", "K,N");
-	let opt_matches = match opts.parse(&args[1..]) {
-		Ok(m) => m,
-		Err(f) => {
-			drop(writeln!(&mut stderr, "Error: {}", f));
-			// env::set_exit_status(1); // FIXME: unstable feature
-			return;
+	return match lib::perform_decode(k, shares) {
+		Ok(secret) => {
+			let mut out = io::stdout();
+			try!(out.write_all(&*secret));
+			out.flush()
 		}
+		Err(e) => {Err(e) as io::Result<()>}
 	};
-
-	if args.len() < 2 || opt_matches.opt_present("h") {
-		println!(
-"The program secretshare is an implementation of Shamir's secret sharing scheme.\n\
- It is applied byte-wise within a finite field for arbitrarily long secrets.\n");
-		println!("{}", opts.usage("Usage: secretshare [options]"));
-		println!("Input is read from STDIN and output is written to STDOUT.");
- 		return;
-	}
-
-	let action: Result<_,_> =
-		match (opt_matches.opt_present("e"), opt_matches.opt_present("d")) {
-			(false, false) => Err("Nothing to do! Use -e or -d"),
-			(true, true) => Err("Use either -e or -d and not both"),
-			(false, true) => Ok(Action::Decode),
-			(true, false) => {
-				if let Some(param) = opt_matches.opt_str("e") {
-					if let Ok((k,n)) = parse_k_n(&*param) {
-						if 0 < k && k <= n {
-							Ok(Action::Encode(k,n))
-						} else {
-							Err("Invalid encoding parameters K,N")
-						}
-					} else {
-						Err("Could not parse K,N parameters")
-					}
-				} else {
-					Err("No parameter for -e or -d provided")
-				}
-			}
-		};
-
-	let result =
-		match action {
-			Ok(Action::Encode(k,n)) => perform_encode(k, n),
-			Ok(Action::Decode) => perform_decode(),
-			Err(e) => Err(other_io_err(e, None))
-		};
-
-	if let Err(e) = result {
-		drop(writeln!(&mut stderr, "{}", e));
-		// env::set_exit_status(1); // FIXME: unstable feature
-	}
+}
+
+fn parse_k_n(s: &str) -> io::Result<(u8, u8)> {
+	let mut iter = s.split(',');
+	let msg = "K and N have to be separated with a comma";
+	let s1 = otry!(iter.next(), msg).trim();
+	let s2 = otry!(iter.next(), msg).trim();
+	let k = try!(s1.parse().map_err(pie2io));
+	let n = try!(s2.parse().map_err(pie2io));
+	Ok((k, n))
+}
+
+/// maps a ParseIntError to an io::Error
+fn pie2io(p: num::ParseIntError) -> io::Error {
+    convert::From::from(
+        Error::new("Integer parsing error", Some(p.to_string()))
+    )
 }