converted errors from error_chain to failure

Cargo.toml

@@ -12,7 +12,7 @@ categories = ["cryptography"]
 
 [dependencies]
 byteorder = "1.2.3"
-error-chain = "0.12.0"
+failure = "0.1"
 init_with = "1.1.0"
 log = "0.4.1"
 pairing = { version = "0.14.2", features = ["u128-support"] }

src/error.rs

@@ -1,10 +1,13 @@
-error_chain! {
-    errors {
-        NotEnoughShares {
-            description("not enough signature shares")
-        }
-        DuplicateEntry {
-            description("signature shares contain a duplicated index")
-        }
-    }
-}
+//! Crypto errors.
+
+/// A crypto error.
+#[derive(Clone, Eq, PartialEq, Debug, Fail)]
+pub enum Error {
+    #[fail(display = "Not enough signature shares")]
+    NotEnoughShares,
+    #[fail(display = "Signature shares contain a duplicated index")]
+    DuplicateEntry,
+}
+
+/// A crypto result.
+pub type Result<T> = ::std::result::Result<T, Error>;

src/lib.rs

@@ -6,7 +6,7 @@
 extern crate bincode;
 extern crate byteorder;
 #[macro_use]
-extern crate error_chain;
+extern crate failure;
 extern crate init_with;
 #[macro_use]
 extern crate log;
@@ -39,7 +39,7 @@ use pairing::{CurveAffine, CurveProjective, Engine, Field};
 use rand::{ChaChaRng, OsRng, Rng, SeedableRng};
 use ring::digest;
 
-use error::{ErrorKind, Result};
+use error::{Error, Result};
 use into_fr::IntoFr;
 use poly::{Commitment, Poly};
 
@@ -499,13 +499,13 @@ where
         .map(|(i, sample)| (into_fr_plus_1(i), sample))
         .collect();
     if samples.len() < t {
-        return Err(ErrorKind::NotEnoughShares.into());
+        return Err(Error::NotEnoughShares);
     }
     let mut result = C::zero();
     let mut indexes = Vec::new();
     for (x, sample) in samples.iter().take(t) {
         if indexes.contains(x) {
-            return Err(ErrorKind::DuplicateEntry.into());
+            return Err(Error::DuplicateEntry);
         }
         indexes.push(x.clone());
         // Compute the value at 0 of the Lagrange polynomial that is `0` at the other data