add `FromStr` implementation for key types

src/key.rs

@@ -17,9 +17,9 @@
 
 #[cfg(any(test, feature = "rand"))] use rand::Rng;
 
-use std::{fmt, mem};
+use std::{fmt, mem, str};
 
-use super::{Secp256k1};
+use super::{from_hex, Secp256k1};
 use super::Error::{self, InvalidPublicKey, InvalidSecretKey};
 use Signing;
 use Verification;
@@ -40,6 +40,17 @@ impl fmt::Display for SecretKey {
     }
 }
 
+impl str::FromStr for SecretKey {
+    type Err = Error;
+    fn from_str(s: &str) -> Result<SecretKey, Error> {
+        let mut res = [0; constants::SECRET_KEY_SIZE];
+        match from_hex(s, &mut res) {
+            Ok(constants::SECRET_KEY_SIZE) => Ok(SecretKey(res)),
+            _ => Err(Error::InvalidSecretKey)
+        }
+    }
+}
+
 /// The number 1 encoded as a secret key
 /// Deprecated; `static` is not what I want; use `ONE_KEY` instead
 pub static ONE: SecretKey = SecretKey([0, 0, 0, 0, 0, 0, 0, 0,
@@ -73,6 +84,26 @@ impl fmt::Display for PublicKey {
     }
 }
 
+impl str::FromStr for PublicKey {
+    type Err = Error;
+    fn from_str(s: &str) -> Result<PublicKey, Error> {
+        let secp = Secp256k1::without_caps();
+        let mut res = [0; constants::UNCOMPRESSED_PUBLIC_KEY_SIZE];
+        match from_hex(s, &mut res) {
+            Ok(constants::PUBLIC_KEY_SIZE) => {
+                PublicKey::from_slice(
+                    &secp,
+                    &res[0..constants::PUBLIC_KEY_SIZE]
+                )
+            }
+            Ok(constants::UNCOMPRESSED_PUBLIC_KEY_SIZE) => {
+                PublicKey::from_slice(&secp, &res)
+            }
+            _ => Err(Error::InvalidPublicKey)
+        }
+    }
+}
+
 #[cfg(any(test, feature = "rand"))]
 fn random_32_bytes<R: Rng>(rng: &mut R) -> [u8; 32] {
     let mut ret = [0u8; 32];
@@ -318,34 +349,22 @@ impl<'de> ::serde::Deserialize<'de> for PublicKey {
 
 #[cfg(test)]
 mod test {
-    use super::super::{Secp256k1};
+    use Secp256k1;
+    use from_hex;
     use super::super::Error::{InvalidPublicKey, InvalidSecretKey};
     use super::{PublicKey, SecretKey};
     use super::super::constants;
 
     use rand::{Rng, thread_rng};
+    use std::iter;
+    use std::str::FromStr;
 
     macro_rules! hex {
-        ($hex:expr) => {
-            {
-                let mut vec = Vec::new();
-                let mut b = 0;
-                for (idx, c) in $hex.as_bytes().iter().enumerate() {
-                    b <<= 4;
-                    match *c {
-                        b'A'...b'F' => b |= c - b'A' + 10,
-                        b'a'...b'f' => b |= c - b'a' + 10,
-                        b'0'...b'9' => b |= c - b'0',
-                        _ => panic!("Bad hex"),
-                    }
-                    if (idx & 1) == 1 {
-                        vec.push(b);
-                        b = 0;
-                    }
-                }
-                vec
-            }
-        }
+        ($hex:expr) => ({
+            let mut result = vec![0; $hex.len() / 2];
+            from_hex($hex, &mut result).expect("valid hex string");
+            result
+        });
     }
 
     #[test]
@@ -482,10 +501,40 @@ mod test {
             sk.to_string(),
             "01010101010101010001020304050607ffff0000ffff00006363636363636363"
         );
+        assert_eq!(
+            SecretKey::from_str("01010101010101010001020304050607ffff0000ffff00006363636363636363").unwrap(),
+            sk
+        );
         assert_eq!(
             pk.to_string(),
             "0218845781f631c48f1c9709e23092067d06837f30aa0cd0544ac887fe91ddd166"
         );
+        assert_eq!(
+            PublicKey::from_str("0218845781f631c48f1c9709e23092067d06837f30aa0cd0544ac887fe91ddd166").unwrap(),
+            pk
+        );
+        assert_eq!(
+            PublicKey::from_str("04\
+                18845781f631c48f1c9709e23092067d06837f30aa0cd0544ac887fe91ddd166\
+                84B84DB303A340CD7D6823EE88174747D12A67D2F8F2F9BA40846EE5EE7A44F6"
+            ).unwrap(),
+            pk
+        );
+
+        assert!(SecretKey::from_str("fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").is_err());
+        assert!(SecretKey::from_str("01010101010101010001020304050607ffff0000ffff0000636363636363636363").is_err());
+        assert!(SecretKey::from_str("01010101010101010001020304050607ffff0000ffff0000636363636363636").is_err());
+        assert!(SecretKey::from_str("01010101010101010001020304050607ffff0000ffff000063636363636363").is_err());
+        assert!(SecretKey::from_str("01010101010101010001020304050607ffff0000ffff000063636363636363xx").is_err());
+        assert!(PublicKey::from_str("0300000000000000000000000000000000000000000000000000000000000000000").is_err());
+        assert!(PublicKey::from_str("0218845781f631c48f1c9709e23092067d06837f30aa0cd0544ac887fe91ddd16601").is_err());
+        assert!(PublicKey::from_str("0218845781f631c48f1c9709e23092067d06837f30aa0cd0544ac887fe91ddd16").is_err());
+        assert!(PublicKey::from_str("0218845781f631c48f1c9709e23092067d06837f30aa0cd0544ac887fe91ddd1").is_err());
+        assert!(PublicKey::from_str("xx0218845781f631c48f1c9709e23092067d06837f30aa0cd0544ac887fe91ddd1").is_err());
+
+        let long_str: String = iter::repeat('a').take(1024 * 1024).collect();
+        assert!(SecretKey::from_str(&long_str).is_err());
+        assert!(PublicKey::from_str(&long_str).is_err());
     }
 
     #[test]

src/lib.rs

@@ -708,36 +708,50 @@ impl<C: Verification> Secp256k1<C> {
     }
 }
 
+/// Utility function used to parse hex into a target u8 buffer. Returns
+/// the number of bytes converted or an error if it encounters an invalid
+/// character or unexpected end of string.
+fn from_hex(hex: &str, target: &mut [u8]) -> Result<usize, ()> {
+    if hex.len() % 2 == 1 || hex.len() > target.len() * 2 {
+        return Err(());
+    }
+
+    let mut b = 0;
+    let mut idx = 0;
+    for c in hex.bytes() {
+        b <<= 4;
+        match c {
+            b'A'...b'F' => b |= c - b'A' + 10,
+            b'a'...b'f' => b |= c - b'a' + 10,
+            b'0'...b'9' => b |= c - b'0',
+            _ => return Err(()),
+        }
+        if (idx & 1) == 1 {
+            target[idx / 2] = b;
+            b = 0;
+        }
+        idx += 1;
+    }
+    Ok(idx / 2)
+}
+
+
 #[cfg(test)]
 mod tests {
     use rand::{Rng, thread_rng};
 
     use key::{SecretKey, PublicKey};
+    use super::from_hex;
     use super::constants;
     use super::{Secp256k1, Signature, RecoverableSignature, Message, RecoveryId};
     use super::Error::{InvalidMessage, IncorrectSignature, InvalidSignature};
 
     macro_rules! hex {
-        ($hex:expr) => {
-            {
-                let mut vec = Vec::new();
-                let mut b = 0;
-                for (idx, c) in $hex.as_bytes().iter().enumerate() {
-                    b <<= 4;
-                    match *c {
-                        b'A'...b'F' => b |= c - b'A' + 10,
-                        b'a'...b'f' => b |= c - b'a' + 10,
-                        b'0'...b'9' => b |= c - b'0',
-                        _ => panic!("Bad hex"),
-                    }
-                    if (idx & 1) == 1 {
-                        vec.push(b);
-                        b = 0;
-                    }
-                }
-                vec
-            }
-        }
+        ($hex:expr) => ({
+            let mut result = vec![0; $hex.len() / 2];
+            from_hex($hex, &mut result).expect("valid hex string");
+            result
+        });
     }
 
     #[test]