Upgrade to secp256k1 0.21

Release 0.21 includes a module restructure which we can now make use of.
This simplifies some imports.

Author: thomaseizinger

Cargo.toml

@@ -30,7 +30,7 @@ use-serde = ["serde", "secp256k1/serde"]
 use-rand = ["rand", "secp256k1/rand"]
 
 [dependencies]
-secp256k1 = "0.20.0"
+secp256k1 = "0.21.0"
 secp256k1-zkp-sys = { version = "0.4.0", default-features = false, path = "./secp256k1-zkp-sys" }
 rand = { version = "0.6", default-features = false, optional = true }
 serde = { version = "1.0", default-features = false, optional = true }

src/lib.rs

@@ -65,8 +65,6 @@ use core::{fmt, str};
 
 pub use secp256k1::*;
 
-pub use key::{PublicKey, SecretKey};
-
 #[cfg(feature = "serde")]
 mod serde_util;
 mod zkp;

src/zkp/ecdsa_adaptor.rs

@@ -13,10 +13,12 @@ use ffi::{self, CPtr, ECDSA_ADAPTOR_SIGNATURE_LENGTH};
 use rand::thread_rng;
 #[cfg(any(test, feature = "rand"))]
 use rand::{CryptoRng, Rng};
-use {constants, PublicKey, Secp256k1, SecretKey};
+use secp256k1::ecdsa::Signature;
+use secp256k1::{PublicKey, SecretKey};
+use {constants, Secp256k1};
 use {from_hex, Error};
 use {Message, Signing};
-use {Signature, Verification};
+use Verification;
 
 /// Represents an adaptor signature and dleq proof.
 #[derive(Debug, PartialEq, Clone, Copy, Eq)]

src/zkp/rangeproof.rs

@@ -2,11 +2,12 @@ use ffi::RANGEPROOF_MAX_LENGTH;
 use from_hex;
 use std::ops::Range;
 use std::str;
+use secp256k1::SecretKey;
 use Error;
 use Generator;
 use PedersenCommitment;
 use Verification;
-use {ffi, Secp256k1, SecretKey, Signing, Tweak};
+use {ffi, Secp256k1, Signing, Tweak};
 
 /// Represents a range proof.
 ///

src/zkp/whitelist.rs

@@ -8,9 +8,10 @@ use std::{fmt, str};
 use core::ptr;
 
 use ffi::CPtr;
+use secp256k1::{PublicKey, SecretKey};
 #[cfg(feature = "std")]
 use from_hex;
-use {ffi, secp256k1, Error, PublicKey, Secp256k1, SecretKey, Signing, Verification};
+use {ffi, secp256k1, Error, Secp256k1, Signing, Verification};
 
 /// A whitelist ring signature.
 #[derive(Clone, PartialEq, Eq, Hash)]