Consolidate crypto functionality in ethcore-crypto. (#8432)

* Consolidate crypto functionality in `ethcore-crypto`.

- Move `ecdh`/`ecies` modules to `ethkey`.
- Refactor `ethcore-crypto` to use file per module.
- Replace `subtle` with `ethcore_crypto::is_equal`.
- Add `aes_gcm` module to `ethcore-crypto`.

* Rename `aes::{encrypt,decrypt,decrypt_cbc}` ...

... to `aes::{encrypt_128_ctr,decrypt_128_ctr,decrypt_128_cbc}`.

ethcore/crypto/src/aes.rs

@@ -0,0 +1,54 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+use error::SymmError;
+use rcrypto::blockmodes::{CtrMode, CbcDecryptor, PkcsPadding};
+use rcrypto::aessafe::{AesSafe128Encryptor, AesSafe128Decryptor};
+use rcrypto::symmetriccipher::{Encryptor, Decryptor};
+use rcrypto::buffer::{RefReadBuffer, RefWriteBuffer, WriteBuffer};
+
+/// Encrypt a message (CTR mode).
+///
+/// Key (`k`) length and initialisation vector (`iv`) length have to be 16 bytes each.
+/// An error is returned if the input lengths are invalid.
+pub fn encrypt_128_ctr(k: &[u8], iv: &[u8], plain: &[u8], dest: &mut [u8]) -> Result<(), SymmError> {
+	let mut encryptor = CtrMode::new(AesSafe128Encryptor::new(k), iv.to_vec());
+	encryptor.encrypt(&mut RefReadBuffer::new(plain), &mut RefWriteBuffer::new(dest), true)?;
+	Ok(())
+}
+
+/// Decrypt a message (CTR mode).
+///
+/// Key (`k`) length and initialisation vector (`iv`) length have to be 16 bytes each.
+/// An error is returned if the input lengths are invalid.
+pub fn decrypt_128_ctr(k: &[u8], iv: &[u8], encrypted: &[u8], dest: &mut [u8]) -> Result<(), SymmError> {
+	let mut encryptor = CtrMode::new(AesSafe128Encryptor::new(k), iv.to_vec());
+	encryptor.decrypt(&mut RefReadBuffer::new(encrypted), &mut RefWriteBuffer::new(dest), true)?;
+	Ok(())
+}
+
+/// Decrypt a message (CBC mode).
+///
+/// Key (`k`) length and initialisation vector (`iv`) length have to be 16 bytes each.
+/// An error is returned if the input lengths are invalid.
+pub fn decrypt_128_cbc(k: &[u8], iv: &[u8], encrypted: &[u8], dest: &mut [u8]) -> Result<usize, SymmError> {
+	let mut encryptor = CbcDecryptor::new(AesSafe128Decryptor::new(k), PkcsPadding, iv.to_vec());
+	let len = dest.len();
+	let mut buffer = RefWriteBuffer::new(dest);
+	encryptor.decrypt(&mut RefReadBuffer::new(encrypted), &mut buffer, true)?;
+	Ok(len - buffer.remaining())
+}
+