fix: dependency to cryptography

setup.cfg

@@ -21,7 +21,7 @@ packages = find:
 package_dir =
     =src
 install_requires =
-    crypto
+    cryptography
 
 [options.extras_require]
 dev =

setup.py

@@ -19,7 +19,7 @@
     packages=setuptools.find_packages(where="src"),
     package_dir={"": "src"},
     python_requires=">=3.7",
-    install_requires=["crypto"],
+    install_requires=["cryptography"],
     extras_require={
         "dev": ["pytest", "pytest-cov", "pytest-mock"],
         "fastapi": ["fastapi"],

src/pyzantium/chain.py

@@ -1,23 +1,47 @@
 from ctypes import Union
-import hashlib
-from .storage import Storage
+from cryptography.hazmat.primitives import hashes
 from typing import Union
+from .block import Block
+from .storage import Storage
+
+__all__ = ["Chain"]
 
 
 class Chain:
-    def __init__(self, *, hash: str, storage: Storage) -> None:
-        self._hash = hashlib[hash] if type(hash) == str else hash
+    """
+    Central class to handle bolckchain machinary over ``Storage``
+
+    This class hides storage and provide a higher level of bolckchain operation
+    that eases other operations like mining and block validation.
+
+    :param hash: The hash algorithm used in this blokchain
+    :param storage: storage of this blockchain
+    """
+
+    def __init__(self, *, hash: hashes.HashAlgorithm, storage: Storage) -> None:
+        self._hash = hash
         self._storage = storage
         self._last_hash = storage[-1]
 
+    def new_block(self) -> Block:
+        """Generate an empty block with preset properties
+
+        :rtype: pyzantium.Block
+        """
+        block = Block()
+        # TODO: Generate a block and initialize it's preveiuse hash
+
     @property
     def storage(self):
+        """Storage of this chain"""
         return self._storage
 
     @property
     def hash(self):
+        """Hash algorithm of this blockchain"""
         return self._hash
 
     @property
     def last_block_hash(self):
+        """Hash of last block"""
         return self._last_hash