Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/hashlib.pyi

@@ -0,0 +1,124 @@
+import sys
+from _typeshed import ReadableBuffer
+from typing import AbstractSet, Optional
+
+class _Hash(object):
+    digest_size: int
+    block_size: int
+
+    # [Python documentation note] Changed in version 3.4: The name attribute has
+    # been present in CPython since its inception, but until Python 3.4 was not
+    # formally specified, so may not exist on some platforms
+    name: str
+    def __init__(self, data: ReadableBuffer = ...) -> None: ...
+    def copy(self) -> _Hash: ...
+    def digest(self) -> bytes: ...
+    def hexdigest(self) -> str: ...
+    def update(self, __data: ReadableBuffer) -> None: ...
+
+if sys.version_info >= (3, 9):
+    def new(name: str, data: ReadableBuffer = ..., *, usedforsecurity: bool = ...) -> _Hash: ...
+    def md5(string: ReadableBuffer = ..., *, usedforsecurity: bool = ...) -> _Hash: ...
+    def sha1(string: ReadableBuffer = ..., *, usedforsecurity: bool = ...) -> _Hash: ...
+    def sha224(string: ReadableBuffer = ..., *, usedforsecurity: bool = ...) -> _Hash: ...
+    def sha256(string: ReadableBuffer = ..., *, usedforsecurity: bool = ...) -> _Hash: ...
+    def sha384(string: ReadableBuffer = ..., *, usedforsecurity: bool = ...) -> _Hash: ...
+    def sha512(string: ReadableBuffer = ..., *, usedforsecurity: bool = ...) -> _Hash: ...
+
+elif sys.version_info >= (3, 8):
+    def new(name: str, data: ReadableBuffer = ...) -> _Hash: ...
+    def md5(string: ReadableBuffer = ...) -> _Hash: ...
+    def sha1(string: ReadableBuffer = ...) -> _Hash: ...
+    def sha224(string: ReadableBuffer = ...) -> _Hash: ...
+    def sha256(string: ReadableBuffer = ...) -> _Hash: ...
+    def sha384(string: ReadableBuffer = ...) -> _Hash: ...
+    def sha512(string: ReadableBuffer = ...) -> _Hash: ...
+
+else:
+    def new(name: str, data: ReadableBuffer = ...) -> _Hash: ...
+    def md5(__string: ReadableBuffer = ...) -> _Hash: ...
+    def sha1(__string: ReadableBuffer = ...) -> _Hash: ...
+    def sha224(__string: ReadableBuffer = ...) -> _Hash: ...
+    def sha256(__string: ReadableBuffer = ...) -> _Hash: ...
+    def sha384(__string: ReadableBuffer = ...) -> _Hash: ...
+    def sha512(__string: ReadableBuffer = ...) -> _Hash: ...
+
+algorithms_guaranteed: AbstractSet[str]
+algorithms_available: AbstractSet[str]
+
+def pbkdf2_hmac(
+    hash_name: str, password: ReadableBuffer, salt: ReadableBuffer, iterations: int, dklen: Optional[int] = ...
+) -> bytes: ...
+
+class _VarLenHash(object):
+    digest_size: int
+    block_size: int
+    name: str
+    def __init__(self, data: ReadableBuffer = ...) -> None: ...
+    def copy(self) -> _VarLenHash: ...
+    def digest(self, __length: int) -> bytes: ...
+    def hexdigest(self, __length: int) -> str: ...
+    def update(self, __data: ReadableBuffer) -> None: ...
+
+sha3_224 = _Hash
+sha3_256 = _Hash
+sha3_384 = _Hash
+sha3_512 = _Hash
+shake_128 = _VarLenHash
+shake_256 = _VarLenHash
+
+def scrypt(
+    password: ReadableBuffer,
+    *,
+    salt: Optional[ReadableBuffer] = ...,
+    n: Optional[int] = ...,
+    r: Optional[int] = ...,
+    p: Optional[int] = ...,
+    maxmem: int = ...,
+    dklen: int = ...,
+) -> bytes: ...
+
+class _BlakeHash(_Hash):
+    MAX_DIGEST_SIZE: int
+    MAX_KEY_SIZE: int
+    PERSON_SIZE: int
+    SALT_SIZE: int
+
+    if sys.version_info >= (3, 9):
+        def __init__(
+            self,
+            __data: ReadableBuffer = ...,
+            *,
+            digest_size: int = ...,
+            key: ReadableBuffer = ...,
+            salt: ReadableBuffer = ...,
+            person: ReadableBuffer = ...,
+            fanout: int = ...,
+            depth: int = ...,
+            leaf_size: int = ...,
+            node_offset: int = ...,
+            node_depth: int = ...,
+            inner_size: int = ...,
+            last_node: bool = ...,
+            usedforsecurity: bool = ...,
+        ) -> None: ...
+    else:
+        def __init__(
+            self,
+            __data: ReadableBuffer = ...,
+            *,
+            digest_size: int = ...,
+            key: ReadableBuffer = ...,
+            salt: ReadableBuffer = ...,
+            person: ReadableBuffer = ...,
+            fanout: int = ...,
+            depth: int = ...,
+            leaf_size: int = ...,
+            node_offset: int = ...,
+            node_depth: int = ...,
+            inner_size: int = ...,
+            last_node: bool = ...,
+        ) -> None: ...
+
+blake2b = _BlakeHash
+blake2s = _BlakeHash