def __init__(self, name, copy_from=None):
self.ctx = ffi.NULL
self.name = name
digest_type = self.digest_type_by_name()
self.digest_size = lib.EVP_MD_size(digest_type)
# Allocate a lock for each HASH object.
# An optimization would be to not release the GIL on small requests,
# and use a custom lock only when needed.
self.lock = Lock()
ctx = lib.Cryptography_EVP_MD_CTX_new()
if ctx == ffi.NULL:
raise MemoryError
ctx = ffi.gc(ctx, lib.Cryptography_EVP_MD_CTX_free)
try:
if copy_from is not None:
# cpython uses EVP_MD_CTX_copy(...)
if not lib.EVP_MD_CTX_copy_ex(ctx, copy_from):
raise ValueError
else:
# cpython uses EVP_DigestInit
lib.EVP_DigestInit_ex(ctx, digest_type, ffi.NULL)
self.ctx = ctx
except:
# no need to gc ctx!
raise
def pbkdf2_hmac(hash_name, password, salt, iterations, dklen=None):
if not isinstance(hash_name, str):
raise TypeError("expected 'str' for name, but got %s" % type(hash_name))
c_name = _str_to_ffi_buffer(hash_name)
digest = lib.EVP_get_digestbyname(c_name)
if digest == ffi.NULL:
raise ValueError("unsupported hash type")
if dklen is None:
dklen = lib.EVP_MD_size(digest)
if dklen < 1:
raise ValueError("key length must be greater than 0.")
if dklen >= sys.maxsize:
raise OverflowError("key length is too great.")
if iterations < 1:
raise ValueError("iteration value must be greater than 0.")
if iterations >= sys.maxsize:
raise OverflowError("iteration value is too great.")
buf = ffi.new("unsigned char[]", dklen)
c_password = ffi.from_buffer(bytes(password))
c_salt = ffi.from_buffer(bytes(salt))
r = lib.PKCS5_PBKDF2_HMAC(c_password, len(c_password),
ffi.cast("unsigned char*",c_salt), len(c_salt),
iterations, digest, dklen, buf)
if r == 0:
raise ValueError
return _bytes_with_len(buf, dklen)
