diff options
| -rw-r--r-- | Lib/hmac.py | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/Lib/hmac.py b/Lib/hmac.py index db9b404..11b0fb3 100644 --- a/Lib/hmac.py +++ b/Lib/hmac.py @@ -12,6 +12,11 @@ def _strxor(s1, s2): # hashing module used. digest_size = None +# A unique object passed by HMAC.copy() to the HMAC constructor, in order +# that the latter return very quickly. HMAC("") in contrast is quite +# expensive. +_secret_backdoor_key = [] + class HMAC: """RFC2104 HMAC class. @@ -25,6 +30,10 @@ class HMAC: msg: Initial input for the hash, if provided. digestmod: A module supporting PEP 247. Defaults to the md5 module. """ + + if key is _secret_backdoor_key: # cheap + return + if digestmod is None: import md5 digestmod = md5 @@ -60,8 +69,9 @@ class HMAC: An update to this copy won't affect the original object. """ - other = HMAC("") + other = HMAC(_secret_backdoor_key) other.digestmod = self.digestmod + other.digest_size = self.digest_size other.inner = self.inner.copy() other.outer = self.outer.copy() return other |