Issue #13703: add a way to randomize the hash values of basic types (str, bytes, datetime)
in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.
The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.
diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index 0ac51aa..f3103ea 100644
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -2566,10 +2566,12 @@
register long x;
p = (unsigned char *) data;
- x = *p << 7;
+ x = _Py_HashSecret.prefix;
+ x ^= *p << 7;
while (--len >= 0)
x = (1000003*x) ^ *p++;
x ^= len;
+ x ^= _Py_HashSecret.suffix;
if (x == -1)
x = -2;