Hash: Speed up initialization by removing pure-Python wrappershash-speedup-wip

The pure Python wrappers around Crypto.Hash.* were convenient, but they
slowed down hash initialization by 4-7x.

There is a speed trade-off here: The MD5 and SHA1 objects are just
wrapped hashlib objects (or old-style md5/sha objects).  To maintain API
compatibility with the rest of PyCrypto, we still have to wrap them, so
they're slower to initialize than the rest of the hash functions.  If
hashlib ever adds a .new() method, we will automatically use hashlib
directly and gain the initialization speed-up.

1 files changed, 16 insertions, 3 deletions

diff --git a/lib/Crypto/Signature/PKCS1_PSS.py b/lib/Crypto/Signature/PKCS1_PSS.py
index cd9eaf3..3840959 100644
--- a/lib/Crypto/Signature/PKCS1_PSS.py
+++ b/lib/Crypto/Signature/PKCS1_PSS.py
@@ -72,6 +72,7 @@ if sys.version_info[0] == 2 and sys.version_info[1] == 1:
 import Crypto.Util.number
 from Crypto.Util.number import ceil_shift, ceil_div, long_to_bytes
 from Crypto.Util.strxor import strxor
+from Crypto.Hash import new as Hash_new
 
 class PSS_SigScheme:
     """This signature scheme can perform PKCS#1 PSS RSA signature or verification."""
@@ -203,7 +204,11 @@ def MGF1(mgfSeed, maskLen, hash):
     T = b("")
     for counter in xrange(ceil_div(maskLen, hash.digest_size)):
         c = long_to_bytes(counter, 4)
-        T = T + hash.new(mgfSeed + c).digest()
+        try:
+            T = T + hash.new(mgfSeed + c).digest()
+        except AttributeError:
+            # hash object doesn't have a "new" method.  Use Crypto.Hash.new() to instantiate it
+            T = T + Hash_new(hash, mgfSeed + c).digest()
     assert(len(T)>=maskLen)
     return T[:maskLen]
 
@@ -253,7 +258,11 @@ def EMSA_PSS_ENCODE(mhash, emBits, randFunc, mgf, sLen):
     if randFunc and sLen>0:
         salt = randFunc(sLen)
     # Step 5 and 6
-    h = mhash.new(bchr(0x00)*8 + mhash.digest() + salt)
+    try:
+        h = mhash.new(bchr(0x00)*8 + mhash.digest() + salt)
+    except AttributeError:
+        # hash object doesn't have a "new" method.  Use Crypto.Hash.new() to instantiate it
+        h = Hash_new(mhash, bchr(0x00)*8 + mhash.digest() + salt)
     # Step 7 and 8
     db = bchr(0x00)*(emLen-sLen-mhash.digest_size-2) + bchr(0x01) + salt
     # Step 9
@@ -328,7 +337,11 @@ def EMSA_PSS_VERIFY(mhash, em, emBits, mgf, sLen):
     salt = b("")
     if sLen: salt = db[-sLen:]
     # Step 12 and 13
-    hp = mhash.new(bchr(0x00)*8 + mhash.digest() + salt).digest()
+    try:
+        hp = mhash.new(bchr(0x00)*8 + mhash.digest() + salt).digest()
+    except AttributeError:
+        # hash object doesn't have a "new" method.  Use Crypto.Hash.new() to instantiate it
+        hp = Hash_new(mhash, bchr(0x00)*8 + mhash.digest() + salt).digest()
     # Step 14
     if h!=hp:
         return False