python-crypto: Fix two CVEs

CVE-2013-7459 and CVE-2018-6594. Both patches taken from Fedora.

Also took the liberty to update the PKG_SOURCE_URL to a standard one.

Updated the home URL as well.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

lang/python/python-crypto/patches/101-CVE-2018-6594.patch

@@ -0,0 +1,51 @@
+--- lib/Crypto/PublicKey/ElGamal.py
++++ lib/Crypto/PublicKey/ElGamal.py
+@@ -153,33 +153,33 @@ def generate(bits, randfunc, progress_fu
+         if number.isPrime(obj.p, randfunc=randfunc):
+             break
+     # Generate generator g
+-    # See Algorithm 4.80 in Handbook of Applied Cryptography
+-    # Note that the order of the group is n=p-1=2q, where q is prime
+     if progress_func:
+         progress_func('g\n')
+     while 1:
++        # Choose a square residue; it will generate a cyclic group of order q.
++        obj.g = pow(number.getRandomRange(2, obj.p, randfunc), 2, obj.p)
++
+         # We must avoid g=2 because of Bleichenbacher's attack described
+         # in "Generating ElGamal signatures without knowning the secret key",
+         # 1996
+-        #
+-        obj.g = number.getRandomRange(3, obj.p, randfunc)
+-        safe = 1
+-        if pow(obj.g, 2, obj.p)==1:
+-            safe=0
+-        if safe and pow(obj.g, q, obj.p)==1:
+-            safe=0
++        if obj.g in (1, 2):
++            continue
++
+         # Discard g if it divides p-1 because of the attack described
+         # in Note 11.67 (iii) in HAC
+-        if safe and divmod(obj.p-1, obj.g)[1]==0:
+-            safe=0
++        if (obj.p - 1) % obj.g == 0:
++            continue
++
+         # g^{-1} must not divide p-1 because of Khadir's attack
+         # described in "Conditions of the generator for forging ElGamal
+         # signature", 2011
+         ginv = number.inverse(obj.g, obj.p)
+-        if safe and divmod(obj.p-1, ginv)[1]==0:
+-            safe=0
+-        if safe:
+-            break
++        if (obj.p - 1) % ginv == 0:
++            continue
++
++        # Found
++        break
++
+     # Generate private key x
+     if progress_func:
+         progress_func('x\n')