Add set_params function, last part of bug 5519.

git-svn-id: http://svn.osafoundation.org/m2crypto/trunk@442 2715db39-9adf-0310-9c64-84f055769b4b

2 files changed, 28 insertions, 0 deletions

diff --git a/M2Crypto/DSA.py b/M2Crypto/DSA.py
index c428cd5..cacee88 100644
--- a/M2Crypto/DSA.py
+++ b/M2Crypto/DSA.py
@@ -291,6 +291,25 @@ def gen_params(bits, callback=util.genparam_callback):
         raise DSAError('problem generating DSA parameters')
     return DSA(dsa, 1)
 
+def set_params(p, q, g):
+    """
+    Factory function that instantiates a DSA object with DSA
+    parameters.
+
+    @type  p: str
+    @param p: value of p, a "byte string"
+    @type  q: str
+    @param q: value of q, a "byte string"
+    @type  g: str
+    @param g: value of g, a "byte string"
+    @rtype:   DSA
+    @return:  instance of DSA.
+    """
+    dsa = m2.dsa_new()
+    m2.dsa_set_p(dsa, p)
+    m2.dsa_set_q(dsa, q)
+    m2.dsa_set_g(dsa, g)
+    return DSA(dsa, 1)
 
 def load_params(file, callback=util.passphrase_callback):
     """
diff --git a/tests/test_dsa.py b/tests/test_dsa.py
index c919122..25ef667 100644
--- a/tests/test_dsa.py
+++ b/tests/test_dsa.py
@@ -73,6 +73,15 @@ class DSATestCase(unittest.TestCase):
     def check_genparam_setparam_genkey(self):
         dsa = DSA.gen_params(256, self.callback)
         assert len(dsa) == 512
+        p = dsa.p
+        q = dsa.q
+        g = dsa.g
+        dsa2 = DSA.set_params(p,q,g)
+        assert not dsa2.check_key()
+        dsa2.gen_key()
+        assert dsa2.check_key()
+        r,s = dsa2.sign(self.data)
+        assert dsa2.verify(self.data, r, s)
 
 def suite():
     return unittest.makeSuite(DSATestCase, 'check')