mpint: add a few simple bitwise operations.

I want to use mp_xor_into as part of an upcoming test program, and
while I'm at it, I thought I'd add a few other obvious bitops too.

mpint.c

@@ -692,6 +692,38 @@ void mp_sub_into(mp_int *r, mp_int *a, mp_int *b)
     mp_add_masked_into(r->w, r->nw, a, b, ~(BignumInt)0, ~(BignumInt)0, 1);
 }
 
+void mp_and_into(mp_int *r, mp_int *a, mp_int *b)
+{
+    for (size_t i = 0; i < r->nw; i++) {
+        BignumInt aword = mp_word(a, i), bword = mp_word(b, i);
+        r->w[i] = aword & bword;
+    }
+}
+
+void mp_or_into(mp_int *r, mp_int *a, mp_int *b)
+{
+    for (size_t i = 0; i < r->nw; i++) {
+        BignumInt aword = mp_word(a, i), bword = mp_word(b, i);
+        r->w[i] = aword | bword;
+    }
+}
+
+void mp_xor_into(mp_int *r, mp_int *a, mp_int *b)
+{
+    for (size_t i = 0; i < r->nw; i++) {
+        BignumInt aword = mp_word(a, i), bword = mp_word(b, i);
+        r->w[i] = aword ^ bword;
+    }
+}
+
+void mp_bic_into(mp_int *r, mp_int *a, mp_int *b)
+{
+    for (size_t i = 0; i < r->nw; i++) {
+        BignumInt aword = mp_word(a, i), bword = mp_word(b, i);
+        r->w[i] = aword & ~bword;
+    }
+}
+
 static void mp_cond_negate(mp_int *r, mp_int *x, unsigned yes)
 {
     BignumCarry carry = yes;

mpint.h

@@ -197,6 +197,14 @@ mp_int *mp_add(mp_int *x, mp_int *y);
 mp_int *mp_sub(mp_int *x, mp_int *y);
 mp_int *mp_mul(mp_int *x, mp_int *y);
 
+/*
+ * Bitwise operations.
+ */
+void mp_and_into(mp_int *r, mp_int *a, mp_int *b);
+void mp_or_into(mp_int *r, mp_int *a, mp_int *b);
+void mp_xor_into(mp_int *r, mp_int *a, mp_int *b);
+void mp_bic_into(mp_int *r, mp_int *a, mp_int *b);
+
 /*
  * Addition, subtraction and multiplication with one argument small
  * enough to fit in a C integer. For mp_mul_integer_into, it has to be

test/cryptsuite.py

@@ -367,6 +367,23 @@ class mpint(MyTestBase):
                     self.assertEqual(int(mp_div(n, d)), q)
                     self.assertEqual(int(mp_mod(n, d)), r)
 
+    def testBitwise(self):
+        p = 0x3243f6a8885a308d313198a2e03707344a4093822299f31d0082efa98ec4e
+        e = 0x2b7e151628aed2a6abf7158809cf4f3c762e7160f38b4da56a784d9045190
+        x = mp_new(nbits(p))
+
+        mp_and_into(x, p, e)
+        self.assertEqual(int(x), p & e)
+
+        mp_or_into(x, p, e)
+        self.assertEqual(int(x), p | e)
+
+        mp_xor_into(x, p, e)
+        self.assertEqual(int(x), p ^ e)
+
+        mp_bic_into(x, p, e)
+        self.assertEqual(int(x), p & ~e)
+
     def testInversion(self):
         # Test mp_invert_mod_2to.
         testnumbers = [(mp_copy(n),n) for n in fibonacci_scattered()

testcrypt.h

@@ -37,6 +37,10 @@ FUNC3(void, mp_mul_into, val_mpint, val_mpint, val_mpint)
 FUNC2(val_mpint, mp_add, val_mpint, val_mpint)
 FUNC2(val_mpint, mp_sub, val_mpint, val_mpint)
 FUNC2(val_mpint, mp_mul, val_mpint, val_mpint)
+FUNC3(void, mp_and_into, val_mpint, val_mpint, val_mpint)
+FUNC3(void, mp_or_into, val_mpint, val_mpint, val_mpint)
+FUNC3(void, mp_xor_into, val_mpint, val_mpint, val_mpint)
+FUNC3(void, mp_bic_into, val_mpint, val_mpint, val_mpint)
 FUNC3(void, mp_add_integer_into, val_mpint, val_mpint, uint)
 FUNC3(void, mp_sub_integer_into, val_mpint, val_mpint, uint)
 FUNC3(void, mp_mul_integer_into, val_mpint, val_mpint, uint)