First commit with the first homework assignment.HEADmaster

1 files changed, 75 insertions, 0 deletions

diff --git a/assignment1/exercise1_2.c b/assignment1/exercise1_2.c
new file mode 100644
index 0000000..fea4230
--- /dev/null
+++ b/assignment1/exercise1_2.c
@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+
+typedef unsigned char poly8;
+typedef unsigned long long poly8x64[8];
+
+void poly8_bitslice(poly8x64 r, const poly8 x[64])
+{
+  /* TODO implement */
+}
+
+/* reduction polynomial x^8 + x^4 + x^3 + x + 1 */
+void poly8x64_mulmod(poly8x64 r, const poly8x64 a, const poly8x64 b)
+{
+  /* TODO implement */
+}
+
+void poly8x64_unbitslice(poly8 r[64], const poly8x64 x)
+{
+  /* TODO implement */
+}
+
+static void poly8mod_print(const poly8 x)
+{
+  int i;
+  int d=0;
+  printf("Mod(");
+  for(i=0;i<8;i++)
+    if(1&(x>>i))
+    {
+      if(d) printf(" + ");
+      printf("Mod(1,2)*X^%d",i);
+      d = 1;
+    }
+  if(d==0) printf("Mod(0,2)");
+  printf(",Mod(1,2)*X^8+Mod(1,2)*X^4+Mod(1,2)*X^3+Mod(1,2)*X+Mod(1,2))");
+}
+
+
+/* Pipe output through gp */
+int main()
+{
+
+  poly8 a[64], b[64], r[64];
+  poly8x64 va, vb, vt;
+  int i;
+
+  FILE *urandom = fopen("/dev/urandom","r");
+  for(i=0;i<64;i++)
+  {
+    a[i] = fgetc(urandom);
+    b[i] = fgetc(urandom);
+  }
+
+  poly8_bitslice(va, a);
+  poly8_bitslice(vb, b);
+
+  poly8x64_mulmod(vt,va,vb);
+  poly8x64_unbitslice(r,vt);
+
+  for(i=0;i<64;i++)
+  {
+    printf("centerlift(centerlift(");
+    poly8mod_print(a[i]);
+    printf(" * ");
+    poly8mod_print(b[i]);
+    printf(" - ");
+    poly8mod_print(r[i]);
+    printf("))\n");
+  }
+  
+  fclose(urandom);
+  return 0;
+}