- poly1305_update(&ctx, m, bytes);
- poly1305_finish(&ctx, mac);
+ memset(&pad, 0, sizeof(pad));
+
+ /* payload and padding */
+ poly1305_update(&ctx, ct, ct_len);
+ left_over = ct_len % 16;
+
+ if(left_over) {
+ poly1305_update(&ctx, pad, 16 - left_over);
+ }
+
+ /* lengths */
+ len = 0;
+ poly1305_update(&ctx, (unsigned char *)&len, 8);
+ len = ct_len;
+ poly1305_update(&ctx, (unsigned char *)&len, 8);
+ poly1305_finish(&ctx, tag);