Add symmetric key generation

1 files changed, 106 insertions, 0 deletions

diff --git a/lib/ncrypto_local.c b/lib/ncrypto_local.c
index 8f570b6..f311d63 100644
--- a/lib/ncrypto_local.c
+++ b/lib/ncrypto_local.c
@@ -86,6 +86,112 @@ ncr_symm_key_create (struct ncr_symm_key **key, CK_KEY_TYPE type,
   return CKR_OK;
 }
 
+/* Return non-zero if the key is unusable */
+#define DES_KEY_SIZE 8
+static int
+des3_fixup_key (uint8_t value[static 3 * DES_KEY_SIZE])
+{
+  static const uint8_t weak_keys[][DES_KEY_SIZE] =
+    {
+      "\x01\x01\x01\x01\x01\x01\x01\x01",
+      "\x1F\x1F\x1F\x1F\x0E\x0E\x0E\x0E",
+      "\xE0\xE0\xE0\xE0\xF1\xF1\xF1\xF1",
+      "\xFE\xFE\xFE\xFE\xFE\xFE\xFE\xFE",
+      "\x01\xFE\x01\xFE\x01\xFE\x01\xFE",
+      "\xFE\x01\xFE\x01\xFE\x01\xFE\x01",
+      "\x1F\xE0\x1F\xE0\x0E\xF1\x0E\xF1",
+      "\xE0\x1F\xE0\x1F\xF1\x0E\xF1\x0E",
+      "\x01\xE0\x01\xE0\x01\xF1\x01\xF1",
+      "\xE0\x01\xE0\x01\xF1\x01\xF1\x01",
+      "\x1F\xFE\x1F\xFE\x0E\xFE\x0E\xFE",
+      "\xFE\x1F\xFE\x1F\xFE\x0E\xFE\x0E",
+      "\x01\x1F\x01\x1F\x01\x0E\x01\x0E",
+      "\x1F\x01\x1F\x01\x0E\x01\x0E\x01",
+      "\xE0\xFE\xE0\xFE\xF1\xFE\xF1\xFE",
+      "\xFE\xE0\xFE\xE0\xFE\xF1\xFE\xF1"
+    };
+
+  size_t i;
+
+  for (i = 0; i < 3; i++)
+    {
+      uint8_t *key;
+      size_t j;
+
+      key = value + i * 8;
+      for (j = 0; j < DES_KEY_SIZE; j++)
+	{
+	  uint8_t v;
+
+	  v = key[i];
+	  v ^= v >> 4; /* v & 0x0F has the same parity as key[i] */
+	  v ^= v >> 2; /* v & 0x03 has the same parity as key[i] */
+	  v ^= v >> 1; /* v & 0x01 has the same parity as key[i] */
+	  key[i] ^= (v & 0x01) ^ 0x01; /* Ensure odd parity */
+	}
+      for (j = 0; j < G_N_ELEMENTS (weak_keys); j++)
+	{
+	  if (memcmp (key, weak_keys[j], DES_KEY_SIZE) == 0)
+	    return 1;
+	}
+    }
+  return 0;
+}
+#undef DES_KEY_SIZE
+
+CK_RV
+ncr_symm_key_generate (struct ncr_symm_key **key, CK_MECHANISM_TYPE mech,
+		       size_t value_size)
+{
+  struct ncr_symm_key *k;
+  CK_KEY_TYPE type;
+  CK_RV res;
+
+  g_return_val_if_fail (key != NULL, CKR_ARGUMENTS_BAD);
+  /* FIXME: PKCS#11 modules should refuse keys with incorrect parity here */
+
+  switch (mech)
+    {
+    case CKM_AES_KEY_GEN:
+      type = CKK_AES;
+      g_return_val_if_fail (value_size == 16 || value_size == 24
+			    || value_size == 32, CKR_TEMPLATE_INCONSISTENT);
+      break;
+
+    case CKM_DES3_KEY_GEN:
+      type = CKK_DES3;
+      g_return_val_if_fail (value_size == 24 || value_size == 0,
+			    CKR_TEMPLATE_INCONSISTENT);
+      value_size = 24;
+      break;
+
+    default:
+      g_return_val_if_reached (CKR_MECHANISM_INVALID);
+    }
+  k = malloc (sizeof (*k) + value_size);
+  if (k == NULL)
+    return CKR_HOST_MEMORY;
+
+  k->type = type;
+  k->size = value_size;
+ regenerate:
+  res = ncr_get_random_bytes (k->value, value_size);
+  if (res != CKR_OK)
+    {
+      ncr_symm_key_destroy (k);
+      return res;
+    }
+
+  if (type == CKK_DES3)
+    {
+      if (des3_fixup_key (k->value) != 0)
+	goto regenerate;
+    }
+
+  *key = k;
+  return CKR_OK;
+}
+
 CK_RV
 ncr_symm_key_destroy (struct ncr_symm_key *key)
 {