Add ncr_public_key_export

2 files changed, 88 insertions, 0 deletions

diff --git a/include/ncrypto/ncrypto.h b/include/ncrypto/ncrypto.h
index a09d451..c4de81e 100644
--- a/include/ncrypto/ncrypto.h
+++ b/include/ncrypto/ncrypto.h
@@ -73,6 +73,8 @@ struct ncr_private_key;
 
 CK_RV ncr_public_key_create (struct ncr_public_key **key, CK_KEY_TYPE type,
 			     const void *der, size_t der_size);
+CK_RV ncr_public_key_export (struct ncr_public_key *key, void *dest,
+			     size_t *dest_size_ptr);
 CK_RV ncr_public_key_destroy (struct ncr_public_key *key);
 CK_RV ncr_private_key_create (struct ncr_private_key **key, CK_KEY_TYPE type,
 			      const void *der, size_t der_size,
diff --git a/lib/ncrypto_nss.c b/lib/ncrypto_nss.c
index 2c806c4..71f63bc 100644
--- a/lib/ncrypto_nss.c
+++ b/lib/ncrypto_nss.c
@@ -146,6 +146,92 @@ public_key_create (struct ncr_public_key **key, CK_KEY_TYPE type,
 }
 
 CK_RV
+ncr_public_key_export (struct ncr_public_key *key, void *dest,
+		       size_t *dest_size_ptr)
+{
+  struct subject_pub_key_info
+  {
+    SECAlgorithmID algorithm;
+    SECItem pub_key;
+  };
+
+  static const SEC_ASN1Template asn1_template[] =
+    {
+      { SEC_ASN1_SEQUENCE, 0, NULL, sizeof (struct subject_pub_key_info) },
+      {
+	SEC_ASN1_INLINE, offsetof (struct subject_pub_key_info, algorithm),
+	SECOID_AlgorithmIDTemplate, 0,
+      },
+      {
+	SEC_ASN1_BIT_STRING, offsetof (struct subject_pub_key_info, pub_key),
+	NULL, 0,
+      },
+      { 0, 0, NULL, 0 }
+    };
+
+  struct subject_pub_key_info der_output;
+  PRArenaPool *arena;
+  SECItem *der_key;
+  size_t dest_size;
+  CK_RV res;
+
+  res = ensure_ncr_is_open ();
+  if (res != CKR_OK)
+    return res;
+
+  g_return_val_if_fail (key != NULL, CKR_ARGUMENTS_BAD);
+  g_return_val_if_fail (dest_size_ptr != NULL, CKR_ARGUMENTS_BAD);
+
+  der_key = SECKEY_EncodeDERSubjectPublicKeyInfo (key->key);
+  if (der_key == NULL)
+    return CKR_GENERAL_ERROR;
+
+  /* Ugly... the PLArenaPool type is from NSPR, but NSS implementation accesses
+     memory only initialized through NSS's PORT_* */
+  arena = PORT_NewArena (SEC_ASN1_DEFAULT_ARENA_SIZE);
+  if (arena == NULL)
+    {
+      res = CKR_HOST_MEMORY;
+      goto end_der_key;
+    }
+
+  if (SEC_QuickDERDecodeItem (arena, &der_output, asn1_template, der_key)
+      != SECSuccess)
+    {
+      res = CKR_GENERAL_ERROR;
+      goto end_arena;
+    }
+
+  /* der_output.pub_key is encoded as BIT_STRING, so pub_key.len is a number of
+     _bits_.  */
+  dest_size = der_output.pub_key.len / 8;
+  if (der_output.pub_key.len % 8 != 0)
+    dest_size ++;
+  if (dest == NULL)
+    {
+      *dest_size_ptr = dest_size;
+      res = CKR_OK;
+      goto end_arena;
+    }
+  if (*dest_size_ptr < dest_size)
+    {
+      *dest_size_ptr = dest_size;
+      res = CKR_BUFFER_TOO_SMALL;
+      goto end_arena;
+    }
+  *dest_size_ptr = dest_size;
+
+  memcpy (dest, der_output.pub_key.data, dest_size);
+  res = CKR_OK;
+
+ end_arena:
+  PORT_FreeArena (arena, PR_FALSE);
+ end_der_key:
+  SECITEM_FreeItem (der_key, PR_TRUE);
+  return res;
+}
+
+CK_RV
 ncr_public_key_create (struct ncr_public_key **key, CK_KEY_TYPE type,
 		       const void *der, size_t der_size)
 {