diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index 2721c50..6ced031 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -1273,6 +1273,28 @@ ykpiv_rc ykpiv_import_private_key(ykpiv_state *state, const unsigned char key, u
 
 }
 
+ykpiv_rc ykpiv_attest(ykpiv_state *state, int object_id, unsigned char *data, size_t *data_len) {
+  ykpiv_rc res;
+  bool ret = false;
+  unsigned char templ[] = {0, YKPIV_INS_ATTEST, object_id, 0};
+  int sw;
+
+  if (state == NULL || data == NULL || data_len == NULL) {
+    return YKPIV_ARGUMENT_ERROR;
+  }
+  if ((res = ykpiv_transfer_data(state, templ, NULL, 0, data, data_len, &sw)) != YKPIV_OK) {
+    return res;
+  }
+  else if(SW_SUCCESS != sw) {
+    return YKPIV_GENERIC_ERROR;
+  }
+  if (data[0] != 0x30) {
+    return YKPIV_GENERIC_ERROR;
+  }
+  return YKPIV_OK;
+}
+
+
 // TREV TODO: remove these, fix minidriver
 
 ykpiv_rc ykpiv_done2(ykpiv_state *state, bool disconnect) {
diff --git a/lib/ykpiv.h b/lib/ykpiv.h
index 28d2a73..6e14328 100644
--- a/lib/ykpiv.h
+++ b/lib/ykpiv.h
@@ -126,6 +126,7 @@ extern "C"
   ykpiv_rc ykpiv_get_pin_retries(ykpiv_state *state, int* tries);
   // TREV TODO: document that 0 == successful no-op.
   ykpiv_rc ykpiv_set_pin_retries(ykpiv_state *state, int pin_tries, int puk_tries);
+  ykpiv_rc ykpiv_attest(ykpiv_state *state, int object_id, unsigned char *data, size_t *data_len);
 
 #define YKPIV_ALGO_TAG 0x80
 #define YKPIV_ALGO_3DES 0x03
diff --git a/tool/yubico-piv-tool.c b/tool/yubico-piv-tool.c
index c0affd5..af32edf 100644
--- a/tool/yubico-piv-tool.c
+++ b/tool/yubico-piv-tool.c
@@ -1604,55 +1604,45 @@ static bool list_readers(ykpiv_state *state) {
 
 static bool attest(ykpiv_state *state, const char *slot,
     enum enum_key_format key_format, const char *output_file_name) {
-  unsigned char data[2048];
+  unsigned char data[YKPIV_OBJ_MAX_SIZE];
   unsigned long len = sizeof(data);
   bool ret = false;
   X509 *x509 = NULL;
-  unsigned char templ[] = {0, YKPIV_INS_ATTEST, 0, 0};
   int key;
-  int sw;
   FILE *output_file = open_file(output_file_name, OUTPUT);
   if(!output_file) {
     return false;
   }
 
-  sscanf(slot, "%2x", &key);
-  templ[2] = key;
-
   if(key_format != key_format_arg_PEM && key_format != key_format_arg_DER) {
     fprintf(stderr, "Only PEM and DER format are supported for attest..\n");
     return false;
   }
 
-  if(ykpiv_transfer_data(state, templ, NULL, 0, data, &len, &sw) != YKPIV_OK) {
-    fprintf(stderr, "Failed to communicate.\n");
-    goto attest_out;
-  } else if(sw != SW_SUCCESS) {
-    fprintf(stderr, "Failed to attest key.\n");
+  sscanf(slot, "%2x", &key);
+  if (ykpiv_attest(state, key, data, &len) != YKPIV_OK) {
+    fprintf(stderr, "Failed to attest data.\n");
     goto attest_out;
   }
 
-  if(data[0] == 0x30) {
-    if(key_format == key_format_arg_PEM) {
-      const unsigned char *ptr = data;
-      int len2 = len;
-      x509 = X509_new();
-      if(!x509) {
-        fprintf(stderr, "Failed allocating x509 structure.\n");
-        goto attest_out;
-      }
-      x509 = d2i_X509(NULL, &ptr, len2);
-      if(!x509) {
-        fprintf(stderr, "Failed parsing x509 information.\n");
-        goto attest_out;
-      }
-      PEM_write_X509(output_file, x509);
-      ret = true;
-    } else {
-      fwrite(data, len, 1, output_file);
+  if(key_format == key_format_arg_PEM) {
+    const unsigned char *ptr = data;
+    int len2 = len;
+    x509 = X509_new();
+    if(!x509) {
+      fprintf(stderr, "Failed allocating x509 structure.\n");
+      goto attest_out;
     }
-    ret = true;
+    x509 = d2i_X509(NULL, &ptr, len2);
+    if(!x509) {
+      fprintf(stderr, "Failed parsing x509 information.\n");
+      goto attest_out;
+    }
+    PEM_write_X509(output_file, x509);
+  } else {
+    fwrite(data, len, 1, output_file);
   }
+  ret = true;
 
 attest_out:
   if(output_file != stdout) {