diff --git a/dap-sdk/crypto/src/dap_cert.c b/dap-sdk/crypto/src/dap_cert.c
index 4b9d0e35a417f366e8e95f35f8b5a94a00eb0f40..f813c276d6c9b3d1b66f57a20bc04ca374bf1bd2 100755
--- a/dap-sdk/crypto/src/dap_cert.c
+++ b/dap-sdk/crypto/src/dap_cert.c
@@ -82,11 +82,13 @@ int dap_cert_init()
 }
 
 /**
- * @brief dap_cert_parse_str_list
- * @param a_certs_str
- * @param a_certs
- * @param a_certs_size_t
- * @return summary size for signatures of all certs in list
+ * @brief 
+ * parse list of certificate from config file (if it is presented)
+ * in current implementation this function is used when node certificate (node-addr.dcert) is not generated 
+ * @param a_certs_str const char * string with certificate name (node-addr)
+ * @param a_certs dap_cert_t *** array with certificates
+ * @param a_certs_size size of certificate
+ * @return size_t 
  */
 size_t dap_cert_parse_str_list(const char * a_certs_str, dap_cert_t *** a_certs, size_t * a_certs_size)
 {
@@ -134,10 +136,11 @@ size_t dap_cert_parse_str_list(const char * a_certs_str, dap_cert_t *** a_certs,
 
 
 /**
- * @brief dap_cert_sign_output_size
- * @param a_cert
- * @param a_size_wished
- * @return
+ * @brief 
+ * simply call dap_sign_create_output_unserialized_calc_size( a_cert->enc_key,a_size_wished)
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_size_wished wished data size (don't used in current implementation)
+ * @return size_t 
  */
 size_t dap_cert_sign_output_size(dap_cert_t * a_cert, size_t a_size_wished)
 {
@@ -160,12 +163,13 @@ size_t dap_cert_sign_output_size(dap_cert_t * a_cert, size_t a_size_wished)
 }*/
 
 /**
- * @brief dap_cert_sign
- * @param a_cert
- * @param a_data
- * @param a_data_size
- * @param a_output_size_wished
- * @return
+ * @brief 
+ * sign data by encryption key from certificate
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_data data for signing
+ * @param a_data_size data size
+ * @param a_output_size_wished wished data size (don't used in current implementation)
+ * @return dap_sign_t* 
  */
 dap_sign_t * dap_cert_sign(dap_cert_t * a_cert, const void * a_data
                                        , size_t a_data_size, size_t a_output_size_wished )
@@ -176,10 +180,11 @@ dap_sign_t * dap_cert_sign(dap_cert_t * a_cert, const void * a_data
 }
 
 /**
- * @brief dap_cert_add_cert_sign
- * @param a_cert
- * @param a_cert_signer
- * @return
+ * @brief 
+ * sign certificate with another certificate (a_cert->signs)
+ * @param a_cert dap_cert_t certificate object
+ * @param a_cert_signer dap_cert_t certificate object, which signs a_cert
+ * @return int 
  */
 int dap_cert_add_cert_sign(dap_cert_t * a_cert, dap_cert_t * a_cert_signer)
 {
@@ -196,10 +201,13 @@ int dap_cert_add_cert_sign(dap_cert_t * a_cert, dap_cert_t * a_cert_signer)
 
 
 /**
- * @brief dap_cert_generate_mem
- * @param a_cert_name
- * @param a_key_type
- * @return
+ * @brief generate certificate in memory with specified seed
+ * 
+ * @param a_cert_name const char * name of certificate
+ * @param a_key_type dap_enc_key_type_t key type
+ * @param a_seed const void* seed for certificate generation
+ * @param a_seed_size size_t size of seed
+ * @return dap_cert_t* 
  */
 dap_cert_t * dap_cert_generate_mem_with_seed(const char * a_cert_name, dap_enc_key_type_t a_key_type,
         const void* a_seed, size_t a_seed_size)
@@ -222,10 +230,11 @@ dap_cert_t * dap_cert_generate_mem_with_seed(const char * a_cert_name, dap_enc_k
 }
 
 /**
- * @brief dap_cert_generate_mem
- * @param a_cert_name
- * @param a_key_type
- * @return
+ * @brief generate certificate in memory
+ * 
+ * @param a_cert_name const char * certificate name
+ * @param a_key_type encryption key type
+ * @return dap_cert_t* 
  */
 dap_cert_t * dap_cert_generate_mem(const char * a_cert_name, dap_enc_key_type_t a_key_type)
 {
@@ -233,11 +242,12 @@ dap_cert_t * dap_cert_generate_mem(const char * a_cert_name, dap_enc_key_type_t
 }
 
 /**
- * @brief dap_cert_generate
- * @param a_cert_name
- * @param a_file_path
- * @param a_key_type
- * @return
+ * @brief generate certificate and save it to file
+ * 
+ * @param a_cert_name const char * certificate name
+ * @param a_file_path const char * path to certificate file
+ * @param a_key_type dap_enc_key_type_t key_type
+ * @return dap_cert_t* 
  */
 dap_cert_t * dap_cert_generate(const char * a_cert_name
                                            , const char * a_file_path,dap_enc_key_type_t a_key_type )
@@ -259,7 +269,8 @@ dap_cert_t * dap_cert_generate(const char * a_cert_name
 
 /**
  * @brief dap_cert_delete_by_name
- * @param a_cert_name
+ * delete certificate object, finding by name
+ * @param a_cert_name const char * certificate name
  */
 void dap_cert_delete_by_name(const char * a_cert_name)
 {
@@ -271,8 +282,9 @@ void dap_cert_delete_by_name(const char * a_cert_name)
 }
 
 /**
- * @brief dap_cert_find_by_name
- * @param a_cert_name
+ * @brief
+ * find certificate by name in path, which is configured ca_folders parameter in chain config 
+ * @param a_cert_name const char *
  * @return
  */
 dap_cert_t * dap_cert_find_by_name(const char * a_cert_name)
@@ -313,7 +325,8 @@ dap_list_t *dap_cert_get_all_mem()
 
 /**
  * @brief dap_cert_new
- * @param a_name
+ * create certificate object with specified name
+ * @param a_name const char *
  * @return
  */
 dap_cert_t * dap_cert_new(const char * a_name)
@@ -332,7 +345,8 @@ dap_cert_t * dap_cert_new(const char * a_name)
 
 /**
  * @brief s_cert_delete
- * @param a_cert
+ * delete certificate object
+ * @param a_cert dap_cert_t *
  */
 void dap_cert_delete(dap_cert_t * a_cert)
 {
@@ -354,9 +368,10 @@ void dap_cert_delete(dap_cert_t * a_cert)
 
 /**
  * @brief dap_cert_add_file
- * @param a_cert_name
- * @param a_folder_path
- * @return
+ * load certificate file from folder (specified in chain config)
+ * @param a_cert_name const char * certificate name
+ * @param a_folder_path const char * certificate path
+ * @return dap_cert_t
  */
 dap_cert_t * dap_cert_add_file(const char * a_cert_name,const char *a_folder_path)
 {
@@ -378,9 +393,11 @@ dap_cert_t * dap_cert_add_file(const char * a_cert_name,const char *a_folder_pat
 }
 
 /**
- * @brief dap_cert_save_to_folder
- * @param a_cert
- * @param a_file_dir_path
+ * @brief save certitificate to folder
+ * 
+ * @param a_cert dap_cert_t * certiticate object
+ * @param a_file_dir_path const char * path to directory with certificate
+ * @return int 
  */
 int dap_cert_save_to_folder(dap_cert_t * a_cert, const char *a_file_dir_path)
 {
@@ -396,8 +413,10 @@ int dap_cert_save_to_folder(dap_cert_t * a_cert, const char *a_file_dir_path)
 
 /**
  * @brief dap_cert_to_pkey
- * @param a_cert
- * @return
+ * get public key from certificate 
+ *  dap_pkey_from_enc_key( a_cert->enc_key )
+ * @param a_cert dap_cert_t certificate object
+ * @return dap_pkey_t
  */
 dap_pkey_t * dap_cert_to_pkey(dap_cert_t * a_cert)
 {
@@ -408,10 +427,11 @@ dap_pkey_t * dap_cert_to_pkey(dap_cert_t * a_cert)
 }
 
 /**
- * @brief dap_cert_compare_with_sign
- * @param a_cert
- * @param a_sign
- * @return
+ * @brief 
+ * compare certificate encryption key with key, which was used for event or block signing
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_sign dap_sign_t * dap_sign_t object (signed block or event)
+ * @return int 
  */
 int dap_cert_compare_with_sign (dap_cert_t * a_cert,const dap_sign_t * a_sign)
 {
@@ -434,8 +454,8 @@ int dap_cert_compare_with_sign (dap_cert_t * a_cert,const dap_sign_t * a_sign)
 
 
 /**
- * @brief dap_cert_count_cert_sign
- * @param a_cert
+ * @brief Certificates signatures chain size
+ * @param a_cert dap_cert_t certificate object
  * @return
  */
 size_t dap_cert_count_cert_sign(dap_cert_t * a_cert)
@@ -448,8 +468,8 @@ size_t dap_cert_count_cert_sign(dap_cert_t * a_cert)
 
 
 /**
- * @brief dap_cert_dump
- * @param a_cert
+ * @brief show certificate information
+ * @param a_cert dap_cert_t certificate object
  */
 void dap_cert_dump(dap_cert_t * a_cert)
 {
@@ -491,8 +511,10 @@ void dap_cert_dump(dap_cert_t * a_cert)
 }
 
 /**
- * @brief dap_cert_get_folder
- * @param a_folder_path
+ * @brief get certificate folder path
+ * usage example: dap_cert_get_folder(0) 
+ * @param a_n_folder_path 
+ * @return const char* 
  */
 const char* dap_cert_get_folder(int a_n_folder_path)
 {
@@ -511,8 +533,9 @@ const char* dap_cert_get_folder(int a_n_folder_path)
 
 
 /**
- * @brief dap_cert_add_folder
- * @param a_folder_path
+ * @brief load certificates from specified folder
+ * 
+ * @param a_folder_path const char *
  */
 void dap_cert_add_folder(const char *a_folder_path)
 {
@@ -551,6 +574,15 @@ void dap_cert_add_folder(const char *a_folder_path)
         log_it(L_WARNING, "Can't add folder %s to cert manager",a_folder_path);
 }
 
+/**
+ * @brief 
+ * 
+ * @param a_key const char *
+ * @param a_type dap_cert_metadata_type_t
+ * @param a_value void *
+ * @param a_value_size size_t
+ * @return dap_cert_metadata_t* 
+ */
 dap_cert_metadata_t *dap_cert_new_meta(const char *a_key, dap_cert_metadata_type_t a_type, void *a_value, size_t a_value_size)
 {
     if (!a_key || a_type > DAP_CERT_META_CUSTOM || (!a_value && a_value_size)) {
@@ -568,12 +600,13 @@ dap_cert_metadata_t *dap_cert_new_meta(const char *a_key, dap_cert_metadata_type
 }
 
 /**
- * @brief dap_cert_add_meta Add metadata to certificate
- * @param a_cert
- * @param a_key
- * @param a_type
- * @param a_value
- * @param a_value_size
+ * @brief Add metadata to certificate
+ * action for command "cellframe-node cert add_metadata <cert name> <key:type:length:value>"
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_key const char * key
+ * @param a_type dap_cert_metadata_type_t type
+ * @param a_value void * value
+ * @param a_value_size size_t length
  */
 void dap_cert_add_meta(dap_cert_t *a_cert, const char *a_key, dap_cert_metadata_type_t a_type, void *a_value, size_t a_value_size)
 {
@@ -588,6 +621,15 @@ void dap_cert_add_meta(dap_cert_t *a_cert, const char *a_key, dap_cert_metadata_
     }
 }
 
+/**
+ * @brief Add metadata to certificate with additional value modification
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_key const char * key
+ * @param a_type dap_cert_metadata_type_t type
+ * @param a_value void * value
+ * @param a_value_size size_t length
+ */
 void dap_cert_add_meta_scalar(dap_cert_t *a_cert, const char *a_key, dap_cert_metadata_type_t a_type, uint64_t a_value, size_t a_value_size)
 {
     void *l_value;
@@ -627,15 +669,24 @@ void dap_cert_add_meta_scalar(dap_cert_t *a_cert, const char *a_key, dap_cert_me
 }
 
 /**
- * @brief dap_cert_get_meta
- * @param a_cert
- * @param a_field
+ * @brief get specified metadata from certificate
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @return dap_cert_metadata_t* 
  */
 dap_cert_metadata_t *dap_cert_get_meta(dap_cert_t *a_cert, const char *a_field)
 {
     return dap_binary_tree_search(a_cert->metadata, a_field);
 }
 
+/**
+ * @brief get specified metadata from certificate in string (DAP_CERT_META_STRING) format
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @return char* 
+ */
 char *dap_cert_get_meta_string(dap_cert_t *a_cert, const char *a_field)
 {
     dap_cert_metadata_t *l_meta = dap_cert_get_meta(a_cert, a_field);
@@ -649,6 +700,14 @@ char *dap_cert_get_meta_string(dap_cert_t *a_cert, const char *a_field)
     return strndup((char *)&l_meta->value[0], l_meta->length);
 }
 
+/**
+ * @brief get metadata from certificate with boolean (DAP_CERT_META_BOOL) type
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @return true 
+ * @return false 
+ */
 bool dap_cert_get_meta_bool(dap_cert_t *a_cert, const char *a_field)
 {
     dap_cert_metadata_t *l_meta = dap_cert_get_meta(a_cert, a_field);
@@ -665,6 +724,13 @@ bool dap_cert_get_meta_bool(dap_cert_t *a_cert, const char *a_field)
     return *(bool *)&l_meta->value[0];
 }
 
+/**
+ * @brief get metadata from certificate with int (DAP_CERT_META_INT) type
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @return int 
+ */
 int dap_cert_get_meta_int(dap_cert_t *a_cert, const char *a_field)
 {
     dap_cert_metadata_t *l_meta = dap_cert_get_meta(a_cert, a_field);
@@ -681,6 +747,13 @@ int dap_cert_get_meta_int(dap_cert_t *a_cert, const char *a_field)
     return *(int *)&l_meta->value[0];
 }
 
+/**
+ * @brief get metadata from certificate with datetime (DAP_CERT_META_DATETIME) type
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @return time_t 
+ */
 time_t dap_cert_get_meta_time(dap_cert_t *a_cert, const char *a_field)
 {
     dap_cert_metadata_t *l_meta = dap_cert_get_meta(a_cert, a_field);
@@ -697,6 +770,13 @@ time_t dap_cert_get_meta_time(dap_cert_t *a_cert, const char *a_field)
     return *(time_t *)&l_meta->value[0];
 }
 
+/**
+ * @brief get metadata from certificate with datetime (DAP_CERT_META_DATETIME_PERIOD) type
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @return time_t 
+ */
 time_t dap_cert_get_meta_period(dap_cert_t *a_cert, const char *a_field)
 {
     dap_cert_metadata_t *l_meta = dap_cert_get_meta(a_cert, a_field);
@@ -713,6 +793,13 @@ time_t dap_cert_get_meta_period(dap_cert_t *a_cert, const char *a_field)
     return *(time_t *)&l_meta->value[0];
 }
 
+/**
+ * @brief get metadata from certificate with dap_sign_t (DAP_CERT_META_SIGN) type
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @return dap_sign_t* 
+ */
 dap_sign_t *dap_cert_get_meta_sign(dap_cert_t *a_cert, const char *a_field)
 {
     dap_cert_metadata_t *l_meta = dap_cert_get_meta(a_cert, a_field);
@@ -730,6 +817,14 @@ dap_sign_t *dap_cert_get_meta_sign(dap_cert_t *a_cert, const char *a_field)
     return l_ret;
 }
 
+/**
+ * @brief get metadata from certificate with custom (DAP_CERT_META_CUSTOM) type
+ * 
+ * @param a_cert dap_cert_t * certificate object
+ * @param a_field const char * field, which will be gotten from metadata
+ * @param a_meta_size_out size_t size of recieved data
+ * @return void* 
+ */
 void *dap_cert_get_meta_custom(dap_cert_t *a_cert, const char *a_field, size_t *a_meta_size_out)
 {
     dap_cert_metadata_t *l_meta = dap_cert_get_meta(a_cert, a_field);
@@ -748,8 +843,9 @@ void *dap_cert_get_meta_custom(dap_cert_t *a_cert, const char *a_field, size_t *
 
 /**
  * @brief dap_cert_deinit
+ * empty function
  */
 void dap_cert_deinit()
 {
 
-}
+}
\ No newline at end of file
diff --git a/dap-sdk/crypto/src/dap_sign.c b/dap-sdk/crypto/src/dap_sign.c
index dd1625e88f0215082e14f7330ec070a28b8e8b66..2582d4b1c3a29452a9c377a8c96ef986ae510074 100755
--- a/dap-sdk/crypto/src/dap_sign.c
+++ b/dap-sdk/crypto/src/dap_sign.c
@@ -38,7 +38,13 @@
 //static dap_sign_t * s_sign_null = NULL;
 static bliss_signature_t s_sign_bliss_null = {0};
 
-// calc signature size
+/**
+ * @brief get signature size (different for specific crypto algorithm)
+ * 
+ * @param a_key dap_enc_key_t * encryption key object
+ * @param a_output_wish_size size_t output size
+ * @return size_t 
+ */
 size_t dap_sign_create_output_unserialized_calc_size(dap_enc_key_t * a_key, size_t a_output_wish_size )
 {
     (void)a_output_wish_size;
@@ -60,8 +66,8 @@ size_t dap_sign_create_output_unserialized_calc_size(dap_enc_key_t * a_key, size
 
 
 /**
- * @brief dap_sign_type_from_key_type
- * @param a_key_type
+ * @brief get sign type (dap_sign_type_t) type from key type (dap_enc_key_type_t)
+ * @param a_key_type dap_enc_key_type_t key type
  * @return
  */
 dap_sign_type_t dap_sign_type_from_key_type( dap_enc_key_type_t a_key_type)
@@ -79,9 +85,9 @@ dap_sign_type_t dap_sign_type_from_key_type( dap_enc_key_type_t a_key_type)
 }
 
 /**
- * @brief dap_sign_type_to_key_type
- * @param a_chain_sign_type
- * @return
+ * @brief convert chain sign type (dap_sign_type_t) to encryption key type (dap_enc_key_type_t)
+ * @param a_chain_sign_type dap_enc_key_type_t signature type
+ * @return dap_enc_key_type_t
  */
 dap_enc_key_type_t  dap_sign_type_to_key_type(dap_sign_type_t  a_chain_sign_type)
 {
@@ -97,9 +103,10 @@ dap_enc_key_type_t  dap_sign_type_to_key_type(dap_sign_type_t  a_chain_sign_type
 
 
 /**
- * @brief dap_sign_type_to_str
- * @param a_chain_sign_type
- * @return
+ * @brief convert sign type (dap_sign_type_t) to string format
+ * [sig_bliss,sig_tesla,sig_picnic,sig_dil,sig_multi2,sig_multi]
+ * @param a_chain_sign_type sign type dap_sign_type_t
+ * @return const char* 
  */
 const char * dap_sign_type_to_str(dap_sign_type_t a_chain_sign_type)
 {
@@ -116,9 +123,10 @@ const char * dap_sign_type_to_str(dap_sign_type_t a_chain_sign_type)
 }
 
 /**
- * @brief dap_pkey_type_from_sign
- * @param a_pkey_type
- * @return
+ * @brief convert public key type (dap_pkey_type_t) to dap_sign_type_t type
+ * 
+ * @param a_pkey_type dap_pkey_type_t key type
+ * @return dap_sign_type_t 
  */
 dap_sign_type_t dap_pkey_type_from_sign( dap_pkey_type_t a_pkey_type)
 {
@@ -136,9 +144,10 @@ dap_sign_type_t dap_pkey_type_from_sign( dap_pkey_type_t a_pkey_type)
 
 
 /**
- * @brief dap_sign_type_from_str
- * @param a_type_str
- * @return
+ * @brief convert string to dap_sign_type_t type
+ * 
+ * @param a_type_str const char * algorithm type [sig_bliss,sig_tesla,sig_picnic,sig_dil,sig_multi2,sig_multi]
+ * @return dap_sign_type_t 
  */
 dap_sign_type_t dap_sign_type_from_str(const char * a_type_str)
 {
@@ -162,12 +171,14 @@ dap_sign_type_t dap_sign_type_from_str(const char * a_type_str)
 }
 
 /**
- * @brief dap_sign_create_output
- * @param a_key
- * @param a_data
- * @param a_data_size
- * @param a_output [in/out]
- * @return
+ * @brief encrypt data
+ * call a_key->enc_na or dap_enc_sig_bliss_get_sign
+ * @param a_key dap_enc_key_t key object
+ * @param a_data const void * data
+ * @param a_data_size const size_t size of data
+ * @param a_output void * output buffer
+ * @param a_output_size size_t size of output buffer
+ * @return int 
  */
 static int dap_sign_create_output(dap_enc_key_t *a_key, const void * a_data, const size_t a_data_size,
         void * a_output, size_t *a_output_size)
@@ -194,12 +205,13 @@ static int dap_sign_create_output(dap_enc_key_t *a_key, const void * a_data, con
 }
 
 /**
- * @brief dap_sign_create
- * @param a_key
- * @param a_data
- * @param a_data_size
- * @param a_output_wish_size
- * @return
+ * @brief sign data with specified key
+ * 
+ * @param a_key dap_enc_key_t key object
+ * @param a_data const void * buffer with data
+ * @param a_data_size const size_t buffer size
+ * @param a_output_wish_size size_t output buffer size
+ * @return dap_sign_t* 
  */
 dap_sign_t * dap_sign_create(dap_enc_key_t *a_key, const void * a_data,
         const size_t a_data_size, size_t a_output_wish_size)
@@ -243,14 +255,16 @@ dap_sign_t * dap_sign_create(dap_enc_key_t *a_key, const void * a_data,
     }
     return NULL;
 }
+
 /**
- * @brief dap_sign_pack
- * @param a_key
- * @param a_sign_ser
- * @param a_sign_ser_size
- * @param a_pkey
- * @param a_pub_key_size
- * @return dap_sign_t*
+ * @brief create signed object header (dap_sign_t) from variables
+ * 
+ * @param a_key dap_enc_key_t key object
+ * @param a_sign_ser signed data buffer
+ * @param a_sign_ser_size buffer size
+ * @param a_pkey public key
+ * @param a_pub_key_size pulic key size
+ * @return dap_sign_t* 
  */
 dap_sign_t * dap_sign_pack(dap_enc_key_t *a_key, const void * a_sign_ser, const size_t a_sign_ser_size, const void * a_pkey, const size_t a_pub_key_size)
 {
@@ -266,10 +280,11 @@ dap_sign_t * dap_sign_pack(dap_enc_key_t *a_key, const void * a_sign_ser, const
 }
 
 /**
- * @brief dap_sign_get_sign
- * @param a_sign
- * @param a_sign_out
- * @return
+ * @brief 
+ * get a_sign->pkey_n_sign + a_sign->header.sign_pkey_size
+ * @param a_sign dap_sign_t object (header + raw signature data)
+ * @param a_sign_out  a_sign->header.sign_size
+ * @return uint8_t* 
  */
 uint8_t* dap_sign_get_sign(dap_sign_t *a_sign, size_t *a_sign_out)
 {
@@ -281,10 +296,11 @@ uint8_t* dap_sign_get_sign(dap_sign_t *a_sign, size_t *a_sign_out)
 }
 
 /**
- * @brief dap_sign_get_pkey
- * @param a_sign
- * @param a_pub_key_out
- * @return
+ * @brief get a_sign->pkey_n_sign and a_sign->header.sign_pkey_size (optionally)
+ * 
+ * @param a_sign dap_sign_t sign object
+ * @param a_pub_key_out [option] output pointer to a_sign->header.sign_pkey_size
+ * @return uint8_t* 
  */
 uint8_t* dap_sign_get_pkey(dap_sign_t *a_sign, size_t *a_pub_key_out)
 {
@@ -296,10 +312,12 @@ uint8_t* dap_sign_get_pkey(dap_sign_t *a_sign, size_t *a_pub_key_out)
 }
 
 /**
- * @brief dap_sign_get_pkey_hash
- * @param a_sign
- * @param a_sign_hash
- * @return
+ * @brief get SHA3 hash of buffer (a_sign), storing in output buffer a_sign_hash
+ * 
+ * @param a_sign input buffer
+ * @param a_sign_hash output buffer
+ * @return true 
+ * @return false 
  */
 bool dap_sign_get_pkey_hash(dap_sign_t *a_sign, dap_chain_hash_fast_t * a_sign_hash)
 {
@@ -314,7 +332,14 @@ bool dap_sign_get_pkey_hash(dap_sign_t *a_sign, dap_chain_hash_fast_t * a_sign_h
     return dap_hash_fast( a_sign->pkey_n_sign,a_sign->header.sign_pkey_size,a_sign_hash );
 }
 
-
+/**
+ * @brief verify, if a_sign->header.sign_pkey_size and a_sign->header.sign_size bigger, then a_max_key_size
+ * 
+ * @param a_sign signed data object 
+ * @param a_max_key_size max size of key
+ * @return true 
+ * @return false 
+ */
 bool dap_sign_verify_size(dap_sign_t *a_sign, size_t a_max_key_size)
 {
     if (a_sign->header.sign_pkey_size > a_max_key_size)
@@ -325,9 +350,10 @@ bool dap_sign_verify_size(dap_sign_t *a_sign, size_t a_max_key_size)
 }
 
 /**
- * @brief dap_sign_to_enc_key
- * @param a_chain_sign
- * @return
+ * @brief get deserealized pub key from dap_sign_t 
+ * 
+ * @param a_chain_sign dap_sign_t object
+ * @return dap_enc_key_t* 
  */
 dap_enc_key_t *dap_sign_to_enc_key(dap_sign_t * a_chain_sign)
 {
@@ -343,10 +369,10 @@ dap_enc_key_t *dap_sign_to_enc_key(dap_sign_t * a_chain_sign)
 }
 
 /**
- * @brief dap_sign_verify
- * @param a_chain_sign
- * @param a_data
- * @param a_data_size
+ * @brief dap_sign_verify data signature
+ * @param a_chain_sign dap_sign_t a_chain_sign object
+ * @param a_data const void * buffer with data
+ * @param a_data_size const size_t  buffer size
  * @return 1 valid signature, 0 invalid signature, -1 unsupported sign type
  */
 int dap_sign_verify(dap_sign_t * a_chain_sign, const void * a_data, const size_t a_data_size)
@@ -403,8 +429,12 @@ int dap_sign_verify(dap_sign_t * a_chain_sign, const void * a_data, const size_t
     return l_ret;
 }
 
+
 /**
- * Get size of struct dap_sign_t
+ * @brief Get size of struct dap_sign_t
+ * 
+ * @param a_chain_sign dap_sign_t object
+ * @return size_t 
  */
 size_t dap_sign_get_size(dap_sign_t * a_chain_sign)
 {