diff --git a/src/argsutil.rs b/src/argsutil.rs
index d78c231..39b00bb 100644
--- a/src/argsutil.rs
+++ b/src/argsutil.rs
@@ -5,7 +5,7 @@ use std::io::Read;
 use clap::ArgMatches;
 use rust_util::XResult;
 
-use crate::digest::{sha256, sha256_bytes};
+use crate::digestutil::{sha256, sha256_bytes};
 
 
 pub fn get_sha256_digest_or_hash(sub_arg_matches: &ArgMatches) -> XResult<Vec<u8>> {
diff --git a/src/cmd_file_sign.rs b/src/cmd_file_sign.rs
index 1212230..4b21ada 100644
--- a/src/cmd_file_sign.rs
+++ b/src/cmd_file_sign.rs
@@ -11,7 +11,7 @@ use yubikey::{Key, YubiKey};
 use yubikey::piv::{sign_data, SlotId};
 
 use crate::{argsutil, cmdutil, pinutil, pivutil};
-use crate::digest::sha256_bytes;
+use crate::digestutil::sha256_bytes;
 use crate::signfile::{CERTIFICATES_SEARCH_URL, HASH_ALGORITHM_SHA256, SIGNATURE_ALGORITHM_SHA256_WITH_ECDSA, SignFileRequest, SIMPLE_SIG_SCHEMA, SimpleSignFile, SimpleSignFileSignature};
 use crate::util::base64_encode;
 
diff --git a/src/cmd_file_verify.rs b/src/cmd_file_verify.rs
index 747f10e..0fdef65 100644
--- a/src/cmd_file_verify.rs
+++ b/src/cmd_file_verify.rs
@@ -11,7 +11,7 @@ use x509_parser::public_key::PublicKey;
 use x509_parser::time::ASN1Time;
 
 use crate::argsutil;
-use crate::digest::sha256_bytes;
+use crate::digestutil::sha256_bytes;
 use crate::signfile::{SignFileRequest, SIMPLE_SIG_SCHEMA, SimpleSignFile};
 use crate::util::base64_decode;
 
diff --git a/src/cmd_pgp_card_sign.rs b/src/cmd_pgp_card_sign.rs
index b816f31..2754711 100644
--- a/src/cmd_pgp_card_sign.rs
+++ b/src/cmd_pgp_card_sign.rs
@@ -114,7 +114,7 @@ impl Command for CommandImpl {
 
         if let Some(sha256) = sha256 {
             let sha256_hex = opt_result!(hex::decode(sha256.trim()), "Decode sha256 failed: {}");
-            let sha256_hex = crate::digest::copy_sha256(&sha256_hex)?;
+            let sha256_hex = crate::digestutil::copy_sha256(&sha256_hex)?;
             opt_result!(trans.verify_pw1_sign(pin.as_ref()), "User sign pin verify failed: {}");
             success!("User sign pin verify success!");
             let sig = match algo {
@@ -133,7 +133,7 @@ impl Command for CommandImpl {
         }
         if let Some(sha384) = sha384 {
             let sha384_hex = opt_result!(hex::decode(sha384.trim()), "Decode sha384 failed: {}");
-            let sha384_hex = crate::digest::copy_sha384(&sha384_hex)?;
+            let sha384_hex = crate::digestutil::copy_sha384(&sha384_hex)?;
             opt_result!(trans.verify_pw1_sign(pin.as_ref()), "User sign pin verify failed: {}");
             success!("User sign pin verify success!");
             let sig = match algo {
@@ -152,7 +152,7 @@ impl Command for CommandImpl {
         }
         if let Some(sha512) = sha512 {
             let sha512_hex = opt_result!(hex::decode(sha512.trim()), "Decode sha512 failed: {}");
-            let sha512_hex = crate::digest::copy_sha512(&sha512_hex)?;
+            let sha512_hex = crate::digestutil::copy_sha512(&sha512_hex)?;
             opt_result!(trans.verify_pw1_sign(pin.as_ref()), "User sign pin verify failed: {}");
             success!("User sign pin verify success!");
             let sig = match algo {
diff --git a/src/cmd_rsa_encrypt.rs b/src/cmd_rsa_encrypt.rs
index 6784a66..3156793 100644
--- a/src/cmd_rsa_encrypt.rs
+++ b/src/cmd_rsa_encrypt.rs
@@ -7,7 +7,7 @@ use openssl::pkey::PKey;
 use openssl::rsa::Rsa;
 use rust_util::util_clap::{Command, CommandError};
 use crate::{cmdutil, util};
-use crate::digest::sha256_bytes;
+use crate::digestutil::sha256_bytes;
 
 pub struct CommandImpl;
 
diff --git a/src/cmd_rsa_verify.rs b/src/cmd_rsa_verify.rs
index 815e1d2..36f2d04 100644
--- a/src/cmd_rsa_verify.rs
+++ b/src/cmd_rsa_verify.rs
@@ -12,7 +12,7 @@ use rust_util::util_clap::{Command, CommandError};
 use rust_util::util_msg::MessageType;
 use rust_util::{util_msg, XResult};
 
-use crate::digest::sha256_bytes;
+use crate::digestutil::sha256_bytes;
 
 pub struct CommandImpl;
 
diff --git a/src/cmd_sign_jwt.rs b/src/cmd_sign_jwt.rs
index 14bc38b..be0083a 100644
--- a/src/cmd_sign_jwt.rs
+++ b/src/cmd_sign_jwt.rs
@@ -11,7 +11,7 @@ use yubikey::piv::{sign_data, AlgorithmId, SlotId};
 use yubikey::{Certificate, YubiKey};
 
 use crate::ecdsautil::parse_ecdsa_to_rs;
-use crate::{cmdutil, digest, pivutil, rsautil, util};
+use crate::{cmdutil, digestutil, pivutil, rsautil, util};
 
 const SEPARATOR: &str = ".";
 
@@ -111,10 +111,10 @@ fn sign_jwt(
 
     let raw_in = match jwt_algorithm {
         AlgorithmType::Rs256 => {
-            rsautil::pkcs15_sha256_rsa_2048_padding_for_sign(&digest::sha256_bytes(&tobe_signed))
+            rsautil::pkcs15_sha256_rsa_2048_padding_for_sign(&digestutil::sha256_bytes(&tobe_signed))
         }
-        AlgorithmType::Es256 => digest::sha256_bytes(&tobe_signed),
-        AlgorithmType::Es384 => digest::sha384_bytes(&tobe_signed),
+        AlgorithmType::Es256 => digestutil::sha256_bytes(&tobe_signed),
+        AlgorithmType::Es384 => digestutil::sha384_bytes(&tobe_signed),
         _ => return simple_error!("SHOULD NOT HAPPEN: {:?}", jwt_algorithm),
     };
 
diff --git a/src/cmd_sign_jwt_soft.rs b/src/cmd_sign_jwt_soft.rs
index 32e6fd5..7440844 100644
--- a/src/cmd_sign_jwt_soft.rs
+++ b/src/cmd_sign_jwt_soft.rs
@@ -6,7 +6,7 @@ use serde_json::{Map, Value};
 
 use crate::cmd_sign_jwt::{build_jwt_parts, merge_header_claims, merge_payload_claims, print_jwt_token};
 use crate::keychain::{KeychainKey, KeychainKeyValue};
-use crate::{cmd_sign_jwt, cmdutil, digest, ecdsautil, hmacutil, keychain, rsautil, util};
+use crate::{cmd_sign_jwt, cmdutil, digestutil, ecdsautil, hmacutil, keychain, rsautil, util};
 
 const SEPARATOR: &str = ".";
 
@@ -84,10 +84,10 @@ fn sign_jwt(
 
     let raw_in = match jwt_algorithm {
         AlgorithmType::Rs256 => {
-            rsautil::pkcs15_sha256_rsa_2048_padding_for_sign(&digest::sha256_bytes(&tobe_signed))
+            rsautil::pkcs15_sha256_rsa_2048_padding_for_sign(&digestutil::sha256_bytes(&tobe_signed))
         }
-        AlgorithmType::Es256 => digest::sha256_bytes(&tobe_signed),
-        AlgorithmType::Es384 => digest::sha384_bytes(&tobe_signed),
+        AlgorithmType::Es256 => digestutil::sha256_bytes(&tobe_signed),
+        AlgorithmType::Es384 => digestutil::sha384_bytes(&tobe_signed),
         _ => return simple_error!("SHOULD NOT HAPPEN: {:?}", jwt_algorithm),
     };
 
diff --git a/src/cmd_ssh_agent.rs b/src/cmd_ssh_agent.rs
index e0f823c..d427786 100644
--- a/src/cmd_ssh_agent.rs
+++ b/src/cmd_ssh_agent.rs
@@ -14,7 +14,7 @@ use ssh_agent::proto::{from_bytes, RsaPublicKey, signature, Signature, to_bytes}
 use ssh_agent::proto::message::{self, Message};
 use ssh_agent::proto::public_key::PublicKey;
 
-use crate::digest::{copy_sha256, copy_sha512};
+use crate::digestutil::{copy_sha256, copy_sha512};
 use crate::pinutil;
 use crate::sshutil::{generate_ssh_string, with_sign};
 
diff --git a/src/cmd_ssh_piv_cert.rs b/src/cmd_ssh_piv_cert.rs
index a0cb050..8281226 100644
--- a/src/cmd_ssh_piv_cert.rs
+++ b/src/cmd_ssh_piv_cert.rs
@@ -13,7 +13,7 @@ use std::time::SystemTime;
 use yubikey::piv::{sign_data, AlgorithmId, SlotId};
 use yubikey::{Key, YubiKey};
 
-use crate::digest::{sha256_bytes, sha384_bytes};
+use crate::digestutil::{sha256_bytes, sha384_bytes};
 use crate::pivutil::slot_equals;
 use crate::{cmdutil, pinutil, pivutil, util};
 
diff --git a/src/cmd_ssh_piv_sign.rs b/src/cmd_ssh_piv_sign.rs
index 3a3b69a..3ce5215 100644
--- a/src/cmd_ssh_piv_sign.rs
+++ b/src/cmd_ssh_piv_sign.rs
@@ -91,14 +91,14 @@ impl Command for CommandImpl {
         sign_message.write_string(namespace.as_bytes());
         sign_message.write_string("".as_bytes());
         sign_message.write_string("sha512".as_bytes());
-        let data_digest = crate::digest::sha512_bytes(&data);
+        let data_digest = crate::digestutil::sha512_bytes(&data);
         debugging!("Data digest: {} (sha512)", hex::encode(&data_digest));
         sign_message.write_string(&data_digest);
         debugging!("Singed message: {}", hex::encode(&sign_message));
         let tobe_signed_data = if ec_bit_len == 256 {
-            crate::digest::sha256_bytes(&sign_message)
+            crate::digestutil::sha256_bytes(&sign_message)
         } else {
-            crate::digest::sha384_bytes(&sign_message)
+            crate::digestutil::sha384_bytes(&sign_message)
         };
         debugging!("Digest of signed message: {}", hex::encode(&tobe_signed_data));
 
diff --git a/src/cmd_ssh_pub_key.rs b/src/cmd_ssh_pub_key.rs
index e91a075..490bd13 100644
--- a/src/cmd_ssh_pub_key.rs
+++ b/src/cmd_ssh_pub_key.rs
@@ -1,4 +1,4 @@
-use crate::digest::sha256_bytes;
+use crate::digestutil::sha256_bytes;
 use crate::pivutil::{get_algorithm_id_by_certificate, slot_equals, ToStr};
 use crate::sshutil::SshVecWriter;
 use crate::{cmdutil, pivutil, util};
diff --git a/src/cmd_u2f_register.rs b/src/cmd_u2f_register.rs
index 1bb3d39..5ca36c8 100644
--- a/src/cmd_u2f_register.rs
+++ b/src/cmd_u2f_register.rs
@@ -12,9 +12,9 @@ use rust_util::util_clap::{Command, CommandError};
 use x509_parser::certificate::X509Certificate;
 use x509_parser::prelude::FromDer;
 
-use crate::{cmdutil, digest, util};
-use crate::fido;
-use crate::fido::{U2fRegistrationData, U2fV2Challenge};
+use crate::{cmdutil, digestutil, util};
+use crate::fidoutil;
+use crate::fidoutil::{U2fRegistrationData, U2fV2Challenge};
 use crate::util::base64_encode;
 
 pub struct CommandImpl;
@@ -46,12 +46,12 @@ impl Command for CommandImpl {
         let u2fv2_challenge = U2fV2Challenge::new_challenge(challenge_hex, app_id, challenge_with_timestamp_prefix)?;
         let u2fv2_challenge_str = u2fv2_challenge.to_json();
 
-        let app_id_hash = digest::sha256(app_id);
-        let challenge_hash = digest::sha256(&u2fv2_challenge_str);
+        let app_id_hash = digestutil::sha256(app_id);
+        let challenge_hash = digestutil::sha256(&u2fv2_challenge_str);
 
         let flags = RegisterFlags::empty();
 
-        let status_tx = fido::start_status_updater();
+        let status_tx = fidoutil::start_status_updater();
 
         let (register_tx, register_rx) = channel();
         let callback = StateCallback::new(Box::new(move |rv| {
diff --git a/src/cmd_u2f_sign.rs b/src/cmd_u2f_sign.rs
index ab43eaf..7a3da6a 100644
--- a/src/cmd_u2f_sign.rs
+++ b/src/cmd_u2f_sign.rs
@@ -13,9 +13,9 @@ use openssl::pkey::PKey;
 use openssl::sign::Verifier;
 use rust_util::util_clap::{Command, CommandError};
 
-use crate::{cmdutil, digest, util};
-use crate::fido;
-use crate::fido::U2fV2Challenge;
+use crate::{cmdutil, digestutil, util};
+use crate::fidoutil;
+use crate::fidoutil::U2fV2Challenge;
 use crate::util::base64_encode;
 
 pub struct CommandImpl;
@@ -71,10 +71,10 @@ impl Command for CommandImpl {
         let u2fv2_challenge = U2fV2Challenge::new_challenge(challenge_hex, app_id, challenge_with_timestamp_prefix)?;
         let u2fv2_challenge_str = u2fv2_challenge.to_json();
 
-        let app_id_hash = digest::sha256(app_id);
-        let challenge_hash = digest::sha256(&u2fv2_challenge_str);
+        let app_id_hash = digestutil::sha256(app_id);
+        let challenge_hash = digestutil::sha256(&u2fv2_challenge_str);
 
-        let status_tx = fido::start_status_updater();
+        let status_tx = fidoutil::start_status_updater();
 
         information!("App id: {}, Start sign...", app_id);
         debugging!("Wait timeout: {} ms", timeout_ms);
diff --git a/src/digest.rs b/src/digestutil.rs
similarity index 100%
rename from src/digest.rs
rename to src/digestutil.rs
diff --git a/src/fido.rs b/src/fidoutil.rs
similarity index 100%
rename from src/fido.rs
rename to src/fidoutil.rs
diff --git a/src/hmacutil.rs b/src/hmacutil.rs
index df91ab6..3ba5606 100644
--- a/src/hmacutil.rs
+++ b/src/hmacutil.rs
@@ -8,7 +8,7 @@ use yubico_manager::config::{Config, Mode, Slot};
 use yubico_manager::hmacmode::HmacKey;
 use yubico_manager::sec::hmac_sha1;
 use yubico_manager::Yubico;
-use crate::digest::{copy_sha256, sha256_bytes};
+use crate::digestutil::{copy_sha256, sha256_bytes};
 use crate::util;
 use crate::util::{base64_decode, base64_encode};
 
@@ -129,10 +129,10 @@ pub fn output_hmac_result(sub_arg_matches: &ArgMatches, json_output: bool, chall
     let sha512_output = sub_arg_matches.is_present("sha512");
 
     let hex_string = hex::encode(result);
-    let hex_sha1 = iff!(sha1_output, Some(crate::digest::sha1_bytes(result)), None);
-    let hex_sha256 = iff!(sha256_output, Some(crate::digest::sha256_bytes(result)), None);
-    let hex_sha384 = iff!(sha384_output, Some(crate::digest::sha384_bytes(result)), None);
-    let hex_sha512 = iff!(sha512_output, Some(crate::digest::sha512_bytes(result)), None);
+    let hex_sha1 = iff!(sha1_output, Some(crate::digestutil::sha1_bytes(result)), None);
+    let hex_sha256 = iff!(sha256_output, Some(crate::digestutil::sha256_bytes(result)), None);
+    let hex_sha384 = iff!(sha384_output, Some(crate::digestutil::sha384_bytes(result)), None);
+    let hex_sha512 = iff!(sha512_output, Some(crate::digestutil::sha512_bytes(result)), None);
 
     if json_output {
         let mut json = BTreeMap::<&'_ str, String>::new();
diff --git a/src/main.rs b/src/main.rs
index fa1c2e8..9043896 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -55,10 +55,10 @@ mod cmd_parseecdsasignature;
 mod cmd_keypair_generate;
 mod cmd_keypair_keychain_import;
 mod cmd_keypair_keychain_export;
-mod digest;
+mod digestutil;
 mod ecdhutil;
 mod ecdsautil;
-mod fido;
+mod fidoutil;
 mod hmacutil;
 mod keyutil;
 mod pgpcardutil;
diff --git a/src/pkiutil.rs b/src/pkiutil.rs
index 72624a1..fb750a9 100644
--- a/src/pkiutil.rs
+++ b/src/pkiutil.rs
@@ -7,7 +7,7 @@ use rust_util::XResult;
 use sequoia_openpgp::crypto::mpi::PublicKey;
 use x509_parser::x509::AlgorithmIdentifier;
 
-use crate::digest::sha256_bytes;
+use crate::digestutil::sha256_bytes;
 
 #[derive(Clone, Copy, Debug)]
 pub enum PkiAlgorithm {