diff --git a/src/cert.rs b/src/cert.rs
index 6b6f7cf..2f416e6 100644
--- a/src/cert.rs
+++ b/src/cert.rs
@@ -15,10 +15,10 @@ pub struct Cert {
 pub fn load_certificate(cert_fn: &str, key_fn: &str) -> Result<(Certificate, String), String> {
     let cert_pem = fs::read_to_string(cert_fn)
         .map_err(|e| format!("Read file: {} failed: {}", cert_fn, e))?;
-    
+
     let key_pem = fs::read_to_string(key_fn)
         .map_err(|e| format!("Read file: {} failed: {}", key_fn, e))?;
-    let key_pem = resolve_ec_pkcs8(&key_pem);
+    let key_pem = resolve_ecc_pkcs8(&key_pem);
     let key_pair = KeyPair::from_pem(&key_pem)
         .map_err(|e| format!("Parse key: {} failed: {}", key_fn, e))?;
 
@@ -56,7 +56,7 @@ macro_rules! ecc_private_key_convert {
     }};
 }
 
-fn resolve_ec_pkcs8(pem: &str) -> String {
+fn resolve_ecc_pkcs8(pem: &str) -> String {
     // KeyPair only support PKCS#8 private key with public key, though public key is optional
     ecc_private_key_convert!(p256, pem);
     ecc_private_key_convert!(p384, pem);
@@ -66,7 +66,7 @@ fn resolve_ec_pkcs8(pem: &str) -> String {
 
 fn build_certificate(domain: &str) -> Result<Certificate, String> {
     let mut params = CertificateParams::new(vec![domain.into()]);
-    let (start, end) = validity_period()?;
+    let (start, end) = build_validity_period()?;
     params.distinguished_name.push(DnType::CommonName, domain);
     params.use_authority_key_identifier_extension = true;
     params.key_usages.push(KeyUsagePurpose::DigitalSignature);
@@ -78,10 +78,10 @@ fn build_certificate(domain: &str) -> Result<Certificate, String> {
     Certificate::from_params(params).map_err(|e| format!("New cert failed: {}", e))
 }
 
-fn validity_period() -> Result<(OffsetDateTime, OffsetDateTime), String> {
+fn build_validity_period() -> Result<(OffsetDateTime, OffsetDateTime), String> {
     let start = OffsetDateTime::now_utc().checked_sub(Duration::hours(1))
         .ok_or_else::<String, _>(|| "Generate start datetime failed.".into())?;
     let end = OffsetDateTime::now_utc().checked_add(Duration::days(90))
-        .ok_or_else::<String, _>(|| "Generate start datetime failed.".into())?;
+        .ok_or_else::<String, _>(|| "Generate end datetime failed.".into())?;
     Ok((start, end))
 }