diff --git a/acme_common/src/crypto/jws_signature_algorithm.rs b/acme_common/src/crypto/jws_signature_algorithm.rs
index 8a8d27d..b06beda 100644
--- a/acme_common/src/crypto/jws_signature_algorithm.rs
+++ b/acme_common/src/crypto/jws_signature_algorithm.rs
@@ -4,6 +4,9 @@ use std::str::FromStr;
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum JwsSignatureAlgorithm {
+    Hs256,
+    Hs384,
+    Hs512,
     Rs256,
     Es256,
     Es384,
@@ -18,6 +21,9 @@ impl FromStr for JwsSignatureAlgorithm {
 
     fn from_str(s: &str) -> Result<Self, Error> {
         match s.to_lowercase().as_str() {
+            "hs256" => Ok(JwsSignatureAlgorithm::Hs256),
+            "hs384" => Ok(JwsSignatureAlgorithm::Hs384),
+            "hs512" => Ok(JwsSignatureAlgorithm::Hs512),
             "rs256" => Ok(JwsSignatureAlgorithm::Rs256),
             "es256" => Ok(JwsSignatureAlgorithm::Es256),
             "es384" => Ok(JwsSignatureAlgorithm::Es384),
@@ -33,6 +39,9 @@ impl FromStr for JwsSignatureAlgorithm {
 impl fmt::Display for JwsSignatureAlgorithm {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let s = match self {
+            JwsSignatureAlgorithm::Hs256 => "HS256",
+            JwsSignatureAlgorithm::Hs384 => "HS384",
+            JwsSignatureAlgorithm::Hs512 => "HS512",
             JwsSignatureAlgorithm::Rs256 => "RS256",
             JwsSignatureAlgorithm::Es256 => "ES256",
             JwsSignatureAlgorithm::Es384 => "ES384",
diff --git a/acme_common/src/crypto/openssl_keys.rs b/acme_common/src/crypto/openssl_keys.rs
index 591fa40..f6aae3f 100644
--- a/acme_common/src/crypto/openssl_keys.rs
+++ b/acme_common/src/crypto/openssl_keys.rs
@@ -85,6 +85,13 @@ impl KeyPair {
     pub fn sign(&self, alg: &JwsSignatureAlgorithm, data: &[u8]) -> Result<Vec<u8>, Error> {
         let _ = self.key_type.check_alg_compatibility(alg)?;
         match alg {
+            JwsSignatureAlgorithm::Hs256
+            | JwsSignatureAlgorithm::Hs384
+            | JwsSignatureAlgorithm::Hs512 => Err(format!(
+                "{} key pair cannot be used for the {} signature algorithm",
+                self.key_type, alg
+            )
+            .into()),
             JwsSignatureAlgorithm::Rs256 => self.sign_rsa(&MessageDigest::sha256(), data),
             JwsSignatureAlgorithm::Es256 => self.sign_ecdsa(&HashFunction::Sha256, data),
             JwsSignatureAlgorithm::Es384 => self.sign_ecdsa(&HashFunction::Sha384, data),
diff --git a/acmed/src/jws.rs b/acmed/src/jws.rs
index 62d366f..b6bf0b9 100644
--- a/acmed/src/jws.rs
+++ b/acmed/src/jws.rs
@@ -1,5 +1,5 @@
 use acme_common::b64_encode;
-use acme_common::crypto::{JwsSignatureAlgorithm, KeyPair};
+use acme_common::crypto::{HashFunction, JwsSignatureAlgorithm, KeyPair};
 use acme_common::error::Error;
 use serde::Serialize;
 use serde_json::value::Value;
@@ -26,6 +26,13 @@ struct JwsProtectedHeaderJwk {
     url: String,
 }
 
+#[derive(Serialize)]
+struct JwsProtectedHeaderKidNoNonce {
+    alg: String,
+    kid: String,
+    url: String,
+}
+
 #[derive(Serialize)]
 struct JwsProtectedHeaderKid {
     alg: String,
@@ -104,6 +111,41 @@ pub fn encode_kid(
     get_data(key_pair, sign_alg, &protected, payload)
 }
 
+pub fn encode_kid_mac(
+    key: &[u8],
+    sign_alg: &JwsSignatureAlgorithm,
+    key_id: &str,
+    payload: &[u8],
+    url: &str,
+) -> Result<String, Error> {
+    let protected = JwsProtectedHeaderKidNoNonce {
+        alg: sign_alg.to_string(),
+        kid: key_id.to_string(),
+        url: url.into(),
+    };
+    let protected = serde_json::to_string(&protected)?;
+    let protected = b64_encode(&protected);
+    let payload = b64_encode(payload);
+    let signing_input = format!("{}.{}", protected, payload);
+    let hash_func = match sign_alg {
+        JwsSignatureAlgorithm::Hs256 => HashFunction::Sha256,
+        JwsSignatureAlgorithm::Hs384 => HashFunction::Sha384,
+        JwsSignatureAlgorithm::Hs512 => HashFunction::Sha512,
+        _ => {
+            return Err(format!("{}: not a HMAC-based signature algorithm", sign_alg).into());
+        }
+    };
+    let signature = hash_func.hmac(key, signing_input.as_bytes())?;
+    let signature = b64_encode(&signature);
+    let data = JwsData {
+        protected,
+        payload,
+        signature,
+    };
+    let str_data = serde_json::to_string(&data)?;
+    Ok(str_data)
+}
+
 #[cfg(test)]
 mod tests {
     use super::{encode_jwk, encode_kid};