diff --git a/changes/ticket30642 b/changes/ticket30642
new file mode 100644
index 0000000000..13941b2ac5
--- /dev/null
+++ b/changes/ticket30642
@@ -0,0 +1,4 @@
+  o Minor features (ed25519, relay):
+    - Save a relay's base64-encoded ed25519 identity key to the data
+      directory in a file named fingerprint-ed25519. Closes ticket 30642.
+      Patch by Neel Chauhan.
diff --git a/src/app/main/main.c b/src/app/main/main.c
index 32c34ea821..e6fa789a7d 100644
--- a/src/app/main/main.c
+++ b/src/app/main/main.c
@@ -1053,12 +1053,14 @@ sandbox_init_filter(void)
 
     OPEN_DATADIR("approved-routers");
     OPEN_DATADIR_SUFFIX("fingerprint", ".tmp");
+    OPEN_DATADIR_SUFFIX("fingerprint-ed25519", ".tmp");
     OPEN_DATADIR_SUFFIX("hashed-fingerprint", ".tmp");
     OPEN_DATADIR_SUFFIX("router-stability", ".tmp");
 
     OPEN("/etc/resolv.conf");
 
     RENAME_SUFFIX("fingerprint", ".tmp");
+    RENAME_SUFFIX("fingerprint-ed25519", ".tmp");
     RENAME_KEYDIR_SUFFIX("secret_onion_key_ntor", ".tmp");
 
     RENAME_KEYDIR_SUFFIX("secret_id_key", ".tmp");
diff --git a/src/feature/relay/router.c b/src/feature/relay/router.c
index 1691ac5f48..dfe9c9a823 100644
--- a/src/feature/relay/router.c
+++ b/src/feature/relay/router.c
@@ -831,30 +831,37 @@ router_initialize_tls_context(void)
  * -1 if Tor should die,
  */
 STATIC int
-router_write_fingerprint(int hashed)
+router_write_fingerprint(int hashed, int ed25519_identity)
 {
   char *keydir = NULL, *cp = NULL;
   const char *fname = hashed ? "hashed-fingerprint" :
-                               "fingerprint";
+                      (ed25519_identity ? "fingerprint-ed25519" :
+                                          "fingerprint");
   char fingerprint[FINGERPRINT_LEN+1];
   const or_options_t *options = get_options();
   char *fingerprint_line = NULL;
   int result = -1;
 
   keydir = get_datadir_fname(fname);
-  log_info(LD_GENERAL,"Dumping %sfingerprint to \"%s\"...",
-           hashed ? "hashed " : "", keydir);
-  if (!hashed) {
-    if (crypto_pk_get_fingerprint(get_server_identity_key(),
-                                  fingerprint, 0) < 0) {
-      log_err(LD_GENERAL,"Error computing fingerprint");
-      goto done;
-    }
-  } else {
-    if (crypto_pk_get_hashed_fingerprint(get_server_identity_key(),
-                                         fingerprint) < 0) {
-      log_err(LD_GENERAL,"Error computing hashed fingerprint");
-      goto done;
+  log_info(LD_GENERAL,"Dumping %s%s to \"%s\"...", hashed ? "hashed " : "",
+           ed25519_identity ? "ed25519 identity" : "fingerprint", keydir);
+
+  if (ed25519_identity) { /* ed25519 identity */
+    digest256_to_base64(fingerprint, (const char *)
+                                     get_master_identity_key()->pubkey);
+  } else { /* RSA identity */
+    if (!hashed) {
+      if (crypto_pk_get_fingerprint(get_server_identity_key(),
+                                    fingerprint, 0) < 0) {
+        log_err(LD_GENERAL,"Error computing fingerprint");
+        goto done;
+      }
+    } else {
+      if (crypto_pk_get_hashed_fingerprint(get_server_identity_key(),
+                                           fingerprint) < 0) {
+        log_err(LD_GENERAL,"Error computing hashed fingerprint");
+        goto done;
+      }
     }
   }
 
@@ -865,15 +872,17 @@ router_write_fingerprint(int hashed)
   cp = read_file_to_str(keydir, RFTS_IGNORE_MISSING, NULL);
   if (!cp || strcmp(cp, fingerprint_line)) {
     if (write_str_to_file(keydir, fingerprint_line, 0)) {
-      log_err(LD_FS, "Error writing %sfingerprint line to file",
-              hashed ? "hashed " : "");
+      log_err(LD_FS, "Error writing %s%s line to file",
+              hashed ? "hashed " : "",
+              ed25519_identity ? "ed25519 identity" : "fingerprint");
       goto done;
     }
   }
 
-  log_notice(LD_GENERAL, "Your Tor %s identity key fingerprint is '%s %s'",
-             hashed ? "bridge's hashed" : "server's", options->Nickname,
-             fingerprint);
+  log_notice(LD_GENERAL, "Your Tor %s identity key %s fingerprint is '%s %s'",
+             hashed ? "bridge's hashed" : "server's",
+             ed25519_identity ? "ed25519" : "",
+             options->Nickname, fingerprint);
 
   result = 0;
  done:
@@ -1109,15 +1118,20 @@ init_keys(void)
     }
   }
 
-  /* 5. Dump fingerprint and possibly hashed fingerprint to files. */
-  if (router_write_fingerprint(0)) {
+  /* 5. Dump fingerprint, ed25519 identity and possibly hashed fingerprint
+   * to files. */
+  if (router_write_fingerprint(0, 0)) {
     log_err(LD_FS, "Error writing fingerprint to file");
     return -1;
   }
-  if (!public_server_mode(options) && router_write_fingerprint(1)) {
+  if (!public_server_mode(options) && router_write_fingerprint(1, 0)) {
     log_err(LD_FS, "Error writing hashed fingerprint to file");
     return -1;
   }
+  if (router_write_fingerprint(0, 1)) {
+    log_err(LD_FS, "Error writing ed25519 identity to file");
+    return -1;
+  }
 
   if (!authdir_mode(options))
     return 0;
diff --git a/src/feature/relay/router.h b/src/feature/relay/router.h
index 50790a73dd..b7d99a1016 100644
--- a/src/feature/relay/router.h
+++ b/src/feature/relay/router.h
@@ -124,7 +124,7 @@ void router_free_all(void);
 #ifdef ROUTER_PRIVATE
 /* Used only by router.c and the unit tests */
 STATIC void get_platform_str(char *platform, size_t len);
-STATIC int router_write_fingerprint(int hashed);
+STATIC int router_write_fingerprint(int hashed, int ed25519_identity);
 STATIC smartlist_t *get_my_declared_family(const or_options_t *options);
 
 #ifdef TOR_UNIT_TESTS
diff --git a/src/test/test_routerkeys.c b/src/test/test_routerkeys.c
index fc437dccc0..bafc886bc6 100644
--- a/src/test/test_routerkeys.c
+++ b/src/test/test_routerkeys.c
@@ -51,7 +51,7 @@ test_routerkeys_write_fingerprint(void *arg)
   tt_int_op(crypto_pk_cmp_keys(get_server_identity_key(),key),OP_EQ,0);
 
   /* Write fingerprint file */
-  tt_int_op(0, OP_EQ, router_write_fingerprint(0));
+  tt_int_op(0, OP_EQ, router_write_fingerprint(0, 0));
   cp = read_file_to_str(get_fname("write_fingerprint/fingerprint"),
                         0, NULL);
   crypto_pk_get_fingerprint(key, fp, 0);
@@ -61,7 +61,7 @@ test_routerkeys_write_fingerprint(void *arg)
   tor_free(cp2);
 
   /* Write hashed-fingerprint file */
-  tt_int_op(0, OP_EQ, router_write_fingerprint(1));
+  tt_int_op(0, OP_EQ, router_write_fingerprint(1, 0));
   cp = read_file_to_str(get_fname("write_fingerprint/hashed-fingerprint"),
                         0, NULL);
   crypto_pk_get_hashed_fingerprint(key, fp);
@@ -73,7 +73,7 @@ test_routerkeys_write_fingerprint(void *arg)
   /* Replace outdated file */
   write_str_to_file(get_fname("write_fingerprint/hashed-fingerprint"),
                     "junk goes here", 0);
-  tt_int_op(0, OP_EQ, router_write_fingerprint(1));
+  tt_int_op(0, OP_EQ, router_write_fingerprint(1, 0));
   cp = read_file_to_str(get_fname("write_fingerprint/hashed-fingerprint"),
                         0, NULL);
   crypto_pk_get_hashed_fingerprint(key, fp);
@@ -89,6 +89,52 @@ test_routerkeys_write_fingerprint(void *arg)
   tor_free(cp2);
 }
 
+static void
+test_routerkeys_write_ed25519_identity(void *arg)
+{
+  crypto_pk_t *key = pk_generate(2);
+  or_options_t *options = get_options_mutable();
+  time_t now = time(NULL);
+  const char *ddir = get_fname("write_fingerprint");
+  char *cp = NULL, *cp2 = NULL;
+  char ed25519_id[BASE64_DIGEST256_LEN + 1];
+
+  (void) arg;
+
+  tt_assert(key);
+
+  options->ORPort_set = 1; /* So that we can get the server ID key */
+  tor_free(options->DataDirectory);
+  options->DataDirectory = tor_strdup(ddir);
+  options->Nickname = tor_strdup("haflinger");
+  set_server_identity_key(key);
+  set_client_identity_key(crypto_pk_dup_key(key));
+
+  load_ed_keys(options, now);
+  generate_ed_link_cert(options, now, 0);
+  tt_assert(get_master_identity_key());
+
+  tt_int_op(0, OP_EQ, check_private_dir(ddir, CPD_CREATE, NULL));
+
+  /* Write fingerprint file */
+  tt_int_op(0, OP_EQ, router_write_fingerprint(0, 1));
+  cp = read_file_to_str(get_fname("write_fingerprint/fingerprint-ed25519"),
+                        0, NULL);
+  digest256_to_base64(ed25519_id,
+                      (const char *) get_master_identity_key()->pubkey);
+  tor_asprintf(&cp2, "haflinger %s\n", ed25519_id);
+  tt_str_op(cp, OP_EQ, cp2);
+  tor_free(cp);
+  tor_free(cp2);
+
+ done:
+  crypto_pk_free(key);
+  set_client_identity_key(NULL);
+  tor_free(cp);
+  tor_free(cp2);
+  routerkeys_free_all();
+}
+
 static void
 test_routerkeys_ed_certs(void *args)
 {
@@ -695,6 +741,7 @@ test_routerkeys_rsa_ed_crosscert(void *arg)
 
 struct testcase_t routerkeys_tests[] = {
   TEST(write_fingerprint, TT_FORK),
+  TEST(write_ed25519_identity, TT_FORK),
   TEST(ed_certs, TT_FORK),
   TEST(ed_key_create, TT_FORK),
   TEST(ed_key_init_basic, TT_FORK),