diff --git a/src/node/hooks/express.js b/src/node/hooks/express.js
index b64ab5f3d..98be763c2 100644
--- a/src/node/hooks/express.js
+++ b/src/node/hooks/express.js
@@ -1,7 +1,7 @@
 'use strict';
 
 const _ = require('underscore');
-const SecretRotator = require('../utils/SecretRotator');
+const SecretRotator = require('../security/SecretRotator');
 const cookieParser = require('cookie-parser');
 const events = require('events');
 const express = require('express');
diff --git a/src/node/utils/SecretRotator.js b/src/node/security/SecretRotator.js
similarity index 100%
rename from src/node/utils/SecretRotator.js
rename to src/node/security/SecretRotator.js
diff --git a/src/node/security/crypto.js b/src/node/security/crypto.js
new file mode 100644
index 000000000..ebe918509
--- /dev/null
+++ b/src/node/security/crypto.js
@@ -0,0 +1,15 @@
+'use strict';
+
+const crypto = require('crypto');
+const util = require('util');
+
+
+/**
+ * Promisified version of Node.js's crypto.hkdf.
+ */
+exports.hkdf = util.promisify(crypto.hkdf);
+
+/**
+ * Promisified version of Node.js's crypto.randomBytes
+ */
+exports.randomBytes = util.promisify(crypto.randomBytes);
\ No newline at end of file
diff --git a/src/node/utils/crypto.js b/src/node/utils/crypto.js
deleted file mode 100644
index 071b450b1..000000000
--- a/src/node/utils/crypto.js
+++ /dev/null
@@ -1,43 +0,0 @@
-'use strict';
-
-const {Buffer} = require('buffer');
-const crypto = require('crypto');
-const util = require('util');
-
-// TODO: Delete this once support for Node.js < 15.0.0 is dropped.
-const hkdfFallback = async (digest, ikm, salt, info, keylen) => {
-  // https://datatracker.ietf.org/doc/html/rfc5869#section-2.2
-  const prkHmac = crypto.createHmac(digest, salt);
-  prkHmac.update(ikm);
-  const prk = prkHmac.digest();
-
-  // https://datatracker.ietf.org/doc/html/rfc5869#section-2.3
-  let len = 0;
-  const t = [Buffer.alloc(0)];
-  while (len < keylen) {
-    const hmac = crypto.createHmac(digest, prk);
-    hmac.update(t[t.length - 1]);
-    hmac.update(info);
-    hmac.update(Buffer.from([t.length % 256]));
-    const tn = hmac.digest();
-    t.push(tn);
-    len += tn.length;
-  }
-  const buf = Buffer.concat(t);
-  return (buf.byteOffset === 0 && buf.buffer.byteLength === keylen
-    ? buf : Uint8Array.prototype.slice.call(buf, 0, keylen)).buffer;
-};
-
-/**
- * Promisified version of Node.js's crypto.hkdf.
- */
-exports.hkdf = crypto.hkdf ? util.promisify(crypto.hkdf) : hkdfFallback;
-
-/**
- * Promisified version of Node.js's crypto.randomBytes
- */
-exports.randomBytes = util.promisify(crypto.randomBytes);
-
-exports.exportedForTesting = {
-  hkdfFallback,
-};
diff --git a/src/tests/backend/specs/SecretRotator.js b/src/tests/backend/specs/SecretRotator.js
index a371a4724..1831ef71f 100644
--- a/src/tests/backend/specs/SecretRotator.js
+++ b/src/tests/backend/specs/SecretRotator.js
@@ -1,9 +1,9 @@
 'use strict';
 
-const SecretRotator = require('../../../node/utils/SecretRotator');
+const SecretRotator = require('../../../node/security/SecretRotator');
 const assert = require('assert').strict;
 const common = require('../common');
-const crypto = require('../../../node/utils/crypto');
+const crypto = require('../../../node/security/crypto');
 const db = require('../../../node/db/DB');
 
 const logger = common.logger;
diff --git a/src/tests/backend/specs/crypto.js b/src/tests/backend/specs/crypto.js
index 6472b2e85..cde096f01 100644
--- a/src/tests/backend/specs/crypto.js
+++ b/src/tests/backend/specs/crypto.js
@@ -2,40 +2,10 @@
 
 const assert = require('assert').strict;
 const {Buffer} = require('buffer');
-const crypto = require('../../../node/utils/crypto');
+const crypto = require('../../../node/security/crypto');
 const nodeCrypto = require('crypto');
 const util = require('util');
 
 const nodeHkdf = nodeCrypto.hkdf ? util.promisify(nodeCrypto.hkdf) : null;
 
 const ab2hex = (ab) => Buffer.from(ab).toString('hex');
-
-describe(__filename, function () {
-  describe('hkdf fallback', function () {
-    before(async function () {
-      if (!nodeHkdf) this.skip();
-    });
-
-    const testCases = [
-      ['minimal', 'sha256', 1, 0, 0, 1],
-      ['huge', 'sha512', 1024, 1024, 1024, 16320],
-    ];
-
-    for (const [desc, digest, ikmLen, saltLen, infoLen, keyLen] of testCases) {
-      for (const strings of [false, true]) {
-        it(`${desc} (${strings ? 'strings' : 'buffers'})`, async function () {
-          let isi = await Promise.all([
-            crypto.randomBytes(ikmLen),
-            crypto.randomBytes(saltLen),
-            crypto.randomBytes(infoLen),
-          ]);
-          if (strings) isi = isi.map((b) => b.toString('hex').slice(0, b.length));
-          const args = [digest, ...isi, keyLen];
-          assert.equal(
-              ab2hex(await crypto.exportedForTesting.hkdfFallback(...args)),
-              ab2hex(await nodeHkdf(...args)));
-        });
-      }
-    }
-  });
-});