diff --git a/src/node/util.ts b/src/node/util.ts
index 93d82851..f575eb52 100644
--- a/src/node/util.ts
+++ b/src/node/util.ts
@@ -249,6 +249,31 @@ export async function handlePasswordValidation(
   return passwordValidation
 }
 
+export type IsCookieValidArgs = {
+  passwordMethod: PasswordMethod
+  cookieKey: string
+  hashedPasswordFromArgs: string | undefined
+  passwordFromArgs: string | undefined
+}
+
+/** Checks if a req.cookies.key is valid using the PasswordMethod */
+export async function isCookieValid(isCookieValidArgs: IsCookieValidArgs): Promise<boolean> {
+  let isValid = false
+  const { passwordFromArgs = "", cookieKey, hashedPasswordFromArgs = "" } = isCookieValidArgs
+  switch (isCookieValidArgs.passwordMethod) {
+    case "PLAIN_TEXT":
+      isValid = await isHashMatch(passwordFromArgs, cookieKey)
+      break
+    case "ARGON2":
+    case "SHA256":
+      isValid = safeCompare(cookieKey, hashedPasswordFromArgs)
+      break
+    default:
+      break
+  }
+  return isValid
+}
+
 const mimeTypes: { [key: string]: string } = {
   ".aac": "audio/x-aac",
   ".avi": "video/x-msvideo",
diff --git a/test/unit/node/util.test.ts b/test/unit/node/util.test.ts
index 5927ca32..0397fbff 100644
--- a/test/unit/node/util.test.ts
+++ b/test/unit/node/util.test.ts
@@ -6,6 +6,7 @@ import {
   getPasswordMethod,
   hashLegacy,
   isHashLegacyMatch,
+  isCookieValid,
 } from "../../../src/node/util"
 
 describe("getEnvPaths", () => {
@@ -234,7 +235,7 @@ describe("getPasswordMethod", () => {
   })
 })
 
-describe.only("handlePasswordValidation", () => {
+describe("handlePasswordValidation", () => {
   it("should return true with a hashedPassword for a PLAIN_TEXT password", async () => {
     const p = "password"
     const passwordValidation = await handlePasswordValidation({
@@ -322,3 +323,62 @@ describe.only("handlePasswordValidation", () => {
     expect(matchesHash).toBe(false)
   })
 })
+
+describe.only("isCookieValid", () => {
+  it("should be valid if hashed-password for SHA256 matches cookie.key", async () => {
+    const isValid = await isCookieValid({
+      passwordMethod: "SHA256",
+      cookieKey: "936a185caaa266bb9cbe981e9e05cb78cd732b0b3280eb944412bb6f8f8f07af",
+      hashedPasswordFromArgs: "936a185caaa266bb9cbe981e9e05cb78cd732b0b3280eb944412bb6f8f8f07af",
+      passwordFromArgs: undefined,
+    })
+    expect(isValid).toBe(true)
+  })
+  it("should be invalid if hashed-password for SHA256 does not match cookie.key", async () => {
+    const isValid = await isCookieValid({
+      passwordMethod: "SHA256",
+      cookieKey: "936a185caaa266bb9cbe981e9e05cb78cd732b0b3280eb9442bb6f8f8f07af",
+      hashedPasswordFromArgs: "936a185caaa266bb9cbe981e9e05cb78cd732b0b3280eb944412bb6f8f8f07af",
+      passwordFromArgs: undefined,
+    })
+    expect(isValid).toBe(false)
+  })
+  it("should be valid if hashed-password for ARGON2 matches cookie.key", async () => {
+    const isValid = await isCookieValid({
+      passwordMethod: "ARGON2",
+      cookieKey: "$argon2i$v=19$m=4096,t=3,p=1$0qR/o+0t00hsbJFQCKSfdQ$oFcM4rL6o+B7oxpuA4qlXubypbBPsf+8L531U7P9HYY",
+      hashedPasswordFromArgs:
+        "$argon2i$v=19$m=4096,t=3,p=1$0qR/o+0t00hsbJFQCKSfdQ$oFcM4rL6o+B7oxpuA4qlXubypbBPsf+8L531U7P9HYY",
+      passwordFromArgs: undefined,
+    })
+    expect(isValid).toBe(true)
+  })
+  it("should be invalid if hashed-password for ARGON2 does not match cookie.key", async () => {
+    const isValid = await isCookieValid({
+      passwordMethod: "ARGON2",
+      cookieKey: "$argon2i$v=19$m=4096,t=3,p=1$0qR/o+0t00hsbJFQCKSfdQ$oFcM4rL6o+B7oxpuA4qlXubypbBPsf+8L531U7P9H",
+      hashedPasswordFromArgs:
+        "$argon2i$v=19$m=4096,t=3,p=1$0qR/o+0t00hsbJFQCKSfdQ$oFcM4rL6o+B7oxpuA4qlXubypbBPsf+8L531U7P9HYY",
+      passwordFromArgs: undefined,
+    })
+    expect(isValid).toBe(false)
+  })
+  it("should be valid if password for PLAIN_TEXT matches cookie.key", async () => {
+    const isValid = await isCookieValid({
+      passwordMethod: "PLAIN_TEXT",
+      cookieKey: "$argon2i$v=19$m=4096,t=3,p=1$0qR/o+0t00hsbJFQCKSfdQ$oFcM4rL6o+B7oxpuA4qlXubypbBPsf+8L531U7P9HYY",
+      passwordFromArgs: "password",
+      hashedPasswordFromArgs: undefined,
+    })
+    expect(isValid).toBe(true)
+  })
+  it("should be invalid if hashed-password for PLAIN_TEXT does not match cookie.key", async () => {
+    const isValid = await isCookieValid({
+      passwordMethod: "PLAIN_TEXT",
+      cookieKey: "$argon2i$v=19$m=4096,t=3,p=1$0qR/o+0t00hsbJFQCKSfdQ$oFcM4rL6o+B7oxpuA4qlXubypbBPsf+8L531U7P9H",
+      passwordFromArgs: "password1234",
+      hashedPasswordFromArgs: undefined,
+    })
+    expect(isValid).toBe(false)
+  })
+})