diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index d81b495..947d322 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -12,6 +12,7 @@ model User {
   email         String    @unique
   passwordHash  String?
   name          String?
+  did           String?   @unique  // EncryptID DID (passkey identity)
   credits       Int       @default(0)
   lastCreditAt  DateTime  @default(now())
   emailVerified DateTime?
diff --git a/src/app/auth/signin/page.tsx b/src/app/auth/signin/page.tsx
index 1c8051f..9ee9e62 100644
--- a/src/app/auth/signin/page.tsx
+++ b/src/app/auth/signin/page.tsx
@@ -8,9 +8,11 @@ import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { Card, CardContent, CardDescription, CardFooter, CardHeader, CardTitle } from "@/components/ui/card";
-import { Loader2 } from "lucide-react";
+import { Loader2, Fingerprint } from "lucide-react";
 import { toast } from "sonner";
 
+const ENCRYPTID_SERVER = process.env.NEXT_PUBLIC_ENCRYPTID_SERVER_URL || "https://encryptid.jeffemmett.com";
+
 function SignInForm() {
   const router = useRouter();
   const searchParams = useSearchParams();
@@ -19,6 +21,7 @@ function SignInForm() {
   const [email, setEmail] = useState("");
   const [password, setPassword] = useState("");
   const [isLoading, setIsLoading] = useState(false);
+  const [isPasskeyLoading, setIsPasskeyLoading] = useState(false);
 
   async function handleSubmit(e: React.FormEvent) {
     e.preventDefault();
@@ -45,16 +48,129 @@ function SignInForm() {
     }
   }
 
+  async function handlePasskeySignIn() {
+    setIsPasskeyLoading(true);
+
+    try {
+      // Step 1: Get authentication options from EncryptID server
+      const startRes = await fetch(`${ENCRYPTID_SERVER}/api/auth/start`, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({}),
+      });
+      const { options } = await startRes.json();
+
+      // Step 2: Trigger WebAuthn ceremony in the browser
+      const challenge = Uint8Array.from(atob(options.challenge.replace(/-/g, "+").replace(/_/g, "/")), c => c.charCodeAt(0));
+
+      const publicKeyOptions: PublicKeyCredentialRequestOptions = {
+        challenge,
+        rpId: options.rpId,
+        userVerification: options.userVerification as UserVerificationRequirement,
+        timeout: options.timeout,
+        allowCredentials: options.allowCredentials?.map((c: { type: string; id: string; transports?: string[] }) => ({
+          type: c.type as PublicKeyCredentialType,
+          id: Uint8Array.from(atob(c.id.replace(/-/g, "+").replace(/_/g, "/")), ch => ch.charCodeAt(0)),
+          transports: c.transports as AuthenticatorTransport[],
+        })),
+      };
+
+      const assertion = await navigator.credentials.get({ publicKey: publicKeyOptions }) as PublicKeyCredential;
+      if (!assertion) throw new Error("Passkey authentication cancelled");
+
+      const response = assertion.response as AuthenticatorAssertionResponse;
+
+      // Helper to convert ArrayBuffer to base64url
+      function toBase64url(buffer: ArrayBuffer): string {
+        return btoa(String.fromCharCode(...new Uint8Array(buffer)))
+          .replace(/\+/g, "-")
+          .replace(/\//g, "_")
+          .replace(/=+$/, "");
+      }
+
+      // Step 3: Complete authentication with EncryptID server
+      const completeRes = await fetch(`${ENCRYPTID_SERVER}/api/auth/complete`, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({
+          challenge: options.challenge,
+          credential: {
+            credentialId: assertion.id,
+            authenticatorData: toBase64url(response.authenticatorData),
+            clientDataJSON: toBase64url(response.clientDataJSON),
+            signature: toBase64url(response.signature),
+            userHandle: response.userHandle ? toBase64url(response.userHandle) : null,
+          },
+        }),
+      });
+
+      const authResult = await completeRes.json();
+      if (!authResult.success) {
+        throw new Error(authResult.error || "Authentication failed");
+      }
+
+      // Step 4: Exchange EncryptID token for NextAuth session
+      const result = await signIn("encryptid", {
+        token: authResult.token,
+        redirect: false,
+      });
+
+      if (result?.error) {
+        toast.error("Passkey verified but session creation failed");
+      } else {
+        toast.success("Signed in with passkey!");
+        router.push(callbackUrl);
+        router.refresh();
+      }
+    } catch (error: any) {
+      if (error.name === "NotAllowedError") {
+        toast.error("Passkey authentication was cancelled");
+      } else {
+        toast.error(error.message || "Passkey authentication failed");
+      }
+    } finally {
+      setIsPasskeyLoading(false);
+    }
+  }
+
+  const anyLoading = isLoading || isPasskeyLoading;
+
   return (
     <Card className="w-full max-w-md">
       <CardHeader className="space-y-1">
         <CardTitle className="text-2xl font-bold">Sign in</CardTitle>
         <CardDescription>
-          Enter your email and password to access your account
+          Sign in with a passkey or your email and password
         </CardDescription>
       </CardHeader>
-      <form onSubmit={handleSubmit}>
-        <CardContent className="space-y-4">
+      <CardContent className="space-y-4">
+        {/* Passkey sign-in button */}
+        <Button
+          type="button"
+          variant="outline"
+          className="w-full gap-2"
+          onClick={handlePasskeySignIn}
+          disabled={anyLoading}
+        >
+          {isPasskeyLoading ? (
+            <Loader2 className="h-4 w-4 animate-spin" />
+          ) : (
+            <Fingerprint className="h-4 w-4" />
+          )}
+          Sign in with Passkey
+        </Button>
+
+        <div className="relative">
+          <div className="absolute inset-0 flex items-center">
+            <span className="w-full border-t" />
+          </div>
+          <div className="relative flex justify-center text-xs uppercase">
+            <span className="bg-background px-2 text-muted-foreground">Or continue with email</span>
+          </div>
+        </div>
+
+        {/* Email/password form */}
+        <form onSubmit={handleSubmit} className="space-y-4">
           <div className="space-y-2">
             <Label htmlFor="email">Email</Label>
             <Input
@@ -64,7 +180,7 @@ function SignInForm() {
               value={email}
               onChange={(e) => setEmail(e.target.value)}
               required
-              disabled={isLoading}
+              disabled={anyLoading}
             />
           </div>
           <div className="space-y-2">
@@ -75,23 +191,23 @@ function SignInForm() {
               value={password}
               onChange={(e) => setPassword(e.target.value)}
               required
-              disabled={isLoading}
+              disabled={anyLoading}
             />
           </div>
-        </CardContent>
-        <CardFooter className="flex flex-col space-y-4">
-          <Button type="submit" className="w-full" disabled={isLoading}>
+          <Button type="submit" className="w-full" disabled={anyLoading}>
             {isLoading && <Loader2 className="mr-2 h-4 w-4 animate-spin" />}
             Sign in
           </Button>
-          <p className="text-sm text-muted-foreground text-center">
-            Don&apos;t have an account?{" "}
-            <Link href="/auth/signup" className="text-primary hover:underline">
-              Sign up
-            </Link>
-          </p>
-        </CardFooter>
-      </form>
+        </form>
+      </CardContent>
+      <CardFooter>
+        <p className="text-sm text-muted-foreground text-center w-full">
+          Don&apos;t have an account?{" "}
+          <Link href="/auth/signup" className="text-primary hover:underline">
+            Sign up
+          </Link>
+        </p>
+      </CardFooter>
     </Card>
   );
 }
diff --git a/src/app/auth/signup/page.tsx b/src/app/auth/signup/page.tsx
index ffbbc45..3e2eb27 100644
--- a/src/app/auth/signup/page.tsx
+++ b/src/app/auth/signup/page.tsx
@@ -8,9 +8,11 @@ import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { Card, CardContent, CardDescription, CardFooter, CardHeader, CardTitle } from "@/components/ui/card";
-import { Loader2 } from "lucide-react";
+import { Loader2, Fingerprint } from "lucide-react";
 import { toast } from "sonner";
 
+const ENCRYPTID_SERVER = process.env.NEXT_PUBLIC_ENCRYPTID_SERVER_URL || "https://encryptid.jeffemmett.com";
+
 export default function SignUpPage() {
   const router = useRouter();
 
@@ -19,6 +21,7 @@ export default function SignUpPage() {
   const [password, setPassword] = useState("");
   const [confirmPassword, setConfirmPassword] = useState("");
   const [isLoading, setIsLoading] = useState(false);
+  const [isPasskeyLoading, setIsPasskeyLoading] = useState(false);
 
   async function handleSubmit(e: React.FormEvent) {
     e.preventDefault();
@@ -71,6 +74,101 @@ export default function SignUpPage() {
     }
   }
 
+  async function handlePasskeyRegister() {
+    setIsPasskeyLoading(true);
+
+    try {
+      const username = name || `user-${Date.now().toString(36)}`;
+
+      // Step 1: Get registration options from EncryptID server
+      const startRes = await fetch(`${ENCRYPTID_SERVER}/api/register/start`, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ username, displayName: name || username }),
+      });
+      const { options, userId } = await startRes.json();
+
+      // Step 2: Trigger WebAuthn registration ceremony in the browser
+      function fromBase64url(str: string): Uint8Array {
+        return Uint8Array.from(atob(str.replace(/-/g, "+").replace(/_/g, "/")), c => c.charCodeAt(0));
+      }
+
+      const publicKeyOptions: PublicKeyCredentialCreationOptions = {
+        challenge: fromBase64url(options.challenge),
+        rp: options.rp,
+        user: {
+          id: fromBase64url(options.user.id),
+          name: options.user.name,
+          displayName: options.user.displayName,
+        },
+        pubKeyCredParams: options.pubKeyCredParams,
+        authenticatorSelection: options.authenticatorSelection,
+        timeout: options.timeout,
+        attestation: options.attestation as AttestationConveyancePreference,
+      };
+
+      const credential = await navigator.credentials.create({ publicKey: publicKeyOptions }) as PublicKeyCredential;
+      if (!credential) throw new Error("Passkey registration cancelled");
+
+      const response = credential.response as AuthenticatorAttestationResponse;
+
+      function toBase64url(buffer: ArrayBuffer): string {
+        return btoa(String.fromCharCode(...new Uint8Array(buffer)))
+          .replace(/\+/g, "-")
+          .replace(/\//g, "_")
+          .replace(/=+$/, "");
+      }
+
+      // Step 3: Complete registration with EncryptID server
+      const completeRes = await fetch(`${ENCRYPTID_SERVER}/api/register/complete`, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({
+          challenge: options.challenge,
+          userId,
+          username,
+          credential: {
+            credentialId: credential.id,
+            publicKey: toBase64url(response.getPublicKey?.() || response.attestationObject),
+            attestationObject: toBase64url(response.attestationObject),
+            clientDataJSON: toBase64url(response.clientDataJSON),
+            transports: (response as any).getTransports?.() || [],
+          },
+        }),
+      });
+
+      const regResult = await completeRes.json();
+      if (!regResult.success) {
+        throw new Error(regResult.error || "Registration failed");
+      }
+
+      // Step 4: Exchange EncryptID token for NextAuth session
+      const result = await signIn("encryptid", {
+        token: regResult.token,
+        redirect: false,
+      });
+
+      if (result?.error) {
+        toast.error("Passkey registered but session creation failed");
+        router.push("/auth/signin");
+      } else {
+        toast.success("Account created with passkey! Welcome to rVote.");
+        router.push("/");
+        router.refresh();
+      }
+    } catch (error: any) {
+      if (error.name === "NotAllowedError") {
+        toast.error("Passkey registration was cancelled");
+      } else {
+        toast.error(error.message || "Passkey registration failed");
+      }
+    } finally {
+      setIsPasskeyLoading(false);
+    }
+  }
+
+  const anyLoading = isLoading || isPasskeyLoading;
+
   return (
     <div className="flex min-h-[60vh] items-center justify-center">
       <Card className="w-full max-w-md">
@@ -80,19 +178,45 @@ export default function SignUpPage() {
             Join rVote to start ranking and voting on proposals
           </CardDescription>
         </CardHeader>
-        <form onSubmit={handleSubmit}>
-          <CardContent className="space-y-4">
-            <div className="space-y-2">
-              <Label htmlFor="name">Name (optional)</Label>
-              <Input
-                id="name"
-                type="text"
-                placeholder="Your name"
-                value={name}
-                onChange={(e) => setName(e.target.value)}
-                disabled={isLoading}
-              />
+        <CardContent className="space-y-4">
+          {/* Passkey registration */}
+          <div className="space-y-2">
+            <Label htmlFor="passkey-name">Display Name</Label>
+            <Input
+              id="passkey-name"
+              type="text"
+              placeholder="Your name"
+              value={name}
+              onChange={(e) => setName(e.target.value)}
+              disabled={anyLoading}
+            />
+          </div>
+          <Button
+            type="button"
+            variant="outline"
+            className="w-full gap-2"
+            onClick={handlePasskeyRegister}
+            disabled={anyLoading}
+          >
+            {isPasskeyLoading ? (
+              <Loader2 className="h-4 w-4 animate-spin" />
+            ) : (
+              <Fingerprint className="h-4 w-4" />
+            )}
+            Sign up with Passkey
+          </Button>
+
+          <div className="relative">
+            <div className="absolute inset-0 flex items-center">
+              <span className="w-full border-t" />
             </div>
+            <div className="relative flex justify-center text-xs uppercase">
+              <span className="bg-background px-2 text-muted-foreground">Or sign up with email</span>
+            </div>
+          </div>
+
+          {/* Email/password form */}
+          <form onSubmit={handleSubmit} className="space-y-4">
             <div className="space-y-2">
               <Label htmlFor="email">Email</Label>
               <Input
@@ -102,7 +226,7 @@ export default function SignUpPage() {
                 value={email}
                 onChange={(e) => setEmail(e.target.value)}
                 required
-                disabled={isLoading}
+                disabled={anyLoading}
               />
             </div>
             <div className="space-y-2">
@@ -114,7 +238,7 @@ export default function SignUpPage() {
                 value={password}
                 onChange={(e) => setPassword(e.target.value)}
                 required
-                disabled={isLoading}
+                disabled={anyLoading}
               />
             </div>
             <div className="space-y-2">
@@ -125,26 +249,26 @@ export default function SignUpPage() {
                 value={confirmPassword}
                 onChange={(e) => setConfirmPassword(e.target.value)}
                 required
-                disabled={isLoading}
+                disabled={anyLoading}
               />
             </div>
             <p className="text-sm text-muted-foreground">
               You&apos;ll start with <strong>50 credits</strong> and earn 10 more each day.
             </p>
-          </CardContent>
-          <CardFooter className="flex flex-col space-y-4">
-            <Button type="submit" className="w-full" disabled={isLoading}>
+            <Button type="submit" className="w-full" disabled={anyLoading}>
               {isLoading && <Loader2 className="mr-2 h-4 w-4 animate-spin" />}
               Create account
             </Button>
-            <p className="text-sm text-muted-foreground text-center">
-              Already have an account?{" "}
-              <Link href="/auth/signin" className="text-primary hover:underline">
-                Sign in
-              </Link>
-            </p>
-          </CardFooter>
-        </form>
+          </form>
+        </CardContent>
+        <CardFooter>
+          <p className="text-sm text-muted-foreground text-center w-full">
+            Already have an account?{" "}
+            <Link href="/auth/signin" className="text-primary hover:underline">
+              Sign in
+            </Link>
+          </p>
+        </CardFooter>
       </Card>
     </div>
   );
diff --git a/src/lib/auth.ts b/src/lib/auth.ts
index 0e20212..5c2489a 100644
--- a/src/lib/auth.ts
+++ b/src/lib/auth.ts
@@ -3,6 +3,7 @@ import Credentials from "next-auth/providers/credentials";
 import { PrismaAdapter } from "@auth/prisma-adapter";
 import { prisma } from "./prisma";
 import bcrypt from "bcryptjs";
+import { verifyEncryptIDToken } from "./encryptid";
 
 export const { handlers, signIn, signOut, auth } = NextAuth({
   adapter: PrismaAdapter(prisma),
@@ -15,7 +16,9 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
     error: "/auth/error",
   },
   providers: [
+    // Email + password login
     Credentials({
+      id: "credentials",
       name: "credentials",
       credentials: {
         email: { label: "Email", type: "email" },
@@ -50,6 +53,52 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
         };
       },
     }),
+
+    // EncryptID passkey login
+    Credentials({
+      id: "encryptid",
+      name: "EncryptID Passkey",
+      credentials: {
+        token: { label: "Token", type: "text" },
+      },
+      async authorize(credentials) {
+        if (!credentials?.token) {
+          return null;
+        }
+
+        // Verify the EncryptID JWT
+        const claims = await verifyEncryptIDToken(credentials.token as string);
+        if (!claims) {
+          return null;
+        }
+
+        const did = claims.did || claims.sub;
+
+        // Find existing user by DID or create a new one
+        let user = await prisma.user.findFirst({
+          where: { did },
+        });
+
+        if (!user) {
+          // Create new passkey-only user
+          user = await prisma.user.create({
+            data: {
+              email: `${did}@encryptid.local`, // Placeholder email for DID-only users
+              did,
+              name: claims.username || null,
+              credits: 50, // Starting credits
+              emailVerified: new Date(),
+            },
+          });
+        }
+
+        return {
+          id: user.id,
+          email: user.email,
+          name: user.name,
+        };
+      },
+    }),
   ],
   callbacks: {
     async jwt({ token, user }) {
diff --git a/src/lib/encryptid.ts b/src/lib/encryptid.ts
new file mode 100644
index 0000000..5b494b6
--- /dev/null
+++ b/src/lib/encryptid.ts
@@ -0,0 +1,38 @@
+/**
+ * EncryptID configuration for rvote-online
+ */
+
+export const ENCRYPTID_SERVER_URL =
+  process.env.ENCRYPTID_SERVER_URL || 'https://encryptid.jeffemmett.com';
+
+/**
+ * Verify an EncryptID JWT token by calling the EncryptID server.
+ * Returns claims if valid, null if invalid.
+ */
+export async function verifyEncryptIDToken(token: string): Promise<{
+  sub: string;
+  username?: string;
+  did?: string;
+  exp?: number;
+} | null> {
+  try {
+    const res = await fetch(`${ENCRYPTID_SERVER_URL}/api/session/verify`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ token }),
+    });
+
+    const data = await res.json();
+    if (data.valid) {
+      return {
+        sub: data.userId,
+        username: data.username,
+        did: data.did,
+        exp: data.exp,
+      };
+    }
+    return null;
+  } catch {
+    return null;
+  }
+}