What encryption standards are used in passkey-based auth?

Q: What encryption standards are used in passkey-based auth?

Passkey-based authentication relies on FIDO2 and WebAuthn protocols, leveraging strong public-key cryptography. It uses asymmetric key pairs where the private key is securely stored in a Trusted Platform Module (TPM) or Secure Enclave and never leaves the user's device. Supported encryption algorithms include RSA (2048-bit or higher), ECDSA (256-bit), and EdDSA for secure authentication. Additionally, passkeys use SHA-256 for hashing and AES encryption for secure storage, ensuring strong protection against phishing, brute-force attacks, and credential theft.

What Encryption Standards Are Used in Passkey-Based Authentication?#

Passkey-based authentication relies on strong cryptographic standards to ensure security, privacy, and phishing resistance. Unlike traditional authentication methods that use passwords, passkeys employ public-key cryptography, which prevents credential theft and brute-force attacks.

1. FIDO2 and WebAuthn: The Foundation of Passkey Security#

Passkeys are built on the FIDO2 standard, which includes:

WebAuthn (Web Authentication API) – Defines how browsers and applications authenticate users with passkeys.
CTAP2 (Client to Authenticator Protocol 2) – Manages secure communication between devices and authenticators (e.g., biometric sensors, security keys).

These protocols ensure that passkeys are cryptographically bound to a user’s device and cannot be intercepted, replayed, or phished.

2. Public-Key Cryptography in Passkeys#

Passkeys use asymmetric cryptographic key pairs, where:

The private key is securely stored on the user’s device and never leaves it.
The public key is shared with the service (relying party) to verify authentication attempts.

3. Encryption Algorithms Used in Passkeys#

Passkey implementations support multiple cryptographic algorithms, ensuring security and performance:

Algorithm	Purpose	Strength
RSA (Rivest-Shamir-Adleman)	Public-key cryptography	2048-bit (or higher)
ECDSA (Elliptic Curve Digital Signature Algorithm)	Digital signatures	256-bit curve
EdDSA (Edwards-Curve Digital Signature Algorithm)	Faster authentication	255-bit or 448-bit curves
SHA-256 (Secure Hash Algorithm 256-bit)	Hashing and signing	256-bit hash
AES (Advanced Encryption Standard)	Secure storage	128-bit or 256-bit

These encryption methods make passkeys resistant to brute-force attacks and quantum computing threats (when using post-quantum cryptography enhancements).

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4. Secure Key Storage: TPMs and Secure Enclaves#

To prevent theft or tampering, passkeys are stored in hardware-backed security modules, such as:

TPM (Trusted Platform Module) – A secure chip embedded in devices.
Secure Enclaves (Apple, Android, Windows Hello) – Isolated storage that protects cryptographic keys.
HSM (Hardware Security Modules) – Used in enterprise-grade authentication solutions.

Because the private key never leaves the secure enclave, attackers cannot extract or steal passkeys remotely.

5. Why Passkey Cryptography Is More Secure Than Passwords#

Unlike traditional passwords, which are vulnerable to phishing, credential stuffing, and database leaks, passkeys:

Cannot be phished – The private key is never entered or exposed.
Are resistant to brute-force attacks – Even if a public key is known, decryption is infeasible.
Eliminate credential reuse risks – Passkeys are unique per service, preventing credential stuffing.

Conclusion#

Passkey-based authentication employs state-of-the-art encryption standards, including public-key cryptography (RSA, ECDSA, EdDSA), secure storage (TPMs, Secure Enclaves), and FIDO2/WebAuthn protocols. This ensures strong, phishing-resistant authentication while maintaining a seamless user experience.