7.1.4. Validation of Inputs and Outputs

7.1.4. Validation of Inputs and Outputs

The following public keys are subject to validation if the group requires public key validation: the sender MUST validate the recipient's public key pkR; the recipient MUST validate the ephemeral public key pkE; in authenticated modes, the recipient MUST validate the sender's static public key pkS. Validation failure yields a ValidationError.

For P-256, P-384, and P-521, senders and recipients MUST perform partial public key validation on all public key inputs, as defined in Section 5.6.2.3.4 of [keyagreement]. This includes checking that the coordinates are in the correct range, that the point is on the curve, and that the point is not the point at infinity. Additionally, senders and recipients MUST ensure the Diffie-Hellman shared secret is not the point at infinity.

For X25519 and X448, public keys and Diffie-Hellman outputs MUST be validated as described in [RFC7748]. In particular, recipients MUST check whether the Diffie-Hellman shared secret is the all-zero value and abort if so.