| // Copyright 2025 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CRYPTO_KEX_H_ |
| #define CRYPTO_KEX_H_ |
| |
| #include "base/containers/span.h" |
| #include "crypto/keypair.h" |
| |
| namespace crypto::kex { |
| |
| // Derives a shared secret using elliptic-curve Diffie Hellman from a public key |
| // and a private key, and stores it in the provided out span. The resulting |
| // secret is not processed in any way and is not appropriate to use directly as |
| // key material (not all of the bits are uniformly random). |
| // |
| // The caller is responsible for ensuring that `theirs` and `ours` are P-256 |
| // keys, e.g. with `IsEcP256`. Passing keys of the wrong type will cause the |
| // function to abort. Note that these conditions imply ECDH is infallible; |
| // `PublicKey` constructors enforce that P-256 keys are on the curve and not the |
| // point at infinity. |
| CRYPTO_EXPORT void EcdhP256(const crypto::keypair::PublicKey& theirs, |
| const crypto::keypair::PrivateKey& ours, |
| base::span<uint8_t, 32> out); |
| |
| } // namespace crypto::kex |
| |
| #endif // CRYPTO_KEX_H_ |
