/* Copyright (c) 2015, Google Inc. * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #ifndef OPENSSL_HEADER_CURVE25519_H #define OPENSSL_HEADER_CURVE25519_H #include <openssl/base.h> #if defined(__cplusplus) extern "C" { #endif // Curve25519. // // Curve25519 is an elliptic curve. See https://tools.ietf.org/html/rfc7748. // X25519. // // X25519 is the Diffie-Hellman primitive built from curve25519. It is // sometimes referred to as “curve25519”, but “X25519” is a more precise name. // See http://cr.yp.to/ecdh.html and https://tools.ietf.org/html/rfc7748. #define X25519_PRIVATE_KEY_LEN … #define X25519_PUBLIC_VALUE_LEN … #define X25519_SHARED_KEY_LEN … // X25519_keypair sets |out_public_value| and |out_private_key| to a freshly // generated, public–private key pair. OPENSSL_EXPORT void X25519_keypair(uint8_t out_public_value[32], uint8_t out_private_key[32]); // X25519 writes a shared key to |out_shared_key| that is calculated from the // given private key and the peer's public value. It returns one on success and // zero on error. // // Don't use the shared key directly, rather use a KDF and also include the two // public values as inputs. OPENSSL_EXPORT int X25519(uint8_t out_shared_key[32], const uint8_t private_key[32], const uint8_t peer_public_value[32]); // X25519_public_from_private calculates a Diffie-Hellman public value from the // given private key and writes it to |out_public_value|. OPENSSL_EXPORT void X25519_public_from_private(uint8_t out_public_value[32], const uint8_t private_key[32]); // Ed25519. // // Ed25519 is a signature scheme using a twisted-Edwards curve that is // birationally equivalent to curve25519. // // Note that, unlike RFC 8032's formulation, our private key representation // includes a public key suffix to make multiple key signing operations with the // same key more efficient. The RFC 8032 private key is referred to in this // implementation as the "seed" and is the first 32 bytes of our private key. #define ED25519_PRIVATE_KEY_LEN … #define ED25519_PUBLIC_KEY_LEN … #define ED25519_SIGNATURE_LEN … // ED25519_keypair sets |out_public_key| and |out_private_key| to a freshly // generated, public–private key pair. OPENSSL_EXPORT void ED25519_keypair(uint8_t out_public_key[32], uint8_t out_private_key[64]); // ED25519_sign sets |out_sig| to be a signature of |message_len| bytes from // |message| using |private_key|. It returns one on success or zero on // allocation failure. OPENSSL_EXPORT int ED25519_sign(uint8_t out_sig[64], const uint8_t *message, size_t message_len, const uint8_t private_key[64]); // ED25519_verify returns one iff |signature| is a valid signature, by // |public_key| of |message_len| bytes from |message|. It returns zero // otherwise. OPENSSL_EXPORT int ED25519_verify(const uint8_t *message, size_t message_len, const uint8_t signature[64], const uint8_t public_key[32]); // ED25519_keypair_from_seed calculates a public and private key from an // Ed25519 “seed”. Seed values are not exposed by this API (although they // happen to be the first 32 bytes of a private key) so this function is for // interoperating with systems that may store just a seed instead of a full // private key. OPENSSL_EXPORT void ED25519_keypair_from_seed(uint8_t out_public_key[32], uint8_t out_private_key[64], const uint8_t seed[32]); // SPAKE2. // // SPAKE2 is a password-authenticated key-exchange. It allows two parties, // who share a low-entropy secret (i.e. password), to agree on a shared key. // An attacker can only make one guess of the password per execution of the // protocol. // // See https://tools.ietf.org/html/draft-irtf-cfrg-spake2-02. // spake2_role_t enumerates the different “roles” in SPAKE2. The protocol // requires that the symmetry of the two parties be broken so one participant // must be “Alice” and the other be “Bob”. enum spake2_role_t { … }; // SPAKE2_CTX_new creates a new |SPAKE2_CTX| (which can only be used for a // single execution of the protocol). SPAKE2 requires the symmetry of the two // parties to be broken which is indicated via |my_role| – each party must pass // a different value for this argument. // // The |my_name| and |their_name| arguments allow optional, opaque names to be // bound into the protocol. For example MAC addresses, hostnames, usernames // etc. These values are not exposed and can avoid context-confusion attacks // when a password is shared between several devices. OPENSSL_EXPORT SPAKE2_CTX *SPAKE2_CTX_new( enum spake2_role_t my_role, const uint8_t *my_name, size_t my_name_len, const uint8_t *their_name, size_t their_name_len); // SPAKE2_CTX_free frees |ctx| and all the resources that it has allocated. OPENSSL_EXPORT void SPAKE2_CTX_free(SPAKE2_CTX *ctx); // SPAKE2_MAX_MSG_SIZE is the maximum size of a SPAKE2 message. #define SPAKE2_MAX_MSG_SIZE … // SPAKE2_generate_msg generates a SPAKE2 message given |password|, writes // it to |out| and sets |*out_len| to the number of bytes written. // // At most |max_out_len| bytes are written to |out| and, in order to ensure // success, |max_out_len| should be at least |SPAKE2_MAX_MSG_SIZE| bytes. // // This function can only be called once for a given |SPAKE2_CTX|. // // It returns one on success and zero on error. OPENSSL_EXPORT int SPAKE2_generate_msg(SPAKE2_CTX *ctx, uint8_t *out, size_t *out_len, size_t max_out_len, const uint8_t *password, size_t password_len); // SPAKE2_MAX_KEY_SIZE is the maximum amount of key material that SPAKE2 will // produce. #define SPAKE2_MAX_KEY_SIZE … // SPAKE2_process_msg completes the SPAKE2 exchange given the peer's message in // |their_msg|, writes at most |max_out_key_len| bytes to |out_key| and sets // |*out_key_len| to the number of bytes written. // // The resulting keying material is suitable for: // - Using directly in a key-confirmation step: i.e. each side could // transmit a hash of their role, a channel-binding value and the key // material to prove to the other side that they know the shared key. // - Using as input keying material to HKDF to generate a variety of subkeys // for encryption etc. // // If |max_out_key_key| is smaller than the amount of key material generated // then the key is silently truncated. If you want to ensure that no truncation // occurs then |max_out_key| should be at least |SPAKE2_MAX_KEY_SIZE|. // // You must call |SPAKE2_generate_msg| on a given |SPAKE2_CTX| before calling // this function. On successful return, |ctx| is complete and calling // |SPAKE2_CTX_free| is the only acceptable operation on it. // // Returns one on success or zero on error. OPENSSL_EXPORT int SPAKE2_process_msg(SPAKE2_CTX *ctx, uint8_t *out_key, size_t *out_key_len, size_t max_out_key_len, const uint8_t *their_msg, size_t their_msg_len); #if defined(__cplusplus) } // extern C extern "C++" { BSSL_NAMESPACE_BEGIN BORINGSSL_MAKE_DELETER(…) BSSL_NAMESPACE_END } // extern C++ #endif #endif // OPENSSL_HEADER_CURVE25519_H
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