From 158bf81343054982800d44d507e8e50f2eeb6dd4 Mon Sep 17 00:00:00 2001 From: Dennis Brentjes Date: Thu, 27 Oct 2016 13:14:28 +0200 Subject: Added proper keyexchange for elgamal-gcrypt. --- libcmix-crypto/CMakeLists.txt | 2 +- libcmix-crypto/api.h | 22 ++++++- libcmix-crypto/curve25519/curve25519.c | 3 + libcmix-crypto/curve25519/curve25519.h | 3 +- .../curve25519/sodium/libsodium_curve25519.c | 8 +-- libcmix-crypto/elgamal/elgamal.c | 3 + libcmix-crypto/elgamal/elgamal.h | 21 ++++++- libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c | 69 ++++++++++++++++++---- 8 files changed, 110 insertions(+), 21 deletions(-) (limited to 'libcmix-crypto') diff --git a/libcmix-crypto/CMakeLists.txt b/libcmix-crypto/CMakeLists.txt index 65b00ab..08036f4 100644 --- a/libcmix-crypto/CMakeLists.txt +++ b/libcmix-crypto/CMakeLists.txt @@ -32,7 +32,7 @@ target_sources(cmix-crypto INTERFACE ${interface_sources} ) -option(UseEC "Use curve25519 instead of RSA" ON) +option(UseEC "Use curve25519 instead of RSA" OFF) if(UseEC) target_link_libraries(cmix-crypto diff --git a/libcmix-crypto/api.h b/libcmix-crypto/api.h index 5267f33..99f6417 100644 --- a/libcmix-crypto/api.h +++ b/libcmix-crypto/api.h @@ -31,7 +31,7 @@ typedef void (*KeyPairDeleter)(struct KeyPair*); * \brief Defines how a Derived Shared Key function should look like. * Used to store a pointer to function to a implementation. */ -typedef struct SharedKey (*SharedKeyDeriver)(struct KeyPair, void const*, bool); +typedef struct SharedKey (*SharedKeyDeriver)(struct KeyPair, unsigned char const*, size_t, unsigned char const*, size_t, void*, bool); /*! * \brief Defines how a Derived Shared Key deleter function should look like. @@ -54,6 +54,21 @@ typedef void(*KeyArrayGetter)(char**, size_t* size, void*); */ typedef void(*PublicShareAdder)(char**, size_t*, char const*, size_t, void*); +/*! + * + */ +typedef void*(*GroupElementGetter)(bool); + +/*! + * + */ +typedef void*(*KeyExchangeValueGetter)(void*); + +/*! + * + */ +typedef void(*GroupElementDeleter)(void*); + /*! * \brief The Api struct stores pointers to functions of a specific implementation. Like a Curve25519 specific one. */ @@ -61,7 +76,10 @@ struct Api { Initializer initialize; ///< Function that will initialize the crypto library. KeyPairCreator create_key_pair; ///< Pointer to keypair creation function KeyPairDeleter free_key_pair; ///< Pointer to keypair deletor function - KeyArrayGetter get_key_array; ///< Get the array representation of a public key; + KeyArrayGetter get_key_array; ///< Get the array representation of a public key + GroupElementGetter get_group_element; ///< get group element + KeyExchangeValueGetter get_key_exchange_value; ///< get generator *op* group element. + GroupElementDeleter free_group_element; ///< frees a base type of the cryptolibrary. PublicShareAdder add_public_share; ///< Adds the public key stored in void* to the existing share. SharedKeyDeriver derive_shared_key; ///< Pointer to shared key derivation function SharedKeyDeleter free_shared_key; ///< Pointer to shared key deleter function diff --git a/libcmix-crypto/curve25519/curve25519.c b/libcmix-crypto/curve25519/curve25519.c index c4fae8d..0036808 100644 --- a/libcmix-crypto/curve25519/curve25519.c +++ b/libcmix-crypto/curve25519/curve25519.c @@ -9,6 +9,9 @@ struct Api get_curve25519_implementation() &curve25519_create_keypair, &curve25519_keypair_deleter, &curve25519_get_key_array, + NULL, + NULL, + NULL, &curve25519_add_public_share, &curve25519_derive_shared_key, &curve25519_shared_key_deleter, diff --git a/libcmix-crypto/curve25519/curve25519.h b/libcmix-crypto/curve25519/curve25519.h index 5d004cf..2dc2e48 100644 --- a/libcmix-crypto/curve25519/curve25519.h +++ b/libcmix-crypto/curve25519/curve25519.h @@ -51,8 +51,7 @@ extern void curve25519_add_public_share(char** buffer, size_t* out_len, char con * \param swap_pub_order Should we swap the order in which we feed the public keys to the hash function. * \return A Shared key */ -extern struct SharedKey curve25519_derive_shared_key(struct KeyPair pair, void const* pub_key, bool swap_pub_order); - +extern struct SharedKey curve25519_derive_shared_key(struct KeyPair pair, unsigned char const* other_pub, size_t pub_len, unsigned char const* value, size_t value_len, void* priv_value, bool swap_pub_order); /*! * \brief curve25519_shared_key_deleter * \param s the Shared key to free. diff --git a/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c b/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c index 06453c5..0fbd387 100644 --- a/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c +++ b/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c @@ -47,25 +47,25 @@ void curve25519_add_public_share(char** buffer, size_t* out_len, char const* sha } -struct SharedKey curve25519_derive_shared_key(struct KeyPair pair, void const* pub_key, bool swap_pub_order) { +struct SharedKey curve25519_derive_shared_key(struct KeyPair pair, unsigned char const* other_pub, size_t pub_len, unsigned char const* value, size_t value_len, void* priv_value, bool swap_pub_order) { unsigned char* shared = (unsigned char*) sodium_malloc(crypto_generichash_BYTES); crypto_generichash_state h; unsigned char* scalarmult_q = (unsigned char*) sodium_malloc(crypto_scalarmult_BYTES); - if (crypto_scalarmult(scalarmult_q, (unsigned char const*) pair.sec, (unsigned char const*) pub_key) != 0) { + if (crypto_scalarmult(scalarmult_q, (unsigned char const*) priv_value, (unsigned char const*) value) != 0) { exit(-1); } crypto_generichash_init(&h, NULL, 0U, crypto_generichash_BYTES); crypto_generichash_update(&h, scalarmult_q, crypto_scalarmult_BYTES); if(swap_pub_order) { - crypto_generichash_update(&h, (unsigned char const*) pub_key, crypto_box_PUBLICKEYBYTES); + crypto_generichash_update(&h, (unsigned char const*) other_pub, crypto_box_PUBLICKEYBYTES); crypto_generichash_update(&h, (unsigned char const*) pair.pub, crypto_box_PUBLICKEYBYTES); } else { crypto_generichash_update(&h, (unsigned char const*) pair.pub, crypto_box_PUBLICKEYBYTES); - crypto_generichash_update(&h, (unsigned char const*) pub_key, crypto_box_PUBLICKEYBYTES); + crypto_generichash_update(&h, (unsigned char const*) other_pub, crypto_box_PUBLICKEYBYTES); } crypto_generichash_final(&h, shared, crypto_generichash_BYTES); diff --git a/libcmix-crypto/elgamal/elgamal.c b/libcmix-crypto/elgamal/elgamal.c index 8d10789..342659b 100644 --- a/libcmix-crypto/elgamal/elgamal.c +++ b/libcmix-crypto/elgamal/elgamal.c @@ -8,6 +8,9 @@ struct Api get_elgamal_implementation() &elgamal_create_keypair, &elgamal_keypair_deleter, &elgamal_get_key_array, + &elgamal_get_group_element, + &elgamal_get_key_exchange_value, + &elgamal_free_group_element, &elgamal_add_public_share, &elgamal_derive_shared_key, &elgamal_shared_key_deleter, diff --git a/libcmix-crypto/elgamal/elgamal.h b/libcmix-crypto/elgamal/elgamal.h index 0662827..dc2dd6f 100644 --- a/libcmix-crypto/elgamal/elgamal.h +++ b/libcmix-crypto/elgamal/elgamal.h @@ -35,6 +35,25 @@ extern void elgamal_keypair_deleter(struct KeyPair* p); */ extern void elgamal_get_key_array(char** buffer, size_t* len, void* pubkey); +/*! + * \brief get_group_element + * \param secure + * \return + */ +extern void* elgamal_get_group_element(bool secure); + +/*! + * \brief get_key_exchange_value + * \param group_el + * \return + */ +extern void* elgamal_get_key_exchange_value(void* group_el); + +/*! + * \brief elgamal_free_group_element + */ +extern void elgamal_free_group_element(void*); + /*! * \brief elgamal_add_public_share * \param buffer @@ -52,7 +71,7 @@ void elgamal_add_public_share(char** buffer, size_t* out_len, char const* share, * \param swap_pub_order Should we swap the order in which we feed the public keys to the hash function. * \return A Shared key */ -extern struct SharedKey elgamal_derive_shared_key(struct KeyPair pair, void const* pub_key, bool swap_pub_order); +extern struct SharedKey elgamal_derive_shared_key(struct KeyPair keypair, unsigned char const* other_pub, size_t pub_len, unsigned char const* value, size_t value_len, void* priv_value, bool swap); /*! * \brief elgamal_shared_key_deleter diff --git a/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c b/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c index 113fb95..ac90a51 100644 --- a/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c +++ b/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c @@ -43,10 +43,10 @@ void elgamal_initialize(void) { gcry_control (GCRYCTL_RESUME_SECMEM_WARN); gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0); - //leading as specified by libgcrypt - char p_hex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char q_hex[] = "008CF83642A709A097B447997640129DA299B1A47D1EB3750BA308B0FE64F5FBD3"; - char g_hex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leading 0 as specified by libgcrypt + char p_hex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char q_hex[] = "08CF83642A709A097B447997640129DA299B1A47D1EB3750BA308B0FE64F5FBD3"; + char g_hex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size_t nr_bytes_scanned; gcry_error_t error; @@ -77,9 +77,12 @@ struct KeyPair elgamal_create_keypair() { gcry_sexp_t priv_key; error = gcry_sexp_build(&priv_key, &parse_error_offset, "(private-key (elg (p %M) (g %M) (y %M) (x %M)))", p, g, y, x); check(error); - + error = gcry_pk_testkey(priv_key); check(error); + + gcry_sexp_release(priv_key); + gcry_free(bytes); return (struct KeyPair){ x, @@ -94,8 +97,8 @@ void elgamal_keypair_deleter(struct KeyPair* p) { p->pub = NULL; } -void elgamal_get_key_array(unsigned char** buffer, size_t* len, void* pubkey) { - gcry_mpi_t mpi = (gcry_mpi_t) pubkey; +void elgamal_get_key_array(unsigned char** buffer, size_t* len, void* key) { + gcry_mpi_t mpi = (gcry_mpi_t) key; gcry_error_t error; @@ -103,14 +106,41 @@ void elgamal_get_key_array(unsigned char** buffer, size_t* len, void* pubkey) { check(error); } +void* elgamal_get_group_element(bool secure) { + size_t parse_error_offset; + gcry_error_t error; + + void* bytes = gcry_random_bytes_secure(2048/8, GCRY_VERY_STRONG_RANDOM); + gcry_mpi_t a = secure ? gcry_mpi_snew(2048) : gcry_mpi_new(2048); + error = gcry_mpi_scan(&a, GCRYMPI_FMT_USG, bytes, 2048/8, &parse_error_offset); + check(error); + + gcry_free(bytes); + + return a; +} + +void elgamal_free_group_element(void* el) { + gcry_mpi_release((gcry_mpi_t) el); +} + +void* elgamal_get_key_exchange_value(void* group_el) { + gcry_mpi_t el = (gcry_mpi_t) group_el; + + gcry_mpi_t val = gcry_mpi_new(0); + gcry_mpi_powm(val, g, el, p); + + return val; +} + void elgamal_add_public_share(char** buffer, size_t* out_len, char const* share, size_t in_len, void* pubkey) { gcry_error_t error; + size_t parse_error_pos; gcry_mpi_t y = (gcry_mpi_t) pubkey; gcry_mpi_t mpi_share; - size_t parse_error_pos; error = gcry_mpi_scan(&mpi_share, GCRYMPI_FMT_USG, share, in_len, &parse_error_pos); check(error); @@ -126,12 +156,29 @@ void elgamal_shared_key_deleter(struct SharedKey* s) { s->shared = NULL; } -struct SharedKey elgamal_derive_shared_key(struct KeyPair pair, void const* pub_key, bool swap_pub_order) { + +struct SharedKey elgamal_derive_shared_key(struct KeyPair keypair, unsigned char const* other_pub, size_t pub_len, unsigned char const* value, size_t value_len, void* priv_value, bool swap) { + + gcry_error_t error; + size_t parse_error_pos; + + gcry_mpi_t ga; + error = gcry_mpi_scan(&ga, GCRYMPI_FMT_USG, value, value_len, &parse_error_pos); + check(error); + gcry_mpi_t b = (gcry_mpi_t) priv_value; + gcry_mpi_t gab = gcry_mpi_snew(0); + gcry_mpi_powm(gab, ga, b, p); + + gcry_mpi_release(ga); return (struct SharedKey){ - NULL, + gab }; } -void elgamal_deinitialize(void) {} +void elgamal_deinitialize(void) { + gcry_mpi_release(p); + gcry_mpi_release(q); + gcry_mpi_release(g); +} -- cgit v1.2.3-70-g09d2