diff options
Diffstat (limited to 'libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c')
| -rw-r--r-- | libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c | 82 |
1 files changed, 60 insertions, 22 deletions
diff --git a/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c b/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c index 1824ccc..8a6fb7e 100644 --- a/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c +++ b/libcmix-crypto/elgamal/gcrypt/gcrypt_elgamal.c @@ -9,6 +9,7 @@ static gcry_mpi_t p; static gcry_mpi_t q; static gcry_mpi_t g; +static unsigned int nr_bytes = 2; void check(gcry_error_t error) { if (error) { @@ -44,9 +45,13 @@ void gcrypt_elgamal_initialize(void) { gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0); //leading 0 as specified by libgcrypt - char p_hex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char q_hex[] = "08CF83642A709A097B447997640129DA299B1A47D1EB3750BA308B0FE64F5FBD3"; - char g_hex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char p_hex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char q_hex[] = "08CF83642A709A097B447997640129DA299B1A47D1EB3750BA308B0FE64F5FBD3"; + //char g_hex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char p_hex[] = "0b"; + char q_hex[] = "00"; + char g_hex[] = "02"; size_t nr_bytes_scanned; gcry_error_t error; @@ -66,11 +71,15 @@ struct KeyPair gcrypt_elgamal_create_keypair() { size_t parse_error_offset; gcry_error_t error; - void* bytes = gcry_random_bytes_secure(2048/8, GCRY_VERY_STRONG_RANDOM); - gcry_mpi_t x; - error = gcry_mpi_scan(&x, GCRYMPI_FMT_USG, bytes, 2048/8, &parse_error_offset); - check(error); - + gcry_mpi_t x = NULL; + do { + gcry_mpi_release(x); + void* bytes = gcry_random_bytes_secure(nr_bytes, GCRY_VERY_STRONG_RANDOM); + error = gcry_mpi_scan(&x, GCRYMPI_FMT_USG, bytes, nr_bytes, &parse_error_offset); + gcry_free(bytes); + check(error); + gcry_mpi_mod(x, x, p); //bias needs to be removed. + } while(gcry_mpi_cmp_ui(x, 0) == 0 || gcry_mpi_cmp(x, p) != -1); gcry_mpi_t y = gcry_mpi_new(0); gcry_mpi_powm(y, g, x, p); @@ -82,7 +91,6 @@ struct KeyPair gcrypt_elgamal_create_keypair() { check(error); gcry_sexp_release(priv_key); - gcry_free(bytes); return (struct KeyPair){ x, @@ -115,7 +123,7 @@ void* gcrypt_elgamal_array_to_element(char const* buffer, size_t len, bool secur gcry_mpi_t mpi; error = gcry_mpi_scan(&mpi, GCRYMPI_FMT_USG, buffer, len, &error_pos); - gcry_mpi_set_flag(mpi, GCRYMPI_FLAG_SECURE); + //gcry_mpi_set_flag(mpi, GCRYMPI_FLAG_SECURE); check(error); return mpi; @@ -125,14 +133,18 @@ void* gcrypt_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; - error = gcry_mpi_scan(&a, GCRYMPI_FMT_USG, bytes, 2048/8, &parse_error_offset); + gcry_mpi_t a = NULL; + do { + gcry_mpi_release(a); + void* bytes = gcry_random_bytes_secure(nr_bytes, GCRY_VERY_STRONG_RANDOM); + error = gcry_mpi_scan(&a, GCRYMPI_FMT_USG, bytes, nr_bytes, &parse_error_offset); + check(error); + gcry_mpi_mod(a, a, p); //BIAS REMOVE THIS. + gcry_free(bytes); + } while(gcry_mpi_cmp_ui(a, 0) == 0 || gcry_mpi_cmp(a, p) != -1); //random bytes generated with GCRY{,_VERY}_STRONG_RANDOM are generated in "secure memory" //so secure is unused. - check(error); - gcry_free(bytes); return a; } @@ -153,17 +165,21 @@ GroupElement gcrypt_elgamal_multiply(GroupElement lh, GroupElement rh, bool secu } GroupElement gcrypt_elgamal_get_decryption_share(GroupElement r, GroupElement e) { - gcry_mpi_t inve = gcry_mpi_snew(0); - gcry_mpi_invm(inve, (gcry_mpi_t)e, p); + //gcry_mpi_t inve = gcry_mpi_snew(0); + //gcry_mpi_invm(inve, (gcry_mpi_t)e, p); + + gcry_mpi_t inv_d = gcry_mpi_snew(0); + gcry_mpi_powm(inv_d, (gcry_mpi_t)r, (gcry_mpi_t)e, p); gcry_mpi_t d = gcry_mpi_snew(0); - gcry_mpi_powm(d, (gcry_mpi_t)r, inve, p); - gcry_mpi_release(inve); + gcry_mpi_invm(d, inv_d, p); + + gcry_mpi_release(inv_d); return d; } size_t gcrypt_elgamal_get_group_element_array_size() { - return 256u; + return nr_bytes; } void gcrypt_elgamal_delete_group_element(void* el) { @@ -213,7 +229,22 @@ void gcrypt_elgamal_delete_shared_key(struct SharedKey* s) { } void gcrypt_elgamal_encrypt(GroupElement* random_element, GroupElement* message_element, GroupElement value, GroupElement key) { - gcry_error_t error; + + GroupElement random = gcrypt_elgamal_get_group_element(true); + + *random_element = gcry_mpi_new(0); + gcry_mpi_powm((gcry_mpi_t) *random_element, g, (gcry_mpi_t) random, p); + + gcry_mpi_t key_pow_random = gcry_mpi_snew(0); + gcry_mpi_powm(key_pow_random, (gcry_mpi_t) key, (gcry_mpi_t) random, p); + + *message_element = gcry_mpi_snew(0); + gcry_mpi_mulm((gcry_mpi_t)*message_element, (gcry_mpi_t) value, key_pow_random, p); + + gcry_mpi_release((gcry_mpi_t) random); + gcry_mpi_release(key_pow_random); + +/* gcry_error_t error; size_t parse_error_pos; gcry_sexp_t pubkey_expr; @@ -232,7 +263,13 @@ void gcrypt_elgamal_encrypt(GroupElement* random_element, GroupElement* message_ gcry_sexp_release(enc_expr); gcry_sexp_release(value_expr); - gcry_sexp_release(pubkey_expr); + gcry_sexp_release(pubkey_expr); */ +} + +GroupElement gcrypt_elgamal_invert(GroupElement const x) { + gcry_mpi_t inv_x = gcry_mpi_new(0); + gcry_mpi_invm(inv_x, (gcry_mpi_t)x, p); + return inv_x; } void gcrypt_elgamal_deinitialize(void) { @@ -257,4 +294,5 @@ PublicShareAdder elgamal_add_public_share = &gcrypt_elgamal_add_public_share; SharedKeyDeriver elgamal_derive_shared_key = &gcrypt_elgamal_derive_shared_key; SharedKeyDeleter elgamal_delete_shared_key = &gcrypt_elgamal_delete_shared_key; Encrypter elgamal_encrypt = &gcrypt_elgamal_encrypt; +Inverter elgamal_invert = &gcrypt_elgamal_invert; Deinitializer elgamal_deinitialize = &gcrypt_elgamal_deinitialize;
\ No newline at end of file |