diff options
Diffstat (limited to 'src/cipher.c')
| -rw-r--r-- | src/cipher.c | 153 |
1 files changed, 131 insertions, 22 deletions
diff --git a/src/cipher.c b/src/cipher.c index c9ea45b..5c23a36 100644 --- a/src/cipher.c +++ b/src/cipher.c @@ -44,6 +44,8 @@ #include <stdlib.h> #include <string.h> +#include <gmp.h> + int cipher_init(cipher_t* c, const char* type) { if(!c) @@ -52,19 +54,27 @@ int cipher_init(cipher_t* c, const char* type) c->type_ = unknown; if(!strcmp(type, "null")) c->type_ = null; -/* else if(!strcmp(type, "aes-ctr")) */ -/* c->type_ = aes_ctr; */ + else if(!strcmp(type, "aes-ctr")) + c->type_ = aes_ctr; else { log_printf(ERR, "unknown cipher type"); + return -1; } + c->key_length_ = 0; + c->handle_ = 0; + c->key_.buf_ = NULL; c->key_.length_ = 0; c->salt_.buf_ = NULL; c->salt_.length_ = 0; - return 0; + int ret = 0; + if(c->type_ == aes_ctr) + ret = cipher_aesctr_init(c, 128); + + return ret; } void cipher_set_key(cipher_t* c, u_int8_t* key, u_int32_t len) @@ -101,6 +111,8 @@ void cipher_set_salt(cipher_t* c, u_int8_t* salt, u_int32_t len) } memcpy(c->salt_.buf_, salt, len); c->salt_.length_ = len; + if(!c->salt_.buf_[0]) + c->salt_.buf_[0] = 1; // TODO: this is a outstandingly ugly workaround } void cipher_close(cipher_t* c) @@ -108,6 +120,9 @@ void cipher_close(cipher_t* c) if(!c) return; + if(c->type_ == aes_ctr) + cipher_aesctr_close(c); + if(c->key_.buf_) free(c->key_.buf_); if(c->salt_.buf_) @@ -120,13 +135,13 @@ void cipher_encrypt(cipher_t* c, plain_packet_t* in, encrypted_packet_t* out, se return; u_int32_t len; - if(c->type_ = null) - len = cipher_null_encrypt(plain_packet_get_packet(in), plain_packet_get_length(in), - encrypted_packet_get_payload(out), encrypted_packet_get_payload_length(out)); -/* else if(c->type_ = aes_ctr) */ -/* len = cipher_aesctr_encrypt(plain_packet_get_packet(in), plain_packet_get_length(in), */ -/* encrypted_packet_get_payload(out), encrypted_packet_get_payload_length(out), */ -/* seq_nr, sender_id, mux); */ + if(c->type_ == null) + len = cipher_null_crypt(plain_packet_get_packet(in), plain_packet_get_length(in), + encrypted_packet_get_payload(out), encrypted_packet_get_payload_length(out)); + else if(c->type_ == aes_ctr) + len = cipher_aesctr_crypt(c, plain_packet_get_packet(in), plain_packet_get_length(in), + encrypted_packet_get_payload(out), encrypted_packet_get_payload_length(out), + seq_nr, sender_id, mux); else { log_printf(ERR, "unknown cipher type"); return; @@ -145,14 +160,14 @@ void cipher_decrypt(cipher_t* c, encrypted_packet_t* in, plain_packet_t* out) return; u_int32_t len; - if(c->type_ = null) - len = cipher_null_decrypt(encrypted_packet_get_payload(in), encrypted_packet_get_payload_length(in), - plain_packet_get_packet(out), plain_packet_get_length(out)); -/* else if(c->type_ = aes_ctr) */ -/* len = cipher_aesctr_decrypt(encrypted_packet_get_payload(in), encrypted_packet_get_payload_length(in), */ -/* plain_packet_get_packet(out), plain_packet_get_length(out), */ -/* encrypted_packet_get_seq_nr(in), encrypted_packet_get_sender_id(in), */ -/* encrypted_packet_get_mux(in)); */ + if(c->type_ == null) + len = cipher_null_crypt(encrypted_packet_get_payload(in), encrypted_packet_get_payload_length(in), + plain_packet_get_packet(out), plain_packet_get_length(out)); + else if(c->type_ == aes_ctr) + len = cipher_aesctr_crypt(c, encrypted_packet_get_payload(in), encrypted_packet_get_payload_length(in), + plain_packet_get_packet(out), plain_packet_get_length(out), + encrypted_packet_get_seq_nr(in), encrypted_packet_get_sender_id(in), + encrypted_packet_get_mux(in)); else { log_printf(ERR, "unknown cipher type"); return; @@ -161,14 +176,108 @@ void cipher_decrypt(cipher_t* c, encrypted_packet_t* in, plain_packet_t* out) plain_packet_set_length(out, len); } -u_int32_t cipher_null_encrypt(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen) +/* ---------------- NULL Cipher ---------------- */ + +u_int32_t cipher_null_crypt(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen) { memcpy(out, in, (ilen < olen) ? ilen : olen); return (ilen < olen) ? ilen : olen; } -u_int32_t cipher_null_decrypt(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen) +/* ---------------- AES-Ctr Cipher ---------------- */ + +int cipher_aesctr_init(cipher_t* c, int key_length) { - memcpy(out, in, (ilen < olen) ? ilen : olen); - return (ilen < olen) ? ilen : olen; + c->key_length_ = key_length; + + int algo; + switch(key_length) { + case 128: algo = GCRY_CIPHER_AES128; break; + default: { + log_printf(ERR, "key length of %d Bits is not supported", key_length); + return -1; + } + } + + gcry_error_t err = gcry_cipher_open( &c->handle_, algo, GCRY_CIPHER_MODE_CTR, 0 ); + if(err) { + log_printf(ERR, "failed to open cipher: %s/%s", gcry_strerror(err), gcry_strsource(err)); + return -1; + } +} + +void cipher_aesctr_close(cipher_t* c) +{ + if(!c) + return; + + if(c->handle_) + gcry_cipher_close(c->handle_); +} + +buffer_t cipher_aesctr_calc_ctr(cipher_t* c, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux) +{ + buffer_t result; + result.buf_ = NULL; + result.length_ = 0; + + mpz_t ctr, sid_mux, seq; + mpz_init2(ctr, 128); + mpz_init2(sid_mux, 96); + mpz_init2(seq, 48); + + mpz_import(ctr, c->salt_.length_, 1, 1, 0, 0, c->salt_.buf_); + mpz_mul_2exp(ctr, ctr, 16); + + mpz_set_ui(sid_mux, mux); + mpz_mul_2exp(sid_mux, sid_mux, 16); + mpz_add_ui(sid_mux, sid_mux, sender_id); + mpz_mul_2exp(sid_mux, sid_mux, 64); + + mpz_set_ui(seq, seq_nr); + mpz_mul_2exp(seq, seq, 16); + + mpz_xor(ctr, ctr, sid_mux); + mpz_xor(ctr, ctr, seq); + + result.buf_ = mpz_export(NULL, (size_t*)&result.length_, 1, 1, 0, 0, ctr); + + mpz_clear(ctr); + mpz_clear(sid_mux); + mpz_clear(seq); + + return result; +} + +u_int32_t cipher_aesctr_crypt(cipher_t* c, u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux) +{ + if(!c) + return; + + gcry_error_t err = gcry_cipher_setkey(c->handle_, c->key_.buf_, c->key_.length_); + if(err) { + log_printf(ERR, "failed to set cipher key: %s/%s", gcry_strerror(err), gcry_strsource(err)); + return 0; + } + + buffer_t ctr = cipher_aesctr_calc_ctr(c, seq_nr, sender_id, mux); + if(!ctr.buf_) { + log_printf(ERR, "failed to calculate cipher CTR"); + return 0; + } + err = gcry_cipher_setctr(c->handle_, ctr.buf_, ctr.length_); + free(ctr.buf_); + + if(err) { + log_printf(ERR, "failed to set cipher CTR: %s/%s", gcry_strerror(err), gcry_strsource(err)); + return 0; + } + + err = gcry_cipher_encrypt(c->handle_, out, olen, in, ilen); + if(err) { + log_printf(ERR, "failed to generate cipher bitstream: %s/%s", gcry_strerror(err), gcry_strsource(err)); + return 0; + } + + return (ilen < olen) ? ilen : olen; } |