/* * irc-sasl.c - SASL authentication with IRC server * * Copyright (C) 2003-2014 Sébastien Helleu * * This file is part of WeeChat, the extensible chat client. * * WeeChat is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 3 of the License, or * (at your option) any later version. * * WeeChat is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with WeeChat. If not, see . */ #include #include #include #include #include #include "../weechat-plugin.h" #include "irc.h" #include "irc-sasl.h" char *irc_sasl_mechanism_string[IRC_NUM_SASL_MECHANISMS] = { "plain", "dh-blowfish", "dh-aes", "external" }; /* * Builds answer for SASL authentication, using mechanism "PLAIN". * * Note: result must be freed after use. */ char * irc_sasl_mechanism_plain (const char *sasl_username, const char *sasl_password) { char *string, *answer_base64; int length_username, length; answer_base64 = NULL; length_username = strlen (sasl_username); length = ((length_username + 1) * 2) + strlen (sasl_password) + 1; string = malloc (length); if (string) { snprintf (string, length, "%s|%s|%s", sasl_username, sasl_username, sasl_password); string[length_username] = '\0'; string[(length_username * 2) + 1] = '\0'; answer_base64 = malloc (length * 4); if (answer_base64) weechat_string_encode_base64 (string, length - 1, answer_base64); free (string); } return answer_base64; } /* * Reads key sent by server (Diffie-Hellman key exchange). * * Returns: * 1: OK * 0: error */ int irc_sasl_dh (const char *data_base64, unsigned char **public_bin, unsigned char **secret_bin, int *length_key) { char *data; unsigned char *ptr_data; int length_data, size, num_bits_prime_number, rc; size_t num_written; gcry_mpi_t data_prime_number, data_generator_number, data_server_pub_key; gcry_mpi_t pub_key, priv_key, secret_mpi; rc = 0; data = NULL; data_prime_number = NULL; data_generator_number = NULL; data_server_pub_key = NULL; pub_key = NULL; priv_key = NULL; secret_mpi = NULL; /* decode data */ data = malloc (strlen (data_base64) + 1); length_data = weechat_string_decode_base64 (data_base64, data); ptr_data = (unsigned char *)data; /* extract prime number */ size = ntohs ((((unsigned int)ptr_data[1]) << 8) | ptr_data[0]); ptr_data += 2; length_data -= 2; if (size > length_data) goto dhend; data_prime_number = gcry_mpi_new (size * 8); gcry_mpi_scan (&data_prime_number, GCRYMPI_FMT_USG, ptr_data, size, NULL); num_bits_prime_number = gcry_mpi_get_nbits (data_prime_number); ptr_data += size; length_data -= size; /* extract generator number */ size = ntohs ((((unsigned int)ptr_data[1]) << 8) | ptr_data[0]); ptr_data += 2; length_data -= 2; if (size > length_data) goto dhend; data_generator_number = gcry_mpi_new (size * 8); gcry_mpi_scan (&data_generator_number, GCRYMPI_FMT_USG, ptr_data, size, NULL); ptr_data += size; length_data -= size; /* extract server-generated public key */ size = ntohs ((((unsigned int)ptr_data[1]) << 8) | ptr_data[0]); ptr_data += 2; length_data -= 2; if (size > length_data) goto dhend; data_server_pub_key = gcry_mpi_new (size * 8); gcry_mpi_scan (&data_server_pub_key, GCRYMPI_FMT_USG, ptr_data, size, NULL); /* generate keys */ pub_key = gcry_mpi_new (num_bits_prime_number); priv_key = gcry_mpi_new (num_bits_prime_number); gcry_mpi_randomize (priv_key, num_bits_prime_number, GCRY_STRONG_RANDOM); /* pub_key = (g ^ priv_key) % p */ gcry_mpi_powm (pub_key, data_generator_number, priv_key, data_prime_number); /* compute secret_bin */ *length_key = num_bits_prime_number / 8; *secret_bin = malloc (*length_key); secret_mpi = gcry_mpi_new (num_bits_prime_number); /* secret_mpi = (y ^ priv_key) % p */ gcry_mpi_powm (secret_mpi, data_server_pub_key, priv_key, data_prime_number); gcry_mpi_print (GCRYMPI_FMT_USG, *secret_bin, *length_key, &num_written, secret_mpi); /* create public_bin */ *public_bin = malloc (*length_key); gcry_mpi_print (GCRYMPI_FMT_USG, *public_bin, *length_key, &num_written, pub_key); rc = 1; dhend: if (data) free (data); if (data_prime_number) gcry_mpi_release (data_prime_number); if (data_generator_number) gcry_mpi_release (data_generator_number); if (data_server_pub_key) gcry_mpi_release (data_server_pub_key); if (pub_key) gcry_mpi_release (pub_key); if (priv_key) gcry_mpi_release (priv_key); if (secret_mpi) gcry_mpi_release (secret_mpi); return rc; } /* * Builds answer for SASL authentication, using mechanism "DH-BLOWFISH". * * Argument data_base64 is a concatenation of 3 strings, each string is composed * of 2 bytes (length of string), followed by content of string: * 1. a prime number * 2. a generator number * 3. server-generated public key * * Note: result must be freed after use. */ char * irc_sasl_mechanism_dh_blowfish (const char *data_base64, const char *sasl_username, const char *sasl_password) { char *answer, *ptr_answer, *answer_base64; unsigned char *password_clear, *password_crypted; int length_key, length_username, length_password, length_answer; unsigned char *public_bin, *secret_bin; gcry_cipher_hd_t gcrypt_handle; password_clear = NULL; password_crypted = NULL; answer = NULL; answer_base64 = NULL; secret_bin = NULL; public_bin = NULL; if (!irc_sasl_dh (data_base64, &public_bin, &secret_bin, &length_key)) goto bfend; /* create password buffers (clear and crypted) */ length_password = strlen (sasl_password) + ((8 - (strlen (sasl_password) % 8)) % 8); password_clear = malloc (length_password); password_crypted = malloc (length_password); memset (password_clear, 0, length_password); memset (password_crypted, 0, length_password); memcpy (password_clear, sasl_password, strlen (sasl_password)); /* crypt password using blowfish */ if (gcry_cipher_open (&gcrypt_handle, GCRY_CIPHER_BLOWFISH, GCRY_CIPHER_MODE_ECB, 0) != 0) goto bfend; if (gcry_cipher_setkey (gcrypt_handle, secret_bin, length_key) != 0) goto bfend; if (gcry_cipher_encrypt (gcrypt_handle, password_crypted, length_password, password_clear, length_password) != 0) goto bfend; gcry_cipher_close (gcrypt_handle); /* * build answer for server, it is concatenation of: * 1. key length (2 bytes) * 2. public key ('length_key' bytes) * 3. sasl_username ('length_username'+1 bytes) * 4. encrypted password ('length_password' bytes) */ length_username = strlen (sasl_username) + 1; length_answer = 2 + length_key + length_username + length_password; answer = malloc (length_answer); ptr_answer = answer; *((unsigned int *)ptr_answer) = htons(length_key); ptr_answer += 2; memcpy (ptr_answer, public_bin, length_key); ptr_answer += length_key; memcpy (ptr_answer, sasl_username, length_username); ptr_answer += length_username; memcpy (ptr_answer, password_crypted, length_password); /* encode answer to base64 */ answer_base64 = malloc (length_answer * 4); if (answer_base64) weechat_string_encode_base64 (answer, length_answer, answer_base64); bfend: if (secret_bin) free (secret_bin); if (public_bin) free (public_bin); if (password_clear) free (password_clear); if (password_crypted) free (password_crypted); if (answer) free (answer); return answer_base64; } /* * Builds answer for SASL authentication, using mechanism "DH-AES". * * Argument data_base64 is a concatenation of 3 strings, each string is composed * of 2 bytes (length of string), followed by content of string: * 1. a prime number * 2. a generator number * 3. server-generated public key * * Note: result must be freed after use. */ char * irc_sasl_mechanism_dh_aes (const char *data_base64, const char *sasl_username, const char *sasl_password) { char *answer, *ptr_answer, *answer_base64; unsigned char *ptr_userpass, *userpass_clear, *userpass_crypted; int length_key, length_answer; int length_username, length_password, length_userpass; unsigned char *public_bin, *secret_bin; char iv[16]; int cipher_algo; gcry_cipher_hd_t gcrypt_handle; userpass_clear = NULL; userpass_crypted = NULL; answer = NULL; answer_base64 = NULL; secret_bin = NULL; public_bin = NULL; if (irc_sasl_dh(data_base64, &public_bin, &secret_bin, &length_key) == 0) goto aesend; /* Select cipher algorithm: key length * 8 = cipher bit size */ switch (length_key) { case 32: cipher_algo = GCRY_CIPHER_AES256; break; case 24: cipher_algo = GCRY_CIPHER_AES192; break; case 16: cipher_algo = GCRY_CIPHER_AES128; break; default: /* Invalid bit length */ goto aesend; } /* Generate the IV */ gcry_randomize (iv, sizeof (iv), GCRY_STRONG_RANDOM); /* create user/pass buffers (clear and crypted) */ length_username = strlen (sasl_username) + 1; length_password = strlen (sasl_password) + 1; length_userpass = length_username + length_password + ((16 - ((length_username + length_password) % 16)) % 16); ptr_userpass = userpass_clear = malloc (length_userpass); userpass_crypted = malloc (length_userpass); memset (userpass_clear, 0, length_password); memset (userpass_crypted, 0, length_password); memcpy (ptr_userpass, sasl_username, length_username); ptr_userpass += length_username; memcpy (ptr_userpass, sasl_password, length_password); /* crypt password using AES in CBC mode */ if (gcry_cipher_open (&gcrypt_handle, cipher_algo, GCRY_CIPHER_MODE_CBC, 0) != 0) goto aesend; if (gcry_cipher_setkey (gcrypt_handle, secret_bin, length_key) != 0) goto aesend; if (gcry_cipher_setiv (gcrypt_handle, iv, sizeof(iv)) != 0) goto aesend; if (gcry_cipher_encrypt (gcrypt_handle, userpass_crypted, length_userpass, userpass_clear, length_userpass) != 0) goto aesend; gcry_cipher_close (gcrypt_handle); /* * build answer for server, it is concatenation of: * 1. key length (2 bytes) * 2. public key ('length_key' bytes) * 3. IV (sizeof (iv) bytes) * 4. encrypted password ('length_userpass' bytes) */ length_answer = 2 + length_key + sizeof (iv) + length_userpass; answer = malloc (length_answer); ptr_answer = answer; *((unsigned int *)ptr_answer) = htons(length_key); ptr_answer += 2; memcpy (ptr_answer, public_bin, length_key); ptr_answer += length_key; memcpy (ptr_answer, iv, sizeof (iv)); ptr_answer += sizeof (iv); memcpy (ptr_answer, userpass_crypted, length_userpass); /* encode answer to base64 */ answer_base64 = malloc (length_answer * 4); if (answer_base64) weechat_string_encode_base64 (answer, length_answer, answer_base64); aesend: if (secret_bin) free (secret_bin); if (public_bin) free (public_bin); if (userpass_clear) free (userpass_clear); if (userpass_crypted) free (userpass_crypted); if (answer) free (answer); return answer_base64; }