1 /* 2 --------------------------------------------------------------------------- 3 Copyright (c) 2002, Dr Brian Gladman < >, Worcester, UK. 4 All rights reserved. 5 6 LICENSE TERMS 7 8 The free distribution and use of this software in both source and binary 9 form is allowed (with or without changes) provided that: 10 11 1. distributions of this source code include the above copyright 12 notice, this list of conditions and the following disclaimer; 13 14 2. distributions in binary form include the above copyright 15 notice, this list of conditions and the following disclaimer 16 in the documentation and/or other associated materials; 17 18 3. the copyright holder's name is not used to endorse products 19 built using this software without specific written permission. 20 21 ALTERNATIVELY, provided that this notice is retained in full, this product 22 may be distributed under the terms of the GNU General Public License (GPL), 23 in which case the provisions of the GPL apply INSTEAD OF those given above. 24 25 DISCLAIMER 26 27 This software is provided 'as is' with no explicit or implied warranties 28 in respect of its properties, including, but not limited to, correctness 29 and/or fitness for purpose. 30 --------------------------------------------------------------------------- 31 Issue Date: 24/01/2003 32 33 This file contains the header file for fileenc.c, which implements password 34 based file encryption and authentication using AES in CTR mode, HMAC-SHA1 35 authentication and RFC2898 password based key derivation. 36 */ 37 38 #ifndef _FENC_H 39 #define _FENC_H 40 41 #include "aes.h" 42 #include "hmac.h" 43 #include "pwd2key.h" 44 45 #define BLOCK_SIZE AES_BLOCK_SIZE 46 #define PASSWORD_VERIFIER 47 48 #define MAX_KEY_LENGTH 32 49 #define MAX_PWD_LENGTH 128 50 #define MAX_SALT_LENGTH 16 51 #define KEYING_ITERATIONS 1000 52 53 #ifdef PASSWORD_VERIFIER 54 #define PWD_VER_LENGTH 2 55 #else 56 #define PWD_VER_LENGTH 0 57 #endif 58 59 #define GOOD_RETURN 0 60 #define PASSWORD_TOO_LONG -100 61 #define BAD_MODE -101 62 63 /* 64 Field lengths (in bytes) versus File Encryption Mode (0 < mode < 4) 65 66 Mode Key Salt MAC Overhead 67 1 16 8 10 18 68 2 24 12 10 22 69 3 32 16 10 26 70 71 The following macros assume that the mode value is correct. 72 */ 73 74 #define KEY_LENGTH(mode) (8 * (mode & 3) + 8) 75 #define SALT_LENGTH(mode) (4 * (mode & 3) + 4) 76 #define MAC_LENGTH(mode) (10) 77 78 /* the context for file encryption */ 79 80 typedef struct 81 { unsigned char nonce[BLOCK_SIZE]; /* the CTR nonce */ 82 unsigned char encr_bfr[BLOCK_SIZE]; /* encrypt buffer */ 83 aes_encrypt_ctx encr_ctx[1]; /* encryption context */ 84 hmac_ctx auth_ctx[1]; /* authentication context */ 85 unsigned int encr_pos; /* block position (enc) */ 86 unsigned int pwd_len; /* password length */ 87 unsigned int mode; /* File encryption mode */ 88 } fcrypt_ctx; 89 90 /* initialise file encryption or decryption */ 91 92 int fcrypt_init( 93 int mode, /* the mode to be used (input) */ 94 const unsigned char pwd[], /* the user specified password (input) */ 95 unsigned int pwd_len, /* the length of the password (input) */ 96 const unsigned char salt[], /* the salt (input) */ 97 #ifdef PASSWORD_VERIFIER 98 unsigned char pwd_ver[PWD_VER_LENGTH], /* 2 byte password verifier (output) */ 99 #endif 100 fcrypt_ctx cx[1]); /* the file encryption context (output) */ 101 102 /* perform 'in place' encryption or decryption and authentication */ 103 104 void fcrypt_encrypt(unsigned char data[], unsigned int data_len, fcrypt_ctx cx[1]); 105 void fcrypt_decrypt(unsigned char data[], unsigned int data_len, fcrypt_ctx cx[1]); 106 107 /* close encryption/decryption and return the MAC value */ 108 /* the return value is the length of the MAC */ 109 110 int fcrypt_end(unsigned char mac[], /* the MAC value (output) */ 111 fcrypt_ctx cx[1]); /* the context (input) */ 112 113 #endif 114 115