1 /****************************************************************************** 2 * Filename: sw_ecrypt-sync.h 3 * Revised: 2016-10-05 12:42:03 +0200 (Wed, 05 Oct 2016) 4 * Revision: 47308 5 ******************************************************************************/ 6 /* ecrypt-sync.h */ 7 8 /* 9 * Header file for synchronous stream ciphers without authentication 10 * mechanism. 11 * 12 * *** Please only edit parts marked with "[edit]". *** 13 */ 14 15 #ifndef ECRYPT_SYNC 16 #define ECRYPT_SYNC 17 18 #include "sw_ecrypt-portable.h" 19 20 /* ------------------------------------------------------------------------- */ 21 22 /* Cipher parameters */ 23 24 /* 25 * The name of your cipher. 26 */ 27 #define ECRYPT_NAME "ChaCha8" 28 #define ECRYPT_PROFILE "_____" 29 30 /* 31 * Specify which key and IV sizes are supported by your cipher. A user 32 * should be able to enumerate the supported sizes by running the 33 * following code: 34 * 35 * for (i = 0; ECRYPT_KEYSIZE(i) <= ECRYPT_MAXKEYSIZE; ++i) 36 * { 37 * keysize = ECRYPT_KEYSIZE(i); 38 * 39 * ... 40 * } 41 * 42 * All sizes are in bits. 43 */ 44 45 #define ECRYPT_MAXKEYSIZE 256 /* [edit] */ 46 #define ECRYPT_KEYSIZE(i) (128 + (i)*128) /* [edit] */ 47 48 #define ECRYPT_MAXIVSIZE 64 /* [edit] */ 49 #define ECRYPT_IVSIZE(i) (64 + (i)*64) /* [edit] */ 50 51 /* ------------------------------------------------------------------------- */ 52 53 /* Data structures */ 54 55 /* 56 * ECRYPT_ctx is the structure containing the representation of the 57 * internal state of your cipher. 58 */ 59 60 typedef struct 61 { 62 u32 input[16]; /* could be compressed */ 63 /* 64 * [edit] 65 * 66 * Put here all state variable needed during the encryption process. 67 */ 68 } ECRYPT_ctx; 69 70 /* ------------------------------------------------------------------------- */ 71 72 /* Mandatory functions */ 73 74 /* 75 * Key and message independent initialization. This function will be 76 * called once when the program starts (e.g., to build expanded S-box 77 * tables). 78 */ 79 void ECRYPT_init(void); 80 81 /* 82 * Key setup. It is the user's responsibility to select the values of 83 * keysize and ivsize from the set of supported values specified 84 * above. 85 */ 86 void ECRYPT_keysetup( 87 ECRYPT_ctx* ctx, 88 const u8* key, 89 u32 keysize, /* Key size in bits. */ 90 u32 ivsize); /* IV size in bits. */ 91 92 /* 93 * IV setup. After having called ECRYPT_keysetup(), the user is 94 * allowed to call ECRYPT_ivsetup() different times in order to 95 * encrypt/decrypt different messages with the same key but different 96 * IV's. 97 */ 98 void ECRYPT_ivsetup( 99 ECRYPT_ctx* ctx, 100 const u8* iv); 101 102 /* 103 * Encryption/decryption of arbitrary length messages. 104 * 105 * For efficiency reasons, the API provides two types of 106 * encrypt/decrypt functions. The ECRYPT_encrypt_bytes() function 107 * (declared here) encrypts byte strings of arbitrary length, while 108 * the ECRYPT_encrypt_blocks() function (defined later) only accepts 109 * lengths which are multiples of ECRYPT_BLOCKLENGTH. 110 * 111 * The user is allowed to make multiple calls to 112 * ECRYPT_encrypt_blocks() to incrementally encrypt a long message, 113 * but he is NOT allowed to make additional encryption calls once he 114 * has called ECRYPT_encrypt_bytes() (unless he starts a new message 115 * of course). For example, this sequence of calls is acceptable: 116 * 117 * ECRYPT_keysetup(); 118 * 119 * ECRYPT_ivsetup(); 120 * ECRYPT_encrypt_blocks(); 121 * ECRYPT_encrypt_blocks(); 122 * ECRYPT_encrypt_bytes(); 123 * 124 * ECRYPT_ivsetup(); 125 * ECRYPT_encrypt_blocks(); 126 * ECRYPT_encrypt_blocks(); 127 * 128 * ECRYPT_ivsetup(); 129 * ECRYPT_encrypt_bytes(); 130 * 131 * The following sequence is not: 132 * 133 * ECRYPT_keysetup(); 134 * ECRYPT_ivsetup(); 135 * ECRYPT_encrypt_blocks(); 136 * ECRYPT_encrypt_bytes(); 137 * ECRYPT_encrypt_blocks(); 138 */ 139 140 void ECRYPT_encrypt_bytes( 141 ECRYPT_ctx* ctx, 142 const u8* plaintext, 143 u8* ciphertext, 144 u32 msglen); /* Message length in bytes. */ 145 146 void ECRYPT_decrypt_bytes( 147 ECRYPT_ctx* ctx, 148 const u8* ciphertext, 149 u8* plaintext, 150 u32 msglen); /* Message length in bytes. */ 151 152 /* ------------------------------------------------------------------------- */ 153 154 /* Optional features */ 155 156 /* 157 * For testing purposes it can sometimes be useful to have a function 158 * which immediately generates keystream without having to provide it 159 * with a zero plaintext. If your cipher cannot provide this function 160 * (e.g., because it is not strictly a synchronous cipher), please 161 * reset the ECRYPT_GENERATES_KEYSTREAM flag. 162 */ 163 164 #define ECRYPT_GENERATES_KEYSTREAM 165 #ifdef ECRYPT_GENERATES_KEYSTREAM 166 167 void ECRYPT_keystream_bytes( 168 ECRYPT_ctx* ctx, 169 u8* keystream, 170 u32 length); /* Length of keystream in bytes. */ 171 172 #endif 173 174 /* ------------------------------------------------------------------------- */ 175 176 /* Optional optimizations */ 177 178 /* 179 * By default, the functions in this section are implemented using 180 * calls to functions declared above. However, you might want to 181 * implement them differently for performance reasons. 182 */ 183 184 /* 185 * All-in-one encryption/decryption of (short) packets. 186 * 187 * The default definitions of these functions can be found in 188 * "ecrypt-sync.c". If you want to implement them differently, please 189 * undef the ECRYPT_USES_DEFAULT_ALL_IN_ONE flag. 190 */ 191 #define ECRYPT_USES_DEFAULT_ALL_IN_ONE /* [edit] */ 192 193 void ECRYPT_encrypt_packet( 194 ECRYPT_ctx* ctx, 195 const u8* iv, 196 const u8* plaintext, 197 u8* ciphertext, 198 u32 msglen); 199 200 void ECRYPT_decrypt_packet( 201 ECRYPT_ctx* ctx, 202 const u8* iv, 203 const u8* ciphertext, 204 u8* plaintext, 205 u32 msglen); 206 207 /* 208 * Encryption/decryption of blocks. 209 * 210 * By default, these functions are defined as macros. If you want to 211 * provide a different implementation, please undef the 212 * ECRYPT_USES_DEFAULT_BLOCK_MACROS flag and implement the functions 213 * declared below. 214 */ 215 216 #define ECRYPT_BLOCKLENGTH 64 /* [edit] */ 217 218 #define ECRYPT_USES_DEFAULT_BLOCK_MACROS /* [edit] */ 219 #ifdef ECRYPT_USES_DEFAULT_BLOCK_MACROS 220 221 #define ECRYPT_encrypt_blocks(ctx, plaintext, ciphertext, blocks) \ 222 ECRYPT_encrypt_bytes(ctx, plaintext, ciphertext, \ 223 (blocks) * ECRYPT_BLOCKLENGTH) 224 225 #define ECRYPT_decrypt_blocks(ctx, ciphertext, plaintext, blocks) \ 226 ECRYPT_decrypt_bytes(ctx, ciphertext, plaintext, \ 227 (blocks) * ECRYPT_BLOCKLENGTH) 228 229 #ifdef ECRYPT_GENERATES_KEYSTREAM 230 231 #define ECRYPT_keystream_blocks(ctx, keystream, blocks) \ 232 ECRYPT_keystream_bytes(ctx, keystream, \ 233 (blocks) * ECRYPT_BLOCKLENGTH) 234 235 #endif 236 237 #else 238 239 void ECRYPT_encrypt_blocks( 240 ECRYPT_ctx* ctx, 241 const u8* plaintext, 242 u8* ciphertext, 243 u32 blocks); /* Message length in blocks. */ 244 245 void ECRYPT_decrypt_blocks( 246 ECRYPT_ctx* ctx, 247 const u8* ciphertext, 248 u8* plaintext, 249 u32 blocks); /* Message length in blocks. */ 250 251 #ifdef ECRYPT_GENERATES_KEYSTREAM 252 253 void ECRYPT_keystream_blocks( 254 ECRYPT_ctx* ctx, 255 const u8* keystream, 256 u32 blocks); /* Keystream length in blocks. */ 257 258 #endif 259 260 #endif 261 262 /* 263 * If your cipher can be implemented in different ways, you can use 264 * the ECRYPT_VARIANT parameter to allow the user to choose between 265 * them at compile time (e.g., gcc -DECRYPT_VARIANT=3 ...). Please 266 * only use this possibility if you really think it could make a 267 * significant difference and keep the number of variants 268 * (ECRYPT_MAXVARIANT) as small as possible (definitely not more than 269 * 10). Note also that all variants should have exactly the same 270 * external interface (i.e., the same ECRYPT_BLOCKLENGTH, etc.). 271 */ 272 #define ECRYPT_MAXVARIANT 1 /* [edit] */ 273 274 #ifndef ECRYPT_VARIANT 275 #define ECRYPT_VARIANT 1 276 #endif 277 278 #if (ECRYPT_VARIANT > ECRYPT_MAXVARIANT) 279 #error this variant does not exist 280 #endif 281 282 /* ------------------------------------------------------------------------- */ 283 284 #endif 285
