=pod =head1 NAME EVP_MD_CTX_init, EVP_MD_CTX_create, EVP_DigestInit_ex, EVP_DigestUpdate, EVP_DigestFinal_ex, EVP_MD_CTX_cleanup, EVP_MD_CTX_destroy, EVP_MAX_MD_SIZE, EVP_MD_CTX_copy_ex, EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size, EVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size, EVP_MD_CTX_block_size, EVP_MD_CTX_type, EVP_md_null, EVP_md2, EVP_md5, EVP_sha, EVP_sha1, EVP_dss, EVP_dss1, EVP_mdc2, EVP_ripemd160, EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj - EVP digest routines =head1 SYNOPSIS #include void EVP_MD_CTX_init(EVP_MD_CTX *ctx); EVP_MD_CTX *EVP_MD_CTX_create(void); int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl); int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt); int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s); int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx); void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx); int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out,const EVP_MD_CTX *in); int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type); int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s); int EVP_MD_CTX_copy(EVP_MD_CTX *out,EVP_MD_CTX *in); #define EVP_MAX_MD_SIZE (16+20) /* The SSLv3 md5+sha1 type */ #define EVP_MD_type(e) ((e)->type) #define EVP_MD_pkey_type(e) ((e)->pkey_type) #define EVP_MD_size(e) ((e)->md_size) #define EVP_MD_block_size(e) ((e)->block_size) #define EVP_MD_CTX_md(e) (e)->digest) #define EVP_MD_CTX_size(e) EVP_MD_size((e)->digest) #define EVP_MD_CTX_block_size(e) EVP_MD_block_size((e)->digest) #define EVP_MD_CTX_type(e) EVP_MD_type((e)->digest) const EVP_MD *EVP_md_null(void); const EVP_MD *EVP_md2(void); const EVP_MD *EVP_md5(void); const EVP_MD *EVP_sha(void); const EVP_MD *EVP_sha1(void); const EVP_MD *EVP_dss(void); const EVP_MD *EVP_dss1(void); const EVP_MD *EVP_mdc2(void); const EVP_MD *EVP_ripemd160(void); const EVP_MD *EVP_get_digestbyname(const char *name); #define EVP_get_digestbynid(a) EVP_get_digestbyname(OBJ_nid2sn(a)) #define EVP_get_digestbyobj(a) EVP_get_digestbynid(OBJ_obj2nid(a)) =head1 DESCRIPTION The EVP digest routines are a high level interface to message digests. EVP_MD_CTX_init() initializes digest contet B. EVP_MD_CTX_create() allocates, initializes and returns a digest contet. EVP_DigestInit_ex() sets up digest context B to use a digest B from ENGINE B. B must be initialized before calling this function. B will typically be supplied by a functionsuch as EVP_sha1(). If B is NULL then the default implementation of digest B is used. EVP_DigestUpdate() hashes B bytes of data at B into the digest context B. This function can be called several times on the same B to hash additional data. EVP_DigestFinal_ex() retrieves the digest value from B and places it in B. If the B parameter is not NULL then the number of bytes of data written (i.e. the length of the digest) will be written to the integer at B, at most B bytes will be written. After calling EVP_DigestFinal_ex() no additional calls to EVP_DigestUpdate() can be made, but EVP_DigestInit_ex() can be called to initialize a new digest operation. EVP_MD_CTX_cleanup() cleans up digest context B, it should be called after a digest context is no longer needed. EVP_MD_CTX_destroy() cleans up digest context B and frees up the space allocated to it, it should be called only on a context created using EVP_MD_CTX_create(). EVP_MD_CTX_copy_ex() can be used to copy the message digest state from B to B. This is useful if large amounts of data are to be hashed which only differ in the last few bytes. B must be initialized before calling this function. EVP_DigestInit() behaves in the same way as EVP_DigestInit_ex() except the passed context B does not have to be initialized, and it always uses the default digest implementation. EVP_DigestFinal() is similar to EVP_DigestFinal_ex() except the digest contet B is automatically cleaned up. EVP_MD_CTX_copy() is similar to EVP_MD_CTX_copy_ex() except the destination B does not have to be initialized. EVP_MD_size() and EVP_MD_CTX_size() return the size of the message digest when passed an B or an B structure, i.e. the size of the hash. EVP_MD_block_size() and EVP_MD_CTX_block_size() return the block size of the message digest when passed an B or an B structure. EVP_MD_type() and EVP_MD_CTX_type() return the NID of the OBJECT IDENTIFIER representing the given message digest when passed an B structure. For example EVP_MD_type(EVP_sha1()) returns B. This function is normally used when setting ASN1 OIDs. EVP_MD_CTX_md() returns the B structure corresponding to the passed B. EVP_MD_pkey_type() returns the NID of the public key signing algorithm associated with this digest. For example EVP_sha1() is associated with RSA so this will return B. This "link" between digests and signature algorithms may not be retained in future versions of OpenSSL. EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_mdc2() and EVP_ripemd160() return B structures for the MD2, MD5, SHA, SHA1, MDC2 and RIPEMD160 digest algorithms respectively. The associated signature algorithm is RSA in each case. EVP_dss() and EVP_dss1() return B structures for SHA and SHA1 digest algorithms but using DSS (DSA) for the signature algorithm. EVP_md_null() is a "null" message digest that does nothing: i.e. the hash it returns is of zero length. EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj() return an B structure when passed a digest name, a digest NID or an ASN1_OBJECT structure respectively. The digest table must be initialized using, for example, OpenSSL_add_all_digests() for these functions to work. =head1 RETURN VALUES EVP_DigestInit_ex(), EVP_DigestUpdate() and EVP_DigestFinal_ex() return 1 for success and 0 for failure. EVP_MD_CTX_copy_ex() returns 1 if successful or 0 for failure. EVP_MD_type(), EVP_MD_pkey_type() and EVP_MD_type() return the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none exists. EVP_MD_size(), EVP_MD_block_size(), EVP_MD_CTX_size(e), EVP_MD_size(), EVP_MD_CTX_block_size() and EVP_MD_block_size() return the digest or block size in bytes. EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_dss(), EVP_dss1(), EVP_mdc2() and EVP_ripemd160() return pointers to the corresponding EVP_MD structures. EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj() return either an B structure or NULL if an error occurs. =head1 NOTES The B interface to message digests should almost always be used in preference to the low level interfaces. This is because the code then becomes transparent to the digest used and much more flexible. SHA1 is the digest of choice for new applications. The other digest algorithms are still in common use. For most applications the B parameter to EVP_DigestInit_ex() will be set to NULL to use the default digest implementation. The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are obsolete but are retained to maintain compatibility with existing code. New applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context instead of initializing and cleaning it up on each call and allow non default implementations of digests to be specified. In OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use memory leaks will occur. =head1 EXAMPLE This example digests the data "Test Message\n" and "Hello World\n", using the digest name passed on the command line. #include #include main(int argc, char *argv[]) { EVP_MD_CTX mdctx; const EVP_MD *md; char mess1[] = "Test Message\n"; char mess2[] = "Hello World\n"; unsigned char md_value[EVP_MAX_MD_SIZE]; int md_len, i; OpenSSL_add_all_digests(); if(!argv[1]) { printf("Usage: mdtest digestname\n"); exit(1); } md = EVP_get_digestbyname(argv[1]); if(!md) { printf("Unknown message digest %s\n", argv[1]); exit(1); } EVP_MD_CTX_init(&mdctx); EVP_DigestInit_ex(&mdctx, md, NULL); EVP_DigestUpdate(&mdctx, mess1, strlen(mess1)); EVP_DigestUpdate(&mdctx, mess2, strlen(mess2)); EVP_DigestFinal_ex(&mdctx, md_value, &md_len); EVP_MD_CTX_cleanup(&mdctx); printf("Digest is: "); for(i = 0; i < md_len; i++) printf("%02x", md_value[i]); printf("\n"); } =head1 BUGS The link between digests and signing algorithms results in a situation where EVP_sha1() must be used with RSA and EVP_dss1() must be used with DSS even though they are identical digests. =head1 SEE ALSO L, L, L, L, L, L, L, L =head1 HISTORY EVP_DigestInit(), EVP_DigestUpdate() and EVP_DigestFinal() are available in all versions of SSLeay and OpenSSL. EVP_MD_CTX_init(), EVP_MD_CTX_create(), EVP_MD_CTX_copy_ex(), EVP_MD_CTX_cleanup(), EVP_MD_CTX_destroy(), EVP_DigestInit_ex() and EVP_DigestFinal_ex() were added in OpenSSL 0.9.7. EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_dss(), EVP_dss1(), EVP_mdc2() and EVP_ripemd160() were changed to return truely const EVP_MD * in OpenSSL 0.9.7. =cut 194' href='#n194'>194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431