EVP_DigestInit.pod revision 238405
18876Srgrimes=pod 24Srgrimes 34Srgrimes=head1 NAME 44Srgrimes 58876SrgrimesEVP_MD_CTX_init, EVP_MD_CTX_create, EVP_DigestInit_ex, EVP_DigestUpdate, 64SrgrimesEVP_DigestFinal_ex, EVP_MD_CTX_cleanup, EVP_MD_CTX_destroy, EVP_MAX_MD_SIZE, 74SrgrimesEVP_MD_CTX_copy_ex, EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size, 84SrgrimesEVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size, EVP_MD_CTX_block_size, EVP_MD_CTX_type, 94SrgrimesEVP_md_null, EVP_md2, EVP_md5, EVP_sha, EVP_sha1, EVP_sha224, EVP_sha256, 104SrgrimesEVP_sha384, EVP_sha512, EVP_dss, EVP_dss1, EVP_mdc2, 118876SrgrimesEVP_ripemd160, EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj - 128876SrgrimesEVP digest routines 134Srgrimes 144Srgrimes=head1 SYNOPSIS 158876Srgrimes 164Srgrimes #include <openssl/evp.h> 178876Srgrimes 184Srgrimes void EVP_MD_CTX_init(EVP_MD_CTX *ctx); 194Srgrimes EVP_MD_CTX *EVP_MD_CTX_create(void); 204Srgrimes 214Srgrimes int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl); 228876Srgrimes int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt); 234Srgrimes int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, 244Srgrimes unsigned int *s); 254Srgrimes 2617495Sjoerg int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx); 274Srgrimes void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx); 28623Srgrimes 294Srgrimes int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out,const EVP_MD_CTX *in); 304Srgrimes 314Srgrimes int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type); 324Srgrimes int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, 334Srgrimes unsigned int *s); 342056Swollman 3517495Sjoerg int EVP_MD_CTX_copy(EVP_MD_CTX *out,EVP_MD_CTX *in); 362056Swollman 3712734Sbde #define EVP_MAX_MD_SIZE 64 /* SHA512 */ 3812734Sbde 3912734Sbde int EVP_MD_type(const EVP_MD *md); 402056Swollman int EVP_MD_pkey_type(const EVP_MD *md); 412056Swollman int EVP_MD_size(const EVP_MD *md); 424Srgrimes int EVP_MD_block_size(const EVP_MD *md); 434Srgrimes 444Srgrimes const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx); 454Srgrimes #define EVP_MD_CTX_size(e) EVP_MD_size(EVP_MD_CTX_md(e)) 464Srgrimes #define EVP_MD_CTX_block_size(e) EVP_MD_block_size((e)->digest) 474Srgrimes #define EVP_MD_CTX_type(e) EVP_MD_type((e)->digest) 484Srgrimes 494Srgrimes const EVP_MD *EVP_md_null(void); 504Srgrimes const EVP_MD *EVP_md2(void); 514Srgrimes const EVP_MD *EVP_md5(void); 5212720Sphk const EVP_MD *EVP_sha(void); 5312720Sphk const EVP_MD *EVP_sha1(void); 5412720Sphk const EVP_MD *EVP_dss(void); 5512720Sphk const EVP_MD *EVP_dss1(void); 564Srgrimes const EVP_MD *EVP_mdc2(void); 5717495Sjoerg const EVP_MD *EVP_ripemd160(void); 5817495Sjoerg 5917495Sjoerg const EVP_MD *EVP_sha224(void); 6017495Sjoerg const EVP_MD *EVP_sha256(void); 6117495Sjoerg const EVP_MD *EVP_sha384(void); 6217495Sjoerg const EVP_MD *EVP_sha512(void); 6317495Sjoerg 644Srgrimes const EVP_MD *EVP_get_digestbyname(const char *name); 654Srgrimes #define EVP_get_digestbynid(a) EVP_get_digestbyname(OBJ_nid2sn(a)) 664Srgrimes #define EVP_get_digestbyobj(a) EVP_get_digestbynid(OBJ_obj2nid(a)) 674Srgrimes 684Srgrimes=head1 DESCRIPTION 6912515Sphk 7012515SphkThe EVP digest routines are a high level interface to message digests. 7112515Sphk 7212515SphkEVP_MD_CTX_init() initializes digest context B<ctx>. 7312515Sphk 7412473SbdeEVP_MD_CTX_create() allocates, initializes and returns a digest context. 754Srgrimes 764SrgrimesEVP_DigestInit_ex() sets up digest context B<ctx> to use a digest 774SrgrimesB<type> from ENGINE B<impl>. B<ctx> must be initialized before calling this 784Srgrimesfunction. B<type> will typically be supplied by a functionsuch as EVP_sha1(). 794SrgrimesIf B<impl> is NULL then the default implementation of digest B<type> is used. 804Srgrimes 814SrgrimesEVP_DigestUpdate() hashes B<cnt> bytes of data at B<d> into the 824Srgrimesdigest context B<ctx>. This function can be called several times on the 834Srgrimessame B<ctx> to hash additional data. 844Srgrimes 854SrgrimesEVP_DigestFinal_ex() retrieves the digest value from B<ctx> and places 864Srgrimesit in B<md>. If the B<s> parameter is not NULL then the number of 874Srgrimesbytes of data written (i.e. the length of the digest) will be written 884Srgrimesto the integer at B<s>, at most B<EVP_MAX_MD_SIZE> bytes will be written. 894SrgrimesAfter calling EVP_DigestFinal_ex() no additional calls to EVP_DigestUpdate() 904Srgrimescan be made, but EVP_DigestInit_ex() can be called to initialize a new 914Srgrimesdigest operation. 924Srgrimes 934SrgrimesEVP_MD_CTX_cleanup() cleans up digest context B<ctx>, it should be called 944Srgrimesafter a digest context is no longer needed. 954Srgrimes 964SrgrimesEVP_MD_CTX_destroy() cleans up digest context B<ctx> and frees up the 974Srgrimesspace allocated to it, it should be called only on a context created 984Srgrimesusing EVP_MD_CTX_create(). 994Srgrimes 1004SrgrimesEVP_MD_CTX_copy_ex() can be used to copy the message digest state from 1014SrgrimesB<in> to B<out>. This is useful if large amounts of data are to be 1024Srgrimeshashed which only differ in the last few bytes. B<out> must be initialized 1034Srgrimesbefore calling this function. 1044Srgrimes 1054SrgrimesEVP_DigestInit() behaves in the same way as EVP_DigestInit_ex() except 1064Srgrimesthe passed context B<ctx> does not have to be initialized, and it always 1074Srgrimesuses the default digest implementation. 1084Srgrimes 1094SrgrimesEVP_DigestFinal() is similar to EVP_DigestFinal_ex() except the digest 1104Srgrimescontext B<ctx> is automatically cleaned up. 1114Srgrimes 1124SrgrimesEVP_MD_CTX_copy() is similar to EVP_MD_CTX_copy_ex() except the destination 1134SrgrimesB<out> does not have to be initialized. 1144Srgrimes 1154SrgrimesEVP_MD_size() and EVP_MD_CTX_size() return the size of the message digest 1164Srgrimeswhen passed an B<EVP_MD> or an B<EVP_MD_CTX> structure, i.e. the size of the 1174Srgrimeshash. 1184Srgrimes 1194SrgrimesEVP_MD_block_size() and EVP_MD_CTX_block_size() return the block size of the 1204Srgrimesmessage digest when passed an B<EVP_MD> or an B<EVP_MD_CTX> structure. 1214Srgrimes 1224SrgrimesEVP_MD_type() and EVP_MD_CTX_type() return the NID of the OBJECT IDENTIFIER 1234Srgrimesrepresenting the given message digest when passed an B<EVP_MD> structure. 1244SrgrimesFor example EVP_MD_type(EVP_sha1()) returns B<NID_sha1>. This function is 1254Srgrimesnormally used when setting ASN1 OIDs. 1264Srgrimes 1274SrgrimesEVP_MD_CTX_md() returns the B<EVP_MD> structure corresponding to the passed 1284SrgrimesB<EVP_MD_CTX>. 1294Srgrimes 1304SrgrimesEVP_MD_pkey_type() returns the NID of the public key signing algorithm associated 1314Srgrimeswith this digest. For example EVP_sha1() is associated with RSA so this will 1324Srgrimesreturn B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms 1334Srgrimesare no longer linked this function is only retained for compatibility 1344Srgrimesreasons. 1354Srgrimes 1364SrgrimesEVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_sha224(), EVP_sha256(), 1374SrgrimesEVP_sha384(), EVP_sha512(), EVP_mdc2() and EVP_ripemd160() return B<EVP_MD> 1384Srgrimesstructures for the MD2, MD5, SHA, SHA1, SHA224, SHA256, SHA384, SHA512, MDC2 1394Srgrimesand RIPEMD160 digest algorithms respectively. 1404Srgrimes 1414SrgrimesEVP_dss() and EVP_dss1() return B<EVP_MD> structures for SHA and SHA1 digest 1424Srgrimesalgorithms but using DSS (DSA) for the signature algorithm. Note: there is 1434Srgrimesno need to use these pseudo-digests in OpenSSL 1.0.0 and later, they are 1444Srgrimeshowever retained for compatibility. 1454Srgrimes 1464SrgrimesEVP_md_null() is a "null" message digest that does nothing: i.e. the hash it 1474Srgrimesreturns is of zero length. 1484Srgrimes 1494SrgrimesEVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj() 1504Srgrimesreturn an B<EVP_MD> structure when passed a digest name, a digest NID or 1514Srgrimesan ASN1_OBJECT structure respectively. The digest table must be initialized 1524Srgrimesusing, for example, OpenSSL_add_all_digests() for these functions to work. 1534Srgrimes 1544Srgrimes=head1 RETURN VALUES 1554Srgrimes 1564SrgrimesEVP_DigestInit_ex(), EVP_DigestUpdate() and EVP_DigestFinal_ex() return 1 for 1574Srgrimessuccess and 0 for failure. 1584Srgrimes 1594SrgrimesEVP_MD_CTX_copy_ex() returns 1 if successful or 0 for failure. 1604Srgrimes 1614SrgrimesEVP_MD_type(), EVP_MD_pkey_type() and EVP_MD_type() return the NID of the 1624Srgrimescorresponding OBJECT IDENTIFIER or NID_undef if none exists. 1634Srgrimes 1644SrgrimesEVP_MD_size(), EVP_MD_block_size(), EVP_MD_CTX_size(e), EVP_MD_size(), 1654SrgrimesEVP_MD_CTX_block_size() and EVP_MD_block_size() return the digest or block 1664Srgrimessize in bytes. 1674Srgrimes 1684SrgrimesEVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_dss(), 1694SrgrimesEVP_dss1(), EVP_mdc2() and EVP_ripemd160() return pointers to the 1704Srgrimescorresponding EVP_MD structures. 1714Srgrimes 1724SrgrimesEVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj() 1734Srgrimesreturn either an B<EVP_MD> structure or NULL if an error occurs. 1744Srgrimes 1754Srgrimes=head1 NOTES 1764Srgrimes 1774SrgrimesThe B<EVP> interface to message digests should almost always be used in 1784Srgrimespreference to the low level interfaces. This is because the code then becomes 1794Srgrimestransparent to the digest used and much more flexible. 1804Srgrimes 1814SrgrimesNew applications should use the SHA2 digest algorithms such as SHA256. 18217495SjoergThe other digest algorithms are still in common use. 1834Srgrimes 1844SrgrimesFor most applications the B<impl> parameter to EVP_DigestInit_ex() will be 1854Srgrimesset to NULL to use the default digest implementation. 1864Srgrimes 1874SrgrimesThe functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are 18817495Sjoergobsolete but are retained to maintain compatibility with existing code. New 18917495Sjoergapplications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and 19017495SjoergEVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context 19117495Sjoerginstead of initializing and cleaning it up on each call and allow non default 19217495Sjoergimplementations of digests to be specified. 19317495Sjoerg 19417495SjoergIn OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use 19517495Sjoergmemory leaks will occur. 19617495Sjoerg 19717495SjoergStack allocation of EVP_MD_CTX structures is common, for example: 19817495Sjoerg 19917495Sjoerg EVP_MD_CTX mctx; 20017495Sjoerg EVP_MD_CTX_init(&mctx); 20117495Sjoerg 20217495SjoergThis will cause binary compatibility issues if the size of EVP_MD_CTX 20317495Sjoergstructure changes (this will only happen with a major release of OpenSSL). 20417495SjoergApplications wishing to avoid this should use EVP_MD_CTX_create() instead: 20517495Sjoerg 20617495Sjoerg EVP_MD_CTX *mctx; 20717495Sjoerg mctx = EVP_MD_CTX_create(); 20817495Sjoerg 20917495Sjoerg 21017495Sjoerg=head1 EXAMPLE 21117495Sjoerg 21217495SjoergThis example digests the data "Test Message\n" and "Hello World\n", using the 21317495Sjoergdigest name passed on the command line. 21417495Sjoerg 21517495Sjoerg #include <stdio.h> 21617495Sjoerg #include <openssl/evp.h> 21717495Sjoerg 21817495Sjoerg main(int argc, char *argv[]) 21917495Sjoerg { 22017495Sjoerg EVP_MD_CTX *mdctx; 22117495Sjoerg const EVP_MD *md; 2224Srgrimes char mess1[] = "Test Message\n"; 2234Srgrimes char mess2[] = "Hello World\n"; 2244Srgrimes unsigned char md_value[EVP_MAX_MD_SIZE]; 2254Srgrimes int md_len, i; 2264Srgrimes 2274Srgrimes OpenSSL_add_all_digests(); 2284Srgrimes 2294Srgrimes if(!argv[1]) { 2304Srgrimes printf("Usage: mdtest digestname\n"); 2314Srgrimes exit(1); 2324Srgrimes } 2334Srgrimes 2344Srgrimes md = EVP_get_digestbyname(argv[1]); 2354Srgrimes 2364Srgrimes if(!md) { 2374Srgrimes printf("Unknown message digest %s\n", argv[1]); 2384Srgrimes exit(1); 2394Srgrimes } 2404Srgrimes 2414Srgrimes mdctx = EVP_MD_CTX_create(); 2424Srgrimes EVP_DigestInit_ex(mdctx, md, NULL); 2434Srgrimes EVP_DigestUpdate(mdctx, mess1, strlen(mess1)); 2444Srgrimes EVP_DigestUpdate(mdctx, mess2, strlen(mess2)); 2454Srgrimes EVP_DigestFinal_ex(mdctx, md_value, &md_len); 2464Srgrimes EVP_MD_CTX_destroy(mdctx); 24712473Sbde 2482112Swollman printf("Digest is: "); 2492112Swollman for(i = 0; i < md_len; i++) printf("%02x", md_value[i]); 2502112Swollman printf("\n"); 2512112Swollman } 2522112Swollman 2534Srgrimes=head1 SEE ALSO 2544Srgrimes 2554SrgrimesL<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>, 2564SrgrimesL<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>, 25717495SjoergL<sha(3)|sha(3)>, L<dgst(1)|dgst(1)> 25817495Sjoerg 25917495Sjoerg=head1 HISTORY 26017495Sjoerg 26117495SjoergEVP_DigestInit(), EVP_DigestUpdate() and EVP_DigestFinal() are 26217495Sjoergavailable in all versions of SSLeay and OpenSSL. 26317495Sjoerg 26417495SjoergEVP_MD_CTX_init(), EVP_MD_CTX_create(), EVP_MD_CTX_copy_ex(), 26517495SjoergEVP_MD_CTX_cleanup(), EVP_MD_CTX_destroy(), EVP_DigestInit_ex() 26617495Sjoergand EVP_DigestFinal_ex() were added in OpenSSL 0.9.7. 26717495Sjoerg 26817495SjoergEVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), 26917495SjoergEVP_dss(), EVP_dss1(), EVP_mdc2() and EVP_ripemd160() were 27017495Sjoergchanged to return truely const EVP_MD * in OpenSSL 0.9.7. 2714Srgrimes 2724SrgrimesThe link between digests and signing algorithms was fixed in OpenSSL 1.0 and 2734Srgrimeslater, so now EVP_sha1() can be used with RSA and DSA, there is no need to 2744Srgrimesuse EVP_dss1() any more. 2754Srgrimes 2764SrgrimesOpenSSL 1.0 and later does not include the MD2 digest algorithm in the 2774Srgrimesdefault configuration due to its security weaknesses. 2784Srgrimes 2794Srgrimes=cut 2804Srgrimes