X-Git-Url: https://code.wpia.club/?a=blobdiff_plain;f=lib%2Fopenssl%2Fdoc%2Fcrypto%2FEVP_DigestInit.pod;fp=lib%2Fopenssl%2Fdoc%2Fcrypto%2FEVP_DigestInit.pod;h=ac526bb6dbcb71a597bf9d2ff54b113fd8a3df57;hb=9ff1530871deeb0f7eaa35ca0db6630724045e4a;hp=0000000000000000000000000000000000000000;hpb=25b73076b01ae059da1a2e9a1677e00788ada620;p=cassiopeia.git diff --git a/lib/openssl/doc/crypto/EVP_DigestInit.pod b/lib/openssl/doc/crypto/EVP_DigestInit.pod new file mode 100644 index 0000000..ac526bb --- /dev/null +++ b/lib/openssl/doc/crypto/EVP_DigestInit.pod @@ -0,0 +1,282 @@ +=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_sha224, EVP_sha256, +EVP_sha384, EVP_sha512, 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 64 /* SHA512 */ + + int EVP_MD_type(const EVP_MD *md); + int EVP_MD_pkey_type(const EVP_MD *md); + int EVP_MD_size(const EVP_MD *md); + int EVP_MD_block_size(const EVP_MD *md); + + const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx); + #define EVP_MD_CTX_size(e) EVP_MD_size(EVP_MD_CTX_md(e)) + #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_sha224(void); + const EVP_MD *EVP_sha256(void); + const EVP_MD *EVP_sha384(void); + const EVP_MD *EVP_sha512(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 context B. + +EVP_MD_CTX_create() allocates, initializes and returns a digest context. + +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 +context 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. Since digests and signature algorithms +are no longer linked this function is only retained for compatibility +reasons. + +EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_sha224(), EVP_sha256(), +EVP_sha384(), EVP_sha512(), EVP_mdc2() and EVP_ripemd160() return B +structures for the MD2, MD5, SHA, SHA1, SHA224, SHA256, SHA384, SHA512, MDC2 +and RIPEMD160 digest algorithms respectively. + +EVP_dss() and EVP_dss1() return B structures for SHA and SHA1 digest +algorithms but using DSS (DSA) for the signature algorithm. Note: there is +no need to use these pseudo-digests in OpenSSL 1.0.0 and later, they are +however retained for compatibility. + +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() and +EVP_MD_CTX_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. + +New applications should use the SHA2 digest algorithms such as SHA256. +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. + +Stack allocation of EVP_MD_CTX structures is common, for example: + + EVP_MD_CTX mctx; + EVP_MD_CTX_init(&mctx); + +This will cause binary compatibility issues if the size of EVP_MD_CTX +structure changes (this will only happen with a major release of OpenSSL). +Applications wishing to avoid this should use EVP_MD_CTX_create() instead: + + EVP_MD_CTX *mctx; + mctx = EVP_MD_CTX_create(); + + +=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); + } + + mdctx = EVP_MD_CTX_create(); + 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_destroy(mdctx); + + printf("Digest is: "); + for(i = 0; i < md_len; i++) + printf("%02x", md_value[i]); + printf("\n"); + + /* Call this once before exit. */ + EVP_cleanup(); + exit(0); + } + +=head1 SEE ALSO + +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. + +The link between digests and signing algorithms was fixed in OpenSSL 1.0 and +later, so now EVP_sha1() can be used with RSA and DSA; there is no need to +use EVP_dss1() any more. + +OpenSSL 1.0 and later does not include the MD2 digest algorithm in the +default configuration due to its security weaknesses. + +=cut