--- /dev/null
+=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 <openssl/evp.h>
+
+ 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<ctx>.
+
+EVP_MD_CTX_create() allocates, initializes and returns a digest context.
+
+EVP_DigestInit_ex() sets up digest context B<ctx> to use a digest
+B<type> from ENGINE B<impl>. B<ctx> must be initialized before calling this
+function. B<type> will typically be supplied by a functionsuch as EVP_sha1().
+If B<impl> is NULL then the default implementation of digest B<type> is used.
+
+EVP_DigestUpdate() hashes B<cnt> bytes of data at B<d> into the
+digest context B<ctx>. This function can be called several times on the
+same B<ctx> to hash additional data.
+
+EVP_DigestFinal_ex() retrieves the digest value from B<ctx> and places
+it in B<md>. If the B<s> 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<s>, at most B<EVP_MAX_MD_SIZE> 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<ctx>, it should be called
+after a digest context is no longer needed.
+
+EVP_MD_CTX_destroy() cleans up digest context B<ctx> 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<in> to B<out>. This is useful if large amounts of data are to be
+hashed which only differ in the last few bytes. B<out> must be initialized
+before calling this function.
+
+EVP_DigestInit() behaves in the same way as EVP_DigestInit_ex() except
+the passed context B<ctx> 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<ctx> is automatically cleaned up.
+
+EVP_MD_CTX_copy() is similar to EVP_MD_CTX_copy_ex() except the destination
+B<out> 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<EVP_MD> or an B<EVP_MD_CTX> 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<EVP_MD> or an B<EVP_MD_CTX> 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<EVP_MD> structure.
+For example EVP_MD_type(EVP_sha1()) returns B<NID_sha1>. This function is
+normally used when setting ASN1 OIDs.
+
+EVP_MD_CTX_md() returns the B<EVP_MD> structure corresponding to the passed
+B<EVP_MD_CTX>.
+
+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<NID_sha1WithRSAEncryption>. 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<EVP_MD>
+structures for the MD2, MD5, SHA, SHA1, SHA224, SHA256, SHA384, SHA512, MDC2
+and RIPEMD160 digest algorithms respectively.
+
+EVP_dss() and EVP_dss1() return B<EVP_MD> 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<EVP_MD> 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<EVP_MD> structure or NULL if an error occurs.
+
+=head1 NOTES
+
+The B<EVP> 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<impl> 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 <stdio.h>
+ #include <openssl/evp.h>
+
+ 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<dgst(1)|dgst(1)>,
+L<evp(3)|evp(3)>
+
+=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
projects / cassiopeia.git / blobdiff