BIO_f_md, BIO_set_md, BIO_get_md, BIO_get_md_ctx - message digest BIO filter
+=for comment multiple includes
+
=head1 SYNOPSIS
#include <openssl/bio.h>
#include <openssl/evp.h>
- BIO_METHOD * BIO_f_md(void);
- int BIO_set_md(BIO *b,EVP_MD *md);
- int BIO_get_md(BIO *b,EVP_MD **mdp);
- int BIO_get_md_ctx(BIO *b,EVP_MD_CTX **mdcp);
+ const BIO_METHOD *BIO_f_md(void);
+ int BIO_set_md(BIO *b, EVP_MD *md);
+ int BIO_get_md(BIO *b, EVP_MD **mdp);
+ int BIO_get_md_ctx(BIO *b, EVP_MD_CTX **mdcp);
=head1 DESCRIPTION
a chain containing digest BIOs then this can be done by prepending
a buffering BIO.
-Before OpenSSL 1.0.0 the call to BIO_get_md_ctx() would only work if the BIO
-had been initialized for example by calling BIO_set_md() ). In OpenSSL
-1.0.0 and later the context is always returned and the BIO is state is set
-to initialized. This allows applications to initialize the context externally
+Calling BIO_get_md_ctx() will return the context and initialize the BIO
+state. This allows applications to initialize the context externally
if the standard calls such as BIO_set_md() are not sufficiently flexible.
=head1 RETURN VALUES
BIO_set_md(mdtmp, EVP_md5());
bio = BIO_push(mdtmp, bio);
do {
- rdlen = BIO_read(bio, buf, sizeof(buf));
+ rdlen = BIO_read(bio, buf, sizeof(buf));
/* Might want to do something with the data here */
- } while(rdlen > 0);
+ } while (rdlen > 0);
This next example retrieves the message digests from a BIO chain and
outputs them. This could be used with the examples above.
unsigned char mdbuf[EVP_MAX_MD_SIZE];
int mdlen;
int i;
- mdtmp = bio; /* Assume bio has previously been set up */
+ mdtmp = bio; /* Assume bio has previously been set up */
do {
- EVP_MD *md;
- mdtmp = BIO_find_type(mdtmp, BIO_TYPE_MD);
- if(!mdtmp) break;
- BIO_get_md(mdtmp, &md);
+ EVP_MD *md;
+ mdtmp = BIO_find_type(mdtmp, BIO_TYPE_MD);
+ if (!mdtmp) break;
+ BIO_get_md(mdtmp, &md);
printf("%s digest", OBJ_nid2sn(EVP_MD_type(md)));
- mdlen = BIO_gets(mdtmp, mdbuf, EVP_MAX_MD_SIZE);
- for(i = 0; i < mdlen; i++) printf(":%02X", mdbuf[i]);
- printf("\n");
- mdtmp = BIO_next(mdtmp);
- } while(mdtmp);
+ mdlen = BIO_gets(mdtmp, mdbuf, EVP_MAX_MD_SIZE);
+ for (i = 0; i < mdlen; i++) printf(":%02X", mdbuf[i]);
+ printf("\n");
+ mdtmp = BIO_next(mdtmp);
+ } while (mdtmp);
BIO_free_all(bio);
the data passed through and that digests should be retrieved using a
separate BIO_ctrl() call.
-=head1 SEE ALSO
+=head1 HISTORY
+
+Before OpenSSL 1.0.0., the call to BIO_get_md_ctx() would only work if the
+BIO was initialized first.
+
+=head1 COPYRIGHT
+
+Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the OpenSSL license (the "License"). You may not use
+this file except in compliance with the License. You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
-TBA
+=cut