mirror of
https://github.com/openssl/openssl.git
synced 2024-12-15 06:01:37 +08:00
5001287c0d
Reviewed-by: Shane Lontis <shane.lontis@oracle.com> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/16767)
163 lines
4.7 KiB
Plaintext
163 lines
4.7 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
BIO_f_md, BIO_set_md, BIO_get_md, BIO_get_md_ctx - message digest BIO filter
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
=for openssl multiple includes
|
|
|
|
#include <openssl/bio.h>
|
|
#include <openssl/evp.h>
|
|
|
|
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
|
|
|
|
BIO_f_md() returns the message digest BIO method. This is a filter
|
|
BIO that digests any data passed through it, it is a BIO wrapper
|
|
for the digest routines EVP_DigestInit(), EVP_DigestUpdate()
|
|
and EVP_DigestFinal().
|
|
|
|
Any data written or read through a digest BIO using BIO_read_ex() and
|
|
BIO_write_ex() is digested.
|
|
|
|
BIO_gets(), if its B<size> parameter is large enough finishes the
|
|
digest calculation and returns the digest value. BIO_puts() is
|
|
not supported.
|
|
|
|
BIO_reset() reinitialises a digest BIO.
|
|
|
|
BIO_set_md() sets the message digest of BIO B<b> to B<md>: this
|
|
must be called to initialize a digest BIO before any data is
|
|
passed through it. It is a BIO_ctrl() macro.
|
|
|
|
BIO_get_md() places the a pointer to the digest BIOs digest method
|
|
in B<mdp>, it is a BIO_ctrl() macro.
|
|
|
|
BIO_get_md_ctx() returns the digest BIOs context into B<mdcp>.
|
|
|
|
=head1 NOTES
|
|
|
|
The context returned by BIO_get_md_ctx() can be used in calls
|
|
to EVP_DigestFinal() and also the signature routines EVP_SignFinal()
|
|
and EVP_VerifyFinal().
|
|
|
|
The context returned by BIO_get_md_ctx() is an internal context
|
|
structure. Changes made to this context will affect the digest
|
|
BIO itself and the context pointer will become invalid when the digest
|
|
BIO is freed.
|
|
|
|
After the digest has been retrieved from a digest BIO it must be
|
|
reinitialized by calling BIO_reset(), or BIO_set_md() before any more
|
|
data is passed through it.
|
|
|
|
If an application needs to call BIO_gets() or BIO_puts() through
|
|
a chain containing digest BIOs then this can be done by prepending
|
|
a buffering BIO.
|
|
|
|
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_f_md() returns the digest BIO method.
|
|
|
|
BIO_set_md(), BIO_get_md() and BIO_md_ctx() return 1 for success and
|
|
<=0 for failure.
|
|
|
|
=head1 EXAMPLES
|
|
|
|
The following example creates a BIO chain containing an SHA1 and MD5
|
|
digest BIO and passes the string "Hello World" through it. Error
|
|
checking has been omitted for clarity.
|
|
|
|
BIO *bio, *mdtmp;
|
|
char message[] = "Hello World";
|
|
|
|
bio = BIO_new(BIO_s_null());
|
|
mdtmp = BIO_new(BIO_f_md());
|
|
BIO_set_md(mdtmp, EVP_sha1());
|
|
/*
|
|
* For BIO_push() we want to append the sink BIO and keep a note of
|
|
* the start of the chain.
|
|
*/
|
|
bio = BIO_push(mdtmp, bio);
|
|
mdtmp = BIO_new(BIO_f_md());
|
|
BIO_set_md(mdtmp, EVP_md5());
|
|
bio = BIO_push(mdtmp, bio);
|
|
/* Note: mdtmp can now be discarded */
|
|
BIO_write(bio, message, strlen(message));
|
|
|
|
The next example digests data by reading through a chain instead:
|
|
|
|
BIO *bio, *mdtmp;
|
|
char buf[1024];
|
|
int rdlen;
|
|
|
|
bio = BIO_new_file(file, "rb");
|
|
mdtmp = BIO_new(BIO_f_md());
|
|
BIO_set_md(mdtmp, EVP_sha1());
|
|
bio = BIO_push(mdtmp, bio);
|
|
mdtmp = BIO_new(BIO_f_md());
|
|
BIO_set_md(mdtmp, EVP_md5());
|
|
bio = BIO_push(mdtmp, bio);
|
|
do {
|
|
rdlen = BIO_read(bio, buf, sizeof(buf));
|
|
/* Might want to do something with the data here */
|
|
} 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.
|
|
|
|
BIO *mdtmp;
|
|
unsigned char mdbuf[EVP_MAX_MD_SIZE];
|
|
int mdlen;
|
|
int i;
|
|
|
|
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);
|
|
printf("%s digest", OBJ_nid2sn(EVP_MD_get_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);
|
|
|
|
BIO_free_all(bio);
|
|
|
|
=head1 BUGS
|
|
|
|
The lack of support for BIO_puts() and the non standard behaviour of
|
|
BIO_gets() could be regarded as anomalous. It could be argued that BIO_gets()
|
|
and BIO_puts() should be passed to the next BIO in the chain and digest
|
|
the data passed through and that digests should be retrieved using a
|
|
separate BIO_ctrl() call.
|
|
|
|
=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 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the Apache License 2.0 (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>.
|
|
|
|
=cut
|