b97fdb57a2
Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from https://github.com/openssl/openssl/pull/1900)
259 lines
9.1 KiB
Text
259 lines
9.1 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
EVP_MD_CTX_new, EVP_MD_CTX_reset, EVP_MD_CTX_free, EVP_MD_CTX_copy_ex,
|
|
EVP_DigestInit_ex, EVP_DigestUpdate, EVP_DigestFinal_ex,
|
|
EVP_DigestInit, EVP_DigestFinal, 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_sha1,
|
|
EVP_sha224, EVP_sha256, EVP_sha384, EVP_sha512, EVP_mdc2,
|
|
EVP_ripemd160, EVP_blake2b_512, EVP_blake2s_256, EVP_get_digestbyname,
|
|
EVP_get_digestbynid, EVP_get_digestbyobj - EVP digest routines
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/evp.h>
|
|
|
|
EVP_MD_CTX *EVP_MD_CTX_new(void);
|
|
int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
|
|
void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
|
|
|
|
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_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);
|
|
|
|
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);
|
|
int EVP_MD_CTX_size(const EVP_MD *ctx);
|
|
int EVP_MD_CTX_block_size(const EVP_MD *ctx);
|
|
int EVP_MD_CTX_type(const EVP_MD *ctx);
|
|
|
|
const EVP_MD *EVP_md_null(void);
|
|
const EVP_MD *EVP_md2(void);
|
|
const EVP_MD *EVP_md5(void);
|
|
const EVP_MD *EVP_sha1(void);
|
|
const EVP_MD *EVP_mdc2(void);
|
|
const EVP_MD *EVP_ripemd160(void);
|
|
const EVP_MD *EVP_blake2b_512(void);
|
|
const EVP_MD *EVP_blake2s_256(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);
|
|
const EVP_MD *EVP_get_digestbynid(int type);
|
|
const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The EVP digest routines are a high level interface to message digests,
|
|
and should be used instead of the cipher-specific functions.
|
|
|
|
EVP_MD_CTX_new() allocates, initializes and returns a digest context.
|
|
|
|
EVP_MD_CTX_reset() resets the digest context B<ctx>. This can be used
|
|
to reuse an already existing context.
|
|
|
|
EVP_MD_CTX_free() cleans up digest context B<ctx> and frees up the
|
|
space allocated to it.
|
|
|
|
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 function such 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_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_sha1(), EVP_sha224(), EVP_sha256(),
|
|
EVP_sha384(), EVP_sha512(), EVP_mdc2(), EVP_ripemd160(), EVP_blake2b_512(), and
|
|
EVP_blake2s_256() return B<EVP_MD> structures for the MD2, MD5, SHA1, SHA224,
|
|
SHA256, SHA384, SHA512, MDC2, RIPEMD160, BLAKE2b-512, and BLAKE2s-256 digest
|
|
algorithms respectively.
|
|
|
|
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.
|
|
|
|
=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_sha1(),
|
|
EVP_mdc2(), EVP_ripemd160(), EVP_blake2b_512(), and EVP_blake2s_256() 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.
|
|
|
|
If digest contexts are not cleaned up after use
|
|
memory leaks will occur.
|
|
|
|
EVP_MD_CTX_size(), EVP_MD_CTX_block_size(), EVP_MD_CTX_type(),
|
|
EVP_get_digestbynid() and EVP_get_digestbyobj() are defined as
|
|
macros.
|
|
|
|
|
|
=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;
|
|
|
|
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_new();
|
|
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_free(mdctx);
|
|
|
|
printf("Digest is: ");
|
|
for (i = 0; i < md_len; i++)
|
|
printf("%02x", md_value[i]);
|
|
printf("\n");
|
|
|
|
exit(0);
|
|
}
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<dgst(1)>,
|
|
L<evp(7)>
|
|
|
|
=head1 HISTORY
|
|
|
|
B<EVP_MD_CTX> became opaque in OpenSSL 1.1. Consequently, stack
|
|
allocated B<EVP_MD_CTX>s are no longer supported.
|
|
|
|
EVP_MD_CTX_create() and EVP_MD_CTX_destroy() were renamed to
|
|
EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.
|
|
|
|
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. The legacy EVP_dss1()
|
|
was removed in OpenSSL 1.1.0
|
|
|
|
=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>.
|
|
|
|
=cut
|