| Current File : //usr/local/share/man/man3/EVP_MD_CTX_block_size.3 |
.\" Automatically generated by Pod::Man 2.27 (Pod::Simple 3.28)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings. \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote. \*(C+ will
.\" give a nicer C++. Capital omega is used to do unbreakable dashes and
.\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
. ds -- \(*W-
. ds PI pi
. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
. ds L" ""
. ds R" ""
. ds C` ""
. ds C' ""
'br\}
.el\{\
. ds -- \|\(em\|
. ds PI \(*p
. ds L" ``
. ds R" ''
. ds C`
. ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{
. if \nF \{
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. if !\nF==2 \{
. nr % 0
. nr F 2
. \}
. \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff
.if n \{\
. ds #H 0
. ds #V .8m
. ds #F .3m
. ds #[ \f1
. ds #] \fP
.\}
.if t \{\
. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
. ds #V .6m
. ds #F 0
. ds #[ \&
. ds #] \&
.\}
. \" simple accents for nroff and troff
.if n \{\
. ds ' \&
. ds ` \&
. ds ^ \&
. ds , \&
. ds ~ ~
. ds /
.\}
.if t \{\
. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
. \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
. \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
. \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
. ds : e
. ds 8 ss
. ds o a
. ds d- d\h'-1'\(ga
. ds D- D\h'-1'\(hy
. ds th \o'bp'
. ds Th \o'LP'
. ds ae ae
. ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "EVP_DIGESTINIT 3"
.TH EVP_DIGESTINIT 3 "2017-05-25" "1.1.0f" "OpenSSL"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "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_blake2b512, EVP_blake2s256, EVP_get_digestbyname,
EVP_get_digestbynid, EVP_get_digestbyobj \- EVP digest routines
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #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_blake2b512(void);
\& const EVP_MD *EVP_blake2s256(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);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \s-1EVP\s0 digest routines are a high level interface to message digests,
and should be used instead of the cipher-specific functions.
.PP
\&\fIEVP_MD_CTX_new()\fR allocates, initializes and returns a digest context.
.PP
\&\fIEVP_MD_CTX_reset()\fR resets the digest context \fBctx\fR. This can be used
to reuse an already existing context.
.PP
\&\fIEVP_MD_CTX_free()\fR cleans up digest context \fBctx\fR and frees up the
space allocated to it.
.PP
\&\fIEVP_DigestInit_ex()\fR sets up digest context \fBctx\fR to use a digest
\&\fBtype\fR from \s-1ENGINE \s0\fBimpl\fR. \fBctx\fR must be initialized before calling this
function. \fBtype\fR will typically be supplied by a function such as \fIEVP_sha1()\fR.
If \fBimpl\fR is \s-1NULL\s0 then the default implementation of digest \fBtype\fR is used.
.PP
\&\fIEVP_DigestUpdate()\fR hashes \fBcnt\fR bytes of data at \fBd\fR into the
digest context \fBctx\fR. This function can be called several times on the
same \fBctx\fR to hash additional data.
.PP
\&\fIEVP_DigestFinal_ex()\fR retrieves the digest value from \fBctx\fR and places
it in \fBmd\fR. If the \fBs\fR parameter is not \s-1NULL\s0 then the number of
bytes of data written (i.e. the length of the digest) will be written
to the integer at \fBs\fR, at most \fB\s-1EVP_MAX_MD_SIZE\s0\fR bytes will be written.
After calling \fIEVP_DigestFinal_ex()\fR no additional calls to \fIEVP_DigestUpdate()\fR
can be made, but \fIEVP_DigestInit_ex()\fR can be called to initialize a new
digest operation.
.PP
\&\fIEVP_MD_CTX_copy_ex()\fR can be used to copy the message digest state from
\&\fBin\fR to \fBout\fR. This is useful if large amounts of data are to be
hashed which only differ in the last few bytes. \fBout\fR must be initialized
before calling this function.
.PP
\&\fIEVP_DigestInit()\fR behaves in the same way as \fIEVP_DigestInit_ex()\fR except
the passed context \fBctx\fR does not have to be initialized, and it always
uses the default digest implementation.
.PP
\&\fIEVP_DigestFinal()\fR is similar to \fIEVP_DigestFinal_ex()\fR except the digest
context \fBctx\fR is automatically cleaned up.
.PP
\&\fIEVP_MD_CTX_copy()\fR is similar to \fIEVP_MD_CTX_copy_ex()\fR except the destination
\&\fBout\fR does not have to be initialized.
.PP
\&\fIEVP_MD_size()\fR and \fIEVP_MD_CTX_size()\fR return the size of the message digest
when passed an \fB\s-1EVP_MD\s0\fR or an \fB\s-1EVP_MD_CTX\s0\fR structure, i.e. the size of the
hash.
.PP
\&\fIEVP_MD_block_size()\fR and \fIEVP_MD_CTX_block_size()\fR return the block size of the
message digest when passed an \fB\s-1EVP_MD\s0\fR or an \fB\s-1EVP_MD_CTX\s0\fR structure.
.PP
\&\fIEVP_MD_type()\fR and \fIEVP_MD_CTX_type()\fR return the \s-1NID\s0 of the \s-1OBJECT IDENTIFIER\s0
representing the given message digest when passed an \fB\s-1EVP_MD\s0\fR structure.
For example EVP_MD_type(\fIEVP_sha1()\fR) returns \fBNID_sha1\fR. This function is
normally used when setting \s-1ASN1\s0 OIDs.
.PP
\&\fIEVP_MD_CTX_md()\fR returns the \fB\s-1EVP_MD\s0\fR structure corresponding to the passed
\&\fB\s-1EVP_MD_CTX\s0\fR.
.PP
\&\fIEVP_MD_pkey_type()\fR returns the \s-1NID\s0 of the public key signing algorithm associated
with this digest. For example \fIEVP_sha1()\fR is associated with \s-1RSA\s0 so this will
return \fBNID_sha1WithRSAEncryption\fR. Since digests and signature algorithms
are no longer linked this function is only retained for compatibility
reasons.
.PP
\&\fIEVP_md2()\fR, \fIEVP_md5()\fR, \fIEVP_sha1()\fR, \fIEVP_sha224()\fR, \fIEVP_sha256()\fR,
\&\fIEVP_sha384()\fR, \fIEVP_sha512()\fR, \fIEVP_mdc2()\fR, \fIEVP_ripemd160()\fR, \fIEVP_blake2b512()\fR, and
\&\fIEVP_blake2s256()\fR return \fB\s-1EVP_MD\s0\fR structures for the \s-1MD2, MD5, SHA1, SHA224,
SHA256, SHA384, SHA512, MDC2, RIPEMD160,\s0 BLAKE2b\-512, and BLAKE2s\-256 digest
algorithms respectively.
.PP
\&\fIEVP_md_null()\fR is a \*(L"null\*(R" message digest that does nothing: i.e. the hash it
returns is of zero length.
.PP
\&\fIEVP_get_digestbyname()\fR, \fIEVP_get_digestbynid()\fR and \fIEVP_get_digestbyobj()\fR
return an \fB\s-1EVP_MD\s0\fR structure when passed a digest name, a digest \s-1NID\s0 or
an \s-1ASN1_OBJECT\s0 structure respectively.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIEVP_DigestInit_ex()\fR, \fIEVP_DigestUpdate()\fR and \fIEVP_DigestFinal_ex()\fR return 1 for
success and 0 for failure.
.PP
\&\fIEVP_MD_CTX_copy_ex()\fR returns 1 if successful or 0 for failure.
.PP
\&\fIEVP_MD_type()\fR, \fIEVP_MD_pkey_type()\fR and \fIEVP_MD_type()\fR return the \s-1NID\s0 of the
corresponding \s-1OBJECT IDENTIFIER\s0 or NID_undef if none exists.
.PP
\&\fIEVP_MD_size()\fR, \fIEVP_MD_block_size()\fR, \fIEVP_MD_CTX_size()\fR and
\&\fIEVP_MD_CTX_block_size()\fR return the digest or block size in bytes.
.PP
\&\fIEVP_md_null()\fR, \fIEVP_md2()\fR, \fIEVP_md5()\fR, \fIEVP_sha1()\fR,
\&\fIEVP_mdc2()\fR, \fIEVP_ripemd160()\fR, \fIEVP_blake2b512()\fR, and \fIEVP_blake2s256()\fR return
pointers to the corresponding \s-1EVP_MD\s0 structures.
.PP
\&\fIEVP_get_digestbyname()\fR, \fIEVP_get_digestbynid()\fR and \fIEVP_get_digestbyobj()\fR
return either an \fB\s-1EVP_MD\s0\fR structure or \s-1NULL\s0 if an error occurs.
.SH "NOTES"
.IX Header "NOTES"
The \fB\s-1EVP\s0\fR 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.
.PP
New applications should use the \s-1SHA2\s0 digest algorithms such as \s-1SHA256.\s0
The other digest algorithms are still in common use.
.PP
For most applications the \fBimpl\fR parameter to \fIEVP_DigestInit_ex()\fR will be
set to \s-1NULL\s0 to use the default digest implementation.
.PP
The functions \fIEVP_DigestInit()\fR, \fIEVP_DigestFinal()\fR and \fIEVP_MD_CTX_copy()\fR are
obsolete but are retained to maintain compatibility with existing code. New
applications should use \fIEVP_DigestInit_ex()\fR, \fIEVP_DigestFinal_ex()\fR and
\&\fIEVP_MD_CTX_copy_ex()\fR 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.
.PP
If digest contexts are not cleaned up after use
memory leaks will occur.
.PP
\&\fIEVP_MD_CTX_size()\fR, \fIEVP_MD_CTX_block_size()\fR, \fIEVP_MD_CTX_type()\fR,
\&\fIEVP_get_digestbynid()\fR and \fIEVP_get_digestbyobj()\fR are defined as
macros.
.SH "EXAMPLE"
.IX Header "EXAMPLE"
This example digests the data \*(L"Test Message\en\*(R" and \*(L"Hello World\en\*(R", using the
digest name passed on the command line.
.PP
.Vb 2
\& #include <stdio.h>
\& #include <openssl/evp.h>
\&
\& main(int argc, char *argv[])
\& {
\& EVP_MD_CTX *mdctx;
\& const EVP_MD *md;
\& char mess1[] = "Test Message\en";
\& char mess2[] = "Hello World\en";
\& unsigned char md_value[EVP_MAX_MD_SIZE];
\& int md_len, i;
\&
\& if(!argv[1]) {
\& printf("Usage: mdtest digestname\en");
\& exit(1);
\& }
\&
\& md = EVP_get_digestbyname(argv[1]);
\&
\& if(!md) {
\& printf("Unknown message digest %s\en", 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("\en");
\&
\& exit(0);
\& }
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIdgst\fR\|(1),
\&\fIevp\fR\|(7)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fB\s-1EVP_MD_CTX\s0\fR became opaque in OpenSSL 1.1. Consequently, stack
allocated \fB\s-1EVP_MD_CTX\s0\fRs are no longer supported.
.PP
\&\fIEVP_MD_CTX_create()\fR and \fIEVP_MD_CTX_destroy()\fR were renamed to
\&\fIEVP_MD_CTX_new()\fR and \fIEVP_MD_CTX_free()\fR in OpenSSL 1.1.
.PP
The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
later, so now \fIEVP_sha1()\fR can be used with \s-1RSA\s0 and \s-1DSA.\s0 The legacy \fIEVP_dss1()\fR
was removed in OpenSSL 1.1.0
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2000\-2016 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.