| blob | ffc500b3a8112b65bb2f7b3b0ed8526842992b7c |
1 .\" Automatically generated by Pod::Man 2.12 (Pod::Simple 3.05)
2 .\"
3 .\" Standard preamble:
4 .\" ========================================================================
5 .de Sh \" Subsection heading
6 .br
7 .if t .Sp
8 .ne 5
9 .PP
10 \fB\\$1\fR
11 .PP
12 ..
13 .de Sp \" Vertical space (when we can't use .PP)
14 .if t .sp .5v
15 .if n .sp
16 ..
17 .de Vb \" Begin verbatim text
18 .ft CW
19 .nf
20 .ne \\$1
21 ..
22 .de Ve \" End verbatim text
23 .ft R
24 .fi
25 ..
26 .\" Set up some character translations and predefined strings. \*(-- will
27 .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
28 .\" double quote, and \*(R" will give a right double quote. \*(C+ will
29 .\" give a nicer C++. Capital omega is used to do unbreakable dashes and
30 .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
31 .\" nothing in troff, for use with C<>.
32 .tr \(*W-
33 .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
34 .ie n \{\
35 . ds -- \(*W-
36 . ds PI pi
37 . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
38 . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
39 . ds L" ""
40 . ds R" ""
41 . ds C` ""
42 . ds C' ""
43 'br\}
44 .el\{\
45 . ds -- \|\(em\|
46 . ds PI \(*p
47 . ds L" ``
48 . ds R" ''
49 'br\}
50 .\"
51 .\" If the F register is turned on, we'll generate index entries on stderr for
52 .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
53 .\" entries marked with X<> in POD. Of course, you'll have to process the
54 .\" output yourself in some meaningful fashion.
55 .if \nF \{\
56 . de IX
57 . tm Index:\\$1\t\\n%\t"\\$2"
58 ..
59 . nr % 0
60 . rr F
61 .\}
62 .\"
63 .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
64 .\" Fear. Run. Save yourself. No user-serviceable parts.
65 . \" fudge factors for nroff and troff
66 .if n \{\
67 . ds #H 0
68 . ds #V .8m
69 . ds #F .3m
70 . ds #[ \f1
71 . ds #] \fP
72 .\}
73 .if t \{\
74 . ds #H ((1u-(\\\\n(.fu%2u))*.13m)
75 . ds #V .6m
76 . ds #F 0
77 . ds #[ \&
78 . ds #] \&
79 .\}
80 . \" simple accents for nroff and troff
81 .if n \{\
82 . ds ' \&
83 . ds ` \&
84 . ds ^ \&
85 . ds , \&
86 . ds ~ ~
87 . ds /
88 .\}
89 .if t \{\
90 . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
91 . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
92 . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
93 . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
94 . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
95 . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
96 .\}
97 . \" troff and (daisy-wheel) nroff accents
98 .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
99 .ds 8 \h'\*(#H'\(*b\h'-\*(#H'
100 .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
101 .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
102 .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
103 .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
104 .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
105 .ds ae a\h'-(\w'a'u*4/10)'e
106 .ds Ae A\h'-(\w'A'u*4/10)'E
107 . \" corrections for vroff
108 .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
109 .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
110 . \" for low resolution devices (crt and lpr)
111 .if \n(.H>23 .if \n(.V>19 \
112 \{\
113 . ds : e
114 . ds 8 ss
115 . ds o a
116 . ds d- d\h'-1'\(ga
117 . ds D- D\h'-1'\(hy
118 . ds th \o'bp'
119 . ds Th \o'LP'
120 . ds ae ae
121 . ds Ae AE
122 .\}
123 .rm #[ #] #H #V #F C
124 .\" ========================================================================
125 .\"
126 .IX Title "EVP_SignInit 3"
127 .TH EVP_SignInit 3 "2007-10-24" "0.9.8g" "OpenSSL"
128 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
129 .\" way too many mistakes in technical documents.
130 .if n .ad l
131 .nh
132 .SH "NAME"
133 EVP_SignInit, EVP_SignUpdate, EVP_SignFinal \- EVP signing functions
134 .SH "SYNOPSIS"
135 .IX Header "SYNOPSIS"
136 .Vb 1
137 \& #include <openssl/evp.h>
138 \&
139 \& int EVP_SignInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
140 \& int EVP_SignUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
141 \& int EVP_SignFinal(EVP_MD_CTX *ctx,unsigned char *sig,unsigned int *s, EVP_PKEY *pkey);
142 \&
143 \& void EVP_SignInit(EVP_MD_CTX *ctx, const EVP_MD *type);
144 \&
145 \& int EVP_PKEY_size(EVP_PKEY *pkey);
146 .Ve
147 .SH "DESCRIPTION"
148 .IX Header "DESCRIPTION"
149 The \s-1EVP\s0 signature routines are a high level interface to digital
150 signatures.
151 .PP
152 \&\fIEVP_SignInit_ex()\fR sets up signing context \fBctx\fR to use digest
153 \&\fBtype\fR from \s-1ENGINE\s0 \fBimpl\fR. \fBctx\fR must be initialized with
154 \&\fIEVP_MD_CTX_init()\fR before calling this function.
155 .PP
156 \&\fIEVP_SignUpdate()\fR hashes \fBcnt\fR bytes of data at \fBd\fR into the
157 signature context \fBctx\fR. This function can be called several times on the
158 same \fBctx\fR to include additional data.
159 .PP
160 \&\fIEVP_SignFinal()\fR signs the data in \fBctx\fR using the private key \fBpkey\fR and
161 places the signature in \fBsig\fR. The number of bytes of data written (i.e. the
162 length of the signature) will be written to the integer at \fBs\fR, at most
163 EVP_PKEY_size(pkey) bytes will be written.
164 .PP
165 \&\fIEVP_SignInit()\fR initializes a signing context \fBctx\fR to use the default
166 implementation of digest \fBtype\fR.
167 .PP
168 \&\fIEVP_PKEY_size()\fR returns the maximum size of a signature in bytes. The actual
169 signature returned by \fIEVP_SignFinal()\fR may be smaller.
170 .SH "RETURN VALUES"
171 .IX Header "RETURN VALUES"
172 \&\fIEVP_SignInit_ex()\fR, \fIEVP_SignUpdate()\fR and \fIEVP_SignFinal()\fR return 1
173 for success and 0 for failure.
174 .PP
175 \&\fIEVP_PKEY_size()\fR returns the maximum size of a signature in bytes.
176 .PP
177 The error codes can be obtained by \fIERR_get_error\fR\|(3).
178 .SH "NOTES"
179 .IX Header "NOTES"
180 The \fB\s-1EVP\s0\fR interface to digital signatures should almost always be used in
181 preference to the low level interfaces. This is because the code then becomes
182 transparent to the algorithm used and much more flexible.
183 .PP
184 Due to the link between message digests and public key algorithms the correct
185 digest algorithm must be used with the correct public key type. A list of
186 algorithms and associated public key algorithms appears in
187 \&\fIEVP_DigestInit\fR\|(3).
188 .PP
189 When signing with \s-1DSA\s0 private keys the random number generator must be seeded
190 or the operation will fail. The random number generator does not need to be
191 seeded for \s-1RSA\s0 signatures.
192 .PP
193 The call to \fIEVP_SignFinal()\fR internally finalizes a copy of the digest context.
194 This means that calls to \fIEVP_SignUpdate()\fR and \fIEVP_SignFinal()\fR can be called
195 later to digest and sign additional data.
196 .PP
197 Since only a copy of the digest context is ever finalized the context must
198 be cleaned up after use by calling \fIEVP_MD_CTX_cleanup()\fR or a memory leak
199 will occur.
200 .SH "BUGS"
201 .IX Header "BUGS"
202 Older versions of this documentation wrongly stated that calls to
203 \&\fIEVP_SignUpdate()\fR could not be made after calling \fIEVP_SignFinal()\fR.
204 .SH "SEE ALSO"
205 .IX Header "SEE ALSO"
206 \&\fIEVP_VerifyInit\fR\|(3),
207 \&\fIEVP_DigestInit\fR\|(3), \fIerr\fR\|(3),
208 \&\fIevp\fR\|(3), \fIhmac\fR\|(3), \fImd2\fR\|(3),
209 \&\fImd5\fR\|(3), \fImdc2\fR\|(3), \fIripemd\fR\|(3),
210 \&\fIsha\fR\|(3), \fIdgst\fR\|(1)
211 .SH "HISTORY"
212 .IX Header "HISTORY"
213 \&\fIEVP_SignInit()\fR, \fIEVP_SignUpdate()\fR and \fIEVP_SignFinal()\fR are
214 available in all versions of SSLeay and OpenSSL.
215 .PP
216 \&\fIEVP_SignInit_ex()\fR was added in OpenSSL 0.9.7.