1 .\" Automatically generated by Pod::Man 2.23 (Pod::Simple 3.22)
4 .\" ========================================================================
5 .de Sp \" Vertical space (when we can't use .PP)
9 .de Vb \" Begin verbatim text
14 .de Ve \" End verbatim text
18 .\" Set up some character translations and predefined strings. \*(-- will
19 .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
20 .\" double quote, and \*(R" will give a right double quote. \*(C+ will
21 .\" give a nicer C++. Capital omega is used to do unbreakable dashes and
22 .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
23 .\" nothing in troff, for use with C<>.
25 .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
29 . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
30 . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
43 .\" Escape single quotes in literal strings from groff's Unicode transform.
47 .\" If the F register is turned on, we'll generate index entries on stderr for
48 .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
49 .\" entries marked with X<> in POD. Of course, you'll have to process the
50 .\" output yourself in some meaningful fashion.
53 . tm Index:\\$1\t\\n%\t"\\$2"
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
74 . ds #H ((1u-(\\\\n(.fu%2u))*.13m)
80 . \" simple accents for nroff and troff
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'
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 \
124 .\" ========================================================================
126 .IX Title "EVP_SealInit 3"
127 .TH EVP_SealInit 3 "2012-05-10" "1.0.1c" "OpenSSL"
128 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
129 .\" way too many mistakes in technical documents.
133 EVP_SealInit, EVP_SealUpdate, EVP_SealFinal \- EVP envelope encryption
135 .IX Header "SYNOPSIS"
137 \& #include <openssl/evp.h>
139 \& int EVP_SealInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
140 \& unsigned char **ek, int *ekl, unsigned char *iv,
141 \& EVP_PKEY **pubk, int npubk);
142 \& int EVP_SealUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
143 \& int *outl, unsigned char *in, int inl);
144 \& int EVP_SealFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
148 .IX Header "DESCRIPTION"
149 The \s-1EVP\s0 envelope routines are a high level interface to envelope
150 encryption. They generate a random key and \s-1IV\s0 (if required) then
151 \&\*(L"envelope\*(R" it by using public key encryption. Data can then be
152 encrypted using this key.
154 \&\fIEVP_SealInit()\fR initializes a cipher context \fBctx\fR for encryption
155 with cipher \fBtype\fR using a random secret key and \s-1IV\s0. \fBtype\fR is normally
156 supplied by a function such as \fIEVP_des_cbc()\fR. The secret key is encrypted
157 using one or more public keys, this allows the same encrypted data to be
158 decrypted using any of the corresponding private keys. \fBek\fR is an array of
159 buffers where the public key encrypted secret key will be written, each buffer
160 must contain enough room for the corresponding encrypted key: that is
161 \&\fBek[i]\fR must have room for \fBEVP_PKEY_size(pubk[i])\fR bytes. The actual
162 size of each encrypted secret key is written to the array \fBekl\fR. \fBpubk\fR is
163 an array of \fBnpubk\fR public keys.
165 The \fBiv\fR parameter is a buffer where the generated \s-1IV\s0 is written to. It must
166 contain enough room for the corresponding cipher's \s-1IV\s0, as determined by (for
167 example) EVP_CIPHER_iv_length(type).
169 If the cipher does not require an \s-1IV\s0 then the \fBiv\fR parameter is ignored
170 and can be \fB\s-1NULL\s0\fR.
172 \&\fIEVP_SealUpdate()\fR and \fIEVP_SealFinal()\fR have exactly the same properties
173 as the \fIEVP_EncryptUpdate()\fR and \fIEVP_EncryptFinal()\fR routines, as
174 documented on the \fIEVP_EncryptInit\fR\|(3) manual
177 .IX Header "RETURN VALUES"
178 \&\fIEVP_SealInit()\fR returns 0 on error or \fBnpubk\fR if successful.
180 \&\fIEVP_SealUpdate()\fR and \fIEVP_SealFinal()\fR return 1 for success and 0 for
184 Because a random secret key is generated the random number generator
185 must be seeded before calling \fIEVP_SealInit()\fR.
187 The public key must be \s-1RSA\s0 because it is the only OpenSSL public key
188 algorithm that supports key transport.
190 Envelope encryption is the usual method of using public key encryption
191 on large amounts of data, this is because public key encryption is slow
192 but symmetric encryption is fast. So symmetric encryption is used for
193 bulk encryption and the small random symmetric key used is transferred
194 using public key encryption.
196 It is possible to call \fIEVP_SealInit()\fR twice in the same way as
197 \&\fIEVP_EncryptInit()\fR. The first call should have \fBnpubk\fR set to 0
198 and (after setting any cipher parameters) it should be called again
199 with \fBtype\fR set to \s-1NULL\s0.
201 .IX Header "SEE ALSO"
202 \&\fIevp\fR\|(3), \fIrand\fR\|(3),
203 \&\fIEVP_EncryptInit\fR\|(3),
204 \&\fIEVP_OpenInit\fR\|(3)
207 \&\fIEVP_SealFinal()\fR did not return a value before OpenSSL 0.9.7.