Mon Jan 13 19:28:08 2003
Standard preamble:
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\\$1
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.... 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. | will give a
real vertical bar. \*(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-|\(bv\*(Tr . 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\} . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' 'br\}
If the F register is turned on, we'll generate index entries on stderr
for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and
index entries marked with X<> in POD. Of course, you'll have to process
the output yourself in some meaningful fashion.
. de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . nr % 0 . rr F .\}
For nroff, turn off justification. Always turn off hyphenation; it
makes way too many mistakes in technical documents.
Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
Fear. Run. Save yourself. No user-serviceable parts.
.bd B 3 . \" fudge factors for nroff and troff . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] .\} . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} . 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 . \" corrections for vroff . \" for low resolution devices (crt and lpr) \{\ . 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 .\} ======================================================================
Title "EVP_SealInit 3"
\fIEVP_SealInit() initializes a cipher context ctx for encryption with cipher type using a random secret key and \s-1IV\s0 supplied in the iv parameter. type is normally supplied by a function such as EVP_des_cbc(). The secret key is encrypted using one or more public keys, this allows the same encrypted data to be decrypted using any of the corresponding private keys. ek is an array of buffers where the public key encrypted secret key will be written, each buffer must contain enough room for the corresponding encrypted key: that is \fBek[i] must have room for EVP_PKEY_size(pubk[i]) bytes. The actual size of each encrypted secret key is written to the array ekl. pubk is an array of npubk public keys.
\fIEVP_SealUpdate() and EVP_SealFinal() have exactly the same properties as the EVP_EncryptUpdate() and EVP_EncryptFinal() routines, as documented on the EVP_EncryptInit(3) manual page.
\fIEVP_SealUpdate() and EVP_SealFinal() return 1 for success and 0 for failure.
The public key must be \s-1RSA\s0 because it is the only OpenSSL public key algorithm that supports key transport.
Envelope encryption is the usual method of using public key encryption on large amounts of data, this is because public key encryption is slow but symmetric encryption is fast. So symmetric encryption is used for bulk encryption and the small random symmetric key used is transferred using public key encryption.
It is possible to call EVP_SealInit() twice in the same way as \fIEVP_EncryptInit(). The first call should have npubk set to 0 and (after setting any cipher parameters) it should be called again with type set to \s-1NULL\s0.