Automatically generated by Pod::Man 2.27 (Pod::Simple 3.28)

Standard preamble:
========================================================================
..

..

.. 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 -- \(*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" '' . ds C` . ds C' 'br\}
Escape single quotes in literal strings from groff's Unicode transform.

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'.
.. .nr rF 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 . 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_BytesToKey 3" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
EVP_BytesToKey - password based encryption routine Header "SYNOPSIS" .Vb 1 #include <openssl/evp.h> \& int EVP_BytesToKey(const EVP_CIPHER *type,const EVP_MD *md, const unsigned char *salt, const unsigned char *data, int datal, int count, unsigned char *key,unsigned char *iv); .Ve Header "DESCRIPTION" \fIEVP_BytesToKey() derives a key and \s-1IV\s0 from various parameters. type is the cipher to derive the key and \s-1IV\s0 for. md is the message digest to use. The salt paramter is used as a salt in the derivation: it should point to an 8 byte buffer or \s-1NULL\s0 if no salt is used. data is a buffer containing \fBdatal bytes which is used to derive the keying data. count is the iteration count to use. The derived key and \s-1IV\s0 will be written to key and iv respectively. Header "NOTES" A typical application of this function is to derive keying material for an encryption algorithm from a password in the data parameter.

Increasing the count parameter slows down the algorithm which makes it harder for an attacker to peform a brute force attack using a large number of candidate passwords.

If the total key and \s-1IV\s0 length is less than the digest length and \fB\s-1MD5\s0 is used then the derivation algorithm is compatible with PKCS#5 v1.5 otherwise a non standard extension is used to derive the extra data.

Newer applications should use more standard algorithms such as PKCS#5 v2.0 for key derivation.

Header "KEY DERIVATION ALGORITHM" The key and \s-1IV\s0 is derived by concatenating D_1, D_2, etc until enough data is available for the key and \s-1IV.\s0 D_i is defined as:

.Vb 1 D_i = HASH^count(D_(i-1) || data || salt) .Ve

where || denotes concatentaion, D_0 is empty, \s-1HASH\s0 is the digest algorithm in use, HASH^1(data) is simply \s-1HASH\s0(data), HASH^2(data) is \s-1HASH\s0(\s-1HASH\s0(data)) and so on.

The initial bytes are used for the key and the subsequent bytes for the \s-1IV.\s0

Header "RETURN VALUES" \fIEVP_BytesToKey() returns the size of the derived key in bytes. Header "SEE ALSO" \fIevp\|(3), rand\|(3), \fIEVP_EncryptInit\|(3) Header "HISTORY"