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Diffstat (limited to 'secure/lib/libcrypto/man/EVP_BytesToKey.3')
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diff --git a/secure/lib/libcrypto/man/EVP_BytesToKey.3 b/secure/lib/libcrypto/man/EVP_BytesToKey.3 new file mode 100644 index 000000000000..8fd3b341dc9d --- /dev/null +++ b/secure/lib/libcrypto/man/EVP_BytesToKey.3 @@ -0,0 +1,206 @@ +.\" Automatically generated by Pod::Man 4.09 (Pod::Simple 3.35) +.\" +.\" 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++. 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Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.if n .ad l +.nh +.SH "NAME" +EVP_BytesToKey \- password based encryption routine +.SH "SYNOPSIS" +.IX 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 +.SH "DESCRIPTION" +.IX Header "DESCRIPTION" +\&\fIEVP_BytesToKey()\fR derives a key and \s-1IV\s0 from various parameters. \fBtype\fR is +the cipher to derive the key and \s-1IV\s0 for. \fBmd\fR is the message digest to use. +The \fBsalt\fR parameter 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. \fBdata\fR is a buffer containing +\&\fBdatal\fR bytes which is used to derive the keying data. \fBcount\fR is the +iteration count to use. The derived key and \s-1IV\s0 will be written to \fBkey\fR +and \fBiv\fR respectively. +.SH "NOTES" +.IX Header "NOTES" +A typical application of this function is to derive keying material for an +encryption algorithm from a password in the \fBdata\fR parameter. +.PP +Increasing the \fBcount\fR parameter slows down the algorithm which makes it +harder for an attacker to perform a brute force attack using a large number +of candidate passwords. +.PP +If the total key and \s-1IV\s0 length is less than the digest length and +\&\fB\s-1MD5\s0\fR 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. +.PP +Newer applications should use a more modern algorithm such as \s-1PBKDF2\s0 as +defined in PKCS#5v2.1 and provided by \s-1PKCS5_PBKDF2_HMAC.\s0 +.SH "KEY DERIVATION ALGORITHM" +.IX 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: +.PP +.Vb 1 +\& D_i = HASH^count(D_(i\-1) || data || salt) +.Ve +.PP +where || denotes concatenation, 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. +.PP +The initial bytes are used for the key and the subsequent bytes for +the \s-1IV.\s0 +.SH "RETURN VALUES" +.IX Header "RETURN VALUES" +If \fBdata\fR is \s-1NULL,\s0 then \fIEVP_BytesToKey()\fR returns the number of bytes +needed to store the derived key. +Otherwise, \fIEVP_BytesToKey()\fR returns the size of the derived key in bytes, +or 0 on error. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +\&\fIevp\fR\|(7), \fIRAND_bytes\fR\|(3), +\&\s-1\fIPKCS5_PBKDF2_HMAC\s0\fR\|(3), +\&\fIEVP_EncryptInit\fR\|(3) +.SH "COPYRIGHT" +.IX Header "COPYRIGHT" +Copyright 2001\-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>. |