openssl-prebuild/linux_amd64/ssl/share/man/man7/EVP_KDF-PBKDF2.7

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.\" ========================================================================
.\"
.IX Title "EVP_KDF-PBKDF2 7"
.TH EVP_KDF-PBKDF2 7 "2020-03-02" "3.0.0-dev" "OpenSSL"
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.nh
.SH "NAME"
EVP_KDF\-PBKDF2 \- The PBKDF2 EVP_KDF implementation
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Support for computing the \fB\s-1PBKDF2\s0\fR password-based \s-1KDF\s0 through the \fB\s-1EVP_KDF\s0\fR
\&\s-1API\s0.
.PP
The \s-1EVP_KDF\-PBKDF2\s0 algorithm implements the \s-1PBKDF2\s0 password-based key
derivation function, as described in \s-1SP800\-132\s0; it derives a key from a password
using a salt and iteration count.
.SS "Identity"
.IX Subsection "Identity"
\&\*(L"\s-1PBKDF2\s0\*(R" is the name for this implementation; it
can be used with the \fIEVP_KDF_fetch()\fR function.
.SS "Supported parameters"
.IX Subsection "Supported parameters"
The supported parameters are:
.ie n .IP """pass"" (\fB\s-1OSSL_KDF_PARAM_PASSWORD\s0\fR) <octet string>" 4
.el .IP "``pass'' (\fB\s-1OSSL_KDF_PARAM_PASSWORD\s0\fR) <octet string>" 4
.IX Item "pass (OSSL_KDF_PARAM_PASSWORD) <octet string>"
.PD 0
.ie n .IP """salt"" (\fB\s-1OSSL_KDF_PARAM_SALT\s0\fR) <octet string>" 4
.el .IP "``salt'' (\fB\s-1OSSL_KDF_PARAM_SALT\s0\fR) <octet string>" 4
.IX Item "salt (OSSL_KDF_PARAM_SALT) <octet string>"
.ie n .IP """iter"" (\fB\s-1OSSL_KDF_PARAM_ITER\s0\fR) <unsigned integer>" 4
.el .IP "``iter'' (\fB\s-1OSSL_KDF_PARAM_ITER\s0\fR) <unsigned integer>" 4
.IX Item "iter (OSSL_KDF_PARAM_ITER) <unsigned integer>"
.PD
This parameter has a default value of 2048.
.ie n .IP """properties"" (\fB\s-1OSSL_KDF_PARAM_PROPERTIES\s0\fR) <\s-1UTF8\s0 string>" 4
.el .IP "``properties'' (\fB\s-1OSSL_KDF_PARAM_PROPERTIES\s0\fR) <\s-1UTF8\s0 string>" 4
.IX Item "properties (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string>"
.PD 0
.ie n .IP """digest"" (\fB\s-1OSSL_KDF_PARAM_DIGEST\s0\fR) <\s-1UTF8\s0 string>" 4
.el .IP "``digest'' (\fB\s-1OSSL_KDF_PARAM_DIGEST\s0\fR) <\s-1UTF8\s0 string>" 4
.IX Item "digest (OSSL_KDF_PARAM_DIGEST) <UTF8 string>"
.PD
These parameters work as described in \*(L"\s-1PARAMETERS\s0\*(R" in \s-1\fIEVP_KDF\s0\fR\|(3).
.ie n .IP """pkcs5"" (\fB\s-1OSSL_KDF_PARAM_PKCS5\s0\fR) <integer>" 4
.el .IP "``pkcs5'' (\fB\s-1OSSL_KDF_PARAM_PKCS5\s0\fR) <integer>" 4
.IX Item "pkcs5 (OSSL_KDF_PARAM_PKCS5) <integer>"
This parameter can be used to enable or disable \s-1SP800\-132\s0 compliance checks.
Setting the mode to 0 enables the compliance checks.
.Sp
The checks performed are:
.RS 4
.IP "\- the iteration count is at least 1000." 4
.IX Item "- the iteration count is at least 1000."
.PD 0
.IP "\- the salt length is at least 128 bits." 4
.IX Item "- the salt length is at least 128 bits."
.IP "\- the derived key length is at least 112 bits." 4
.IX Item "- the derived key length is at least 112 bits."
.RE
.RS 4
.PD
.Sp
The default provider uses a default mode of 1 for backwards compatibility,
and the fips provider uses a default mode of 0.
.Sp
The value string is expected to be a decimal number 0 or 1.
.RE
.SH "NOTES"
.IX Header "NOTES"
A typical application of this algorithm is to derive keying material for an
encryption algorithm from a password in the \*(L"pass\*(R", a salt in \*(L"salt\*(R",
and an iteration count.
.PP
Increasing the \*(L"iter\*(R" 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
No assumption is made regarding the given password; it is simply treated as a
byte sequence.
.SH "CONFORMING TO"
.IX Header "CONFORMING TO"
\&\s-1SP800\-132\s0
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1\fIEVP_KDF\s0\fR\|(3),
\&\fIEVP_KDF_CTX_new\fR\|(3),
\&\fIEVP_KDF_CTX_free\fR\|(3),
\&\fIEVP_KDF_CTX_set_params\fR\|(3),
\&\fIEVP_KDF_derive\fR\|(3),
\&\*(L"\s-1PARAMETERS\s0\*(R" in \s-1\fIEVP_KDF\s0\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
This functionality was added to OpenSSL 3.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2018\-2019 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (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>.