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.\"
.IX Title "EVP_PKEY_CTX_SET_SCRYPT_N 3"
.TH EVP_PKEY_CTX_SET_SCRYPT_N 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
EVP_PKEY_CTX_set1_scrypt_salt, EVP_PKEY_CTX_set_scrypt_N, EVP_PKEY_CTX_set_scrypt_r, EVP_PKEY_CTX_set_scrypt_p, EVP_PKEY_CTX_set_scrypt_maxmem_bytes \&\- EVP_PKEY scrypt KDF support functions
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/kdf.h>
\&
\& int EVP_PKEY_CTX_set1_scrypt_salt(EVP_PKEY_CTX *pctx, unsigned char *salt,
\&                                   int saltlen);
\&
\& int EVP_PKEY_CTX_set_scrypt_N(EVP_PKEY_CTX *pctx, uint64_t N);
\&
\& int EVP_PKEY_CTX_set_scrypt_r(EVP_PKEY_CTX *pctx, uint64_t r);
\&
\& int EVP_PKEY_CTX_set_scrypt_p(EVP_PKEY_CTX *pctx, uint64_t p);
\&
\& int EVP_PKEY_CTX_set_scrypt_maxmem_bytes(EVP_PKEY_CTX *pctx,
\&                                          uint64_t maxmem);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
These functions are used to set up the necessary data to use the
scrypt \s-1KDF.\s0
For more information on scrypt, see \fBscrypt\fR\|(7).
.PP
\&\fBEVP_PKEY_CTX_set1_scrypt_salt()\fR sets the \fBsaltlen\fR bytes long salt
value.
.PP
\&\fBEVP_PKEY_CTX_set_scrypt_N()\fR, \fBEVP_PKEY_CTX_set_scrypt_r()\fR and
\&\fBEVP_PKEY_CTX_set_scrypt_p()\fR configure the work factors N, r and p.
.PP
\&\fBEVP_PKEY_CTX_set_scrypt_maxmem_bytes()\fR sets how much \s-1RAM\s0 key
derivation may maximally use, given in bytes.
If \s-1RAM\s0 is exceeded because the load factors are chosen too high, the
key derivation will fail.
.SH "STRING CTRLS"
.IX Header "STRING CTRLS"
scrypt also supports string based control operations via
\&\fBEVP_PKEY_CTX_ctrl_str\fR\|(3).
Similarly, the \fBsalt\fR can either be specified using the \fBtype\fR
parameter \*(L"salt\*(R" or in hex encoding by using the \*(L"hexsalt\*(R" parameter.
The work factors \fBN\fR, \fBr\fR and \fBp\fR as well as \fBmaxmem_bytes\fR can be
set by using the parameters \*(L"N\*(R", \*(L"r\*(R", \*(L"p\*(R" and \*(L"maxmem_bytes\*(R",
respectively.
.SH "NOTES"
.IX Header "NOTES"
The scrypt \s-1KDF\s0 also uses \fBEVP_PKEY_CTX_set1_pbe_pass()\fR as well as
the value from the string controls \*(L"pass\*(R" and \*(L"hexpass\*(R".
See \fBEVP_PKEY_CTX_set1_pbe_pass\fR\|(3).
.PP
All the functions described here are implemented as macros.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
All these functions return 1 for success and 0 or a negative value for
failure.
In particular a return value of \-2 indicates the operation is not
supported by the public key algorithm.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBscrypt\fR\|(7),
\&\fBEVP_PKEY_CTX_new\fR\|(3),
\&\fBEVP_PKEY_CTX_ctrl_str\fR\|(3),
\&\fBEVP_PKEY_derive\fR\|(3)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2017\-2018 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>.