- NAME
- SYNOPSIS
- DESCRIPTION
- STRING CTRLS
- NOTES
- RETURN VALUES
- SEE ALSO
- COPYRIGHT

# 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

# SYNOPSIS

    #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);

# DESCRIPTION

These functions are used to set up the necessary data to use the scrypt KDF. For more information on scrypt, see scrypt(7).

EVP_PKEY_CTX_set1_scrypt_salt() sets the saltlen bytes long salt value.

EVP_PKEY_CTX_set_scrypt_N(), EVP_PKEY_CTX_set_scrypt_r() and EVP_PKEY_CTX_set_scrypt_p() configure the work factors N, r and p.

EVP_PKEY_CTX_set_scrypt_maxmem_bytes() sets how much RAM key derivation may maximally use, given in bytes. If RAM is exceeded because the load factors are chosen too high, the key derivation will fail.

# STRING CTRLS

scrypt also supports string based control operations via EVP_PKEY_CTX_ctrl_str(3). Similarly, the salt can either be specified using the type parameter "salt" or in hex encoding by using the "hexsalt" parameter. The work factors N, r and p as well as maxmem_bytes can be set by using the parameters "N", "r", "p" and "maxmem_bytes", respectively.

# NOTES

The scrypt KDF also uses EVP_PKEY_CTX_set1_pbe_pass() as well as the value from the string controls "pass" and "hexpass". See EVP_PKEY_CTX_set1_pbe_pass(3).

All the functions described here are implemented as macros.

# 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.

# SEE ALSO

scrypt(7), EVP_PKEY_CTX_new(3), EVP_PKEY_CTX_ctrl_str(3), EVP_PKEY_derive(3)

# COPYRIGHT

Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.