SRP_VBASE_NEW(3)

NAME
SRP_VBASE_new, SRP_VBASE_free, SRP_VBASE_init, SRP_VBASE_add0_user, SRP_VBASE_get1_by_user, SRP_VBASE_get_by_user - Functions to create and manage a stack of SRP user verifier information

SYNOPSIS
 #include <openssl/srp.h>

 SRP_VBASE *SRP_VBASE_new(char *seed_key);
 void SRP_VBASE_free(SRP_VBASE *vb);

 int SRP_VBASE_init(SRP_VBASE *vb, char *verifier_file);

 int SRP_VBASE_add0_user(SRP_VBASE *vb, SRP_user_pwd *user_pwd);
 SRP_user_pwd *SRP_VBASE_get1_by_user(SRP_VBASE *vb, char *username);
 SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username);

DESCRIPTION
The SRP_VBASE_new() function allocates a structure to store server side SRP verifier information. If seed_key is not NULL a copy is stored and used to generate dummy parameters for users that are not found by SRP_VBASE_get1_by_user(). This allows the server to hide the fact that it doesn't have a verifier for a particular username, as described in section 2.5.1.3 'Unknown SRP' of RFC 5054. The seed string should contain random NUL terminated binary data (therefore the random data should not contain NUL bytes!).

The SRP_VBASE_free() function frees up the vb structure. If vb is NULL, nothing is done.

The SRP_VBASE_init() function parses the information in a verifier file and populates the vb structure. The verifier file is a text file containing multiple entries, whose format is: flag base64(verifier) base64(salt) username gNid userinfo(optional) where the flag can be 'V' (valid) or 'R' (revoked). Note that the base64 encoding used here is non-standard so it is recommended to use openssl-srp(1) to generate this file.

The SRP_VBASE_add0_user() function adds the user_pwd verifier information to the vb structure. See SRP_user_pwd_new(3) to create and populate this record. The library takes ownership of user_pwd, it should not be freed by the caller.

The SRP_VBASE_get1_by_user() function returns the password info for the user whose username matches username. It replaces the deprecated SRP_VBASE_get_by_user(). If no matching user is found but a seed_key and default gN parameters have been set, dummy authentication information is generated from the seed_key, allowing the server to hide the fact that it doesn't have a verifier for a particular username. When using SRP as a TLS authentication mechanism, this will cause the handshake to proceed normally but the first client will be rejected with a "bad_record_mac" alert, as if the password was incorrect. If no matching user is found and the seed_key is not set, NULL is returned. Ownership of the returned pointer is released to the caller, it must be freed with SRP_user_pwd_free().

RETURN VALUES
SRP_VBASE_init() returns SRP_NO_ERROR (0) on success and a positive value on failure. The error codes are SRP_ERR_OPEN_FILE if the file could not be opened, SRP_ERR_VBASE_INCOMPLETE_FILE if the file could not be parsed, SRP_ERR_MEMORY on memory allocation failure and SRP_ERR_VBASE_BN_LIB for invalid decoded parameter values.

SRP_VBASE_add0_user() returns 1 on success and 0 on failure.

SEE ALSO
openssl-srp(1), SRP_create_verifier(3), SRP_user_pwd_new(3), SSL_CTX_set_srp_password(3)

HISTORY
The SRP_VBASE_add0_user() function was added in OpenSSL 3.0.

All other functions were added in OpenSSL 1.0.1.

COPYRIGHT
Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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>.