LIBNETPGP(3) | Library Functions Manual | LIBNETPGP(3) |
libnetpgp
—
#include <netpgp.h>
The following functions relate to initialisations and
finalisations:
int
netpgp_init
(netpgp_t
*netpgp);
int
netpgp_end
(netpgp_t
*netpgp);
The following functions are for debugging, reflection and
information:
int
netpgp_set_debug
(const char
*filename);
int
netpgp_get_debug
(const char
*filename);
int
netpgp_get_info
(const char
*type);
int
netpgp_list_packets
(netpgp_t
*netpgp, char *filename, int
armour, char *pubringname);
The following functions are for variable management:
int
netpgp_setvar
(netpgp_t *netpgp,
const char *name, const char
*value);
char *
netpgp_getvar
(netpgp_t *netpgp,
const char *name);
int
netpgp_incvar
(netpgp_t *netpgp,
const char *name, const int
delta);
int
netpgp_unsetvar
(netpgp_t
*netpgp, const char *name);
The following function sets the home directory:
int
netpgp_set_homedir
(netpgp_t
*netpgp, char *homedir, char
*subdir, const int quiet);
The following functions are used for key management:
int
netpgp_list_keys
(netpgp_t
*netpgp, const int printsigs);
int
netpgp_list_keys_json
(netpgp_t
*netpgp, char **json, const int
psigs);
int
netpgp_match_keys
(netpgp_t
*netpgp, char *name, const char
*fmt, void *vp, const int
psigs);
int
netpgp_match_keys_json
(netpgp_t
*netpgp, char **json, char
*name, const char *fmt, const
int psigs);
int
netpgp_match_pubkeys
(netpgp_t
*netpgp, char *name, void
*vp);
int
netpgp_find_key
(netpgp_t
*netpgp, char *userid);
char *
netpgp_get_key
(netpgp_t *netpgp,
const char *name, const char
*fmt);
int
netpgp_export_key
(netpgp_t
*netpgp, char *userid);
int
netpgp_import_key
(netpgp_t
*netpgp, char *file);
int
netpgp_generate_key
(netpgp_t
*netpgp, char *userid, int
numbits);
int
netpgp_validate_sigs
(netpgp_t
*netpgp);
int
netpgp_format_json
(void *vp,
const char *json, const int
psigs);
The following functions are used for file management:
int
netpgp_encrypt_file
(netpgp_t
*netpgp, const char *userid,
const char *filename, char *out,
int armored);
int
netpgp_decrypt_file
(netpgp_t
*netpgp, const char *filename,
char *out, int armored);
int
netpgp_sign_file
(netpgp_t
*netpgp, const char *userid,
const char *filename, char *out,
int armored, int cleartext,
int detached);
int
netpgp_verify_file
(netpgp_t
*netpgp, const char *in, const
char *out, int armored);
The following functions are used for memory signing and
encryption:
int
netpgp_encrypt_memory
(netpgp_t
*netpgp, const char *userid,
void *in, const size_t insize,
char *out, size_t outsize,
int armored);
int
netpgp_decrypt_memory
(netpgp_t
*netpgp, const void *input,
const size_t insize, char *out,
size_t outsize, const int
armored);
int
netpgp_sign_memory
(netpgp_t
*netpgp, const char *userid,
char *mem, size_t size,
char *out, size_t outsize,
const unsigned armored, const unsigned
cleartext);
int
netpgp_verify_memory
(netpgp_t
*netpgp, const void *in, const
size_t insize, void *out, size_t
outsize, const int armored);
libnetpgp
is a library interface to enable digital
signatures to be created and verified, and also for files and memory to be
encrypted and decrypted. Functions are also provided for management of user
keys.
The library uses functions from the openssl library for multi-precision integer arithmetic, and for RSA and DSA key signing and verification, encryption and decryption.
Normal operation sees the libnetpgp
process be initialised using the netpgp_init
()
function, which will set up the public and private keyrings, as well as set
the user identity in the userid member of the
netpgp_t
structure. These are set using the
netpgp_setvar
() function and unset using the
netpgp_unsetvar
() function. If no public key ring
file is set, initial values will be taken from those in the
.gnupg/pubring.gpg file in the user's home
directory. Similarly, if no secret key ring file is set, initial values will
be taken from those in the .gnupg/secring.gpg file
in the user's home directory. The user identity is obtained from the
userid
environment variable, or failing that, the
value of the “default-key” setting from
.gnupg/gpg.conf file in the user's home directory is
used. The netpgp_init
() function returns 1 on
success, 0 on failure.
To list all the keys in a keyring, the
netpgp_list_keys
() function is used. To list all the
keys in a keyring as a JSON encoded string, the
netpgp_list_keys_json
() function is used. To find
and list keys in a keyring, the netpgp_match_keys
()
function is used. To find and list keys in a keyring, output as a JSON
encoded string, the netpgp_match_keys_json
()
function is used. To find and list keys in a better suited machine-readble
format, such as for redirection to other parsing engines, the
netpgp_match_pubkeys
() function is used. The
signature subkey fields can also be displayed using this function.
The home directory is specified as an internal variable, and its
existence is checked using the netpgp_set_homedir
()
function. This function can operate in a verbose or quiet manner, depending
on the value of the argument provided. If the subdirectory argument is
provided, this subdirectory is appended to the home directory in order to
search for the keyrings.
To print key information from a JSON encoded string, stored in a
file, the netpgp_format_json
() function is used.
To validate the signature of keys in a public key keyring, the
netpgp_validate_sigs
() function is used.
To export a key, the netpgp_export_key
()
function is used. Output is sent to the standard output.
To import a key onto the public keyring, the
netpgp_import_key
() function is used. The name of
the file containing the key to be imported is provided as the filename
argument.
To generate a key, the
netpgp_generate_key
() function is used. It takes an
argument of the number of bits to use in the key. At the time that this
manual page was created (April 2009), the recommendations are that the bare
minimum key size of at least 2048 bits is used, and it would be much better
to use at least 4096 or 8192 bits. This situation should be monitored to
ensure that it does not go out of date.
Encryption, decryption, signing and verification of files are the
lifeblood of the libnetpgp
library. To encrypt a
file, the netpgp_encrypt_file
() function is used,
and the netpgp_decrypt_file
() function is used to
decrypt the results of the encryption. To sign a file, the
netpgp_sign_file
() function is used, and the
resulting signed file can be verified using the
netpgp_verify_file
() function.
netpgp_sign_memory
() is a function which
can sign an area of memory, and
netpgp_verify_memory
() verifies the digital
signature produced.
Internally, an encrypted or signed file is made up of
“packets” which hold information pertaining to the signature,
encryption method, and the data which is being protected. This information
can be displayed in a verbose manner using the
netpgp_list_packets
() function.
The netpgp_setvar
() and
netpgp_getvar
() functions are used to manage the
hash algorithm that is used with RSA signatures. These functions are general
purpose functions, and are used to set and retrieve values for internal
variables. For example, they can be used to set and to retrieve the value of
the user id which has been set, the home directory from which to find the
keyrings, the verbosity settings, and many more. The
netpgp_incvar
() function is used to add a numeric
increment to the internal variable. This incremental value can be negative.
It is primarily used to increase the verbosity settings.
In libnetpgp
files are encrypted using the
public key of the userid. The secret key is used to decrypt the results of
that encryption. Files are signed using the secret key of the userid. The
public key is used to verify that the file was signed, who signed the file,
and the date and time at which it was signed.
Some utility functions are also provided for debugging, and for
finding out version and maintainer information from calling programs. These
are the netpgp_set_debug
() and the
netpgp_get_debug
() functions (for getting verbose
debugging information on a per-source file basis).
The netpgp_get_info
() function returns the
version or maintainer information depending upon the
type argument. At the present time, two types are
defined: “version” and “maintainer”. The
maintainer information returned contains the name, email address, and PGP
short key id. A failure to present a known type
argument to netpgp_get_info
() will result in the
string “[unknown]” being returned.
libnetpgp
library first appeared in
NetBSD 6.0.
This manual page was written by Alistair Crooks.
May 10, 2018 | NetBSD 9.2 |