LIBNETPGPVERIFY(3) | Library Functions Manual | LIBNETPGPVERIFY(3) |
libnetpgpverify
—
#include <netpgp/verify.h>
int
pgpv_new
(void);
int
pgpv_new_cursor
(void);
int
pgpv_read_pubring
(pgpv_t *pgp,
const void *keyring, ssize_t
size);
int
pgpv_read_ssh_pubkeys
(pgpv_t
*pgp, const void *keyring,
ssize_t size);
size_t
pgpv_verify
(pgpv_cursor_t
*cursor, pgpv_t *pgp, const void
*ptr, ssize_t size);
size_t
pgpv_get_verified
(pgpv_cursor_t
*cursor, size_t cookie, char
**ret);
size_t
pgpv_get_cursor_element
(pgpv_cursor_t
*cursor, size_t element);
size_t
pgpv_dump
(pgpv_t *pgp,
char **data);
size_t
pgpv_get_entry
(pgpv_t *pgp,
unsigned ent, char **ret,
const char *modifiers);
int64_t
pgpv_get_cursor_num
(pgpv_t *pgp,
const char *field);
char *
pgpv_get_cursor_str
(pgpv_t *pgp,
const char *field);
int
pgpv_close
(pgpv_t *pgp);
libnetpgpverify
is a small library which will verify a
digital signature on a text or binary document. It has been kept deliberately
small and only uses compression libraries to function.
PGP messages, including key rings, are made up of PGP packets,
defined in RFC 4880. To match a digital signature, the public key of the
signer must be located in a public key ring. This library has enough
functionality to parse a pubkey keyring, using
pgpv_read_pubring
() to read the public keys of
trusted identities, and to read files or memory which has already been
signed. SSH public keys can also be used for signature verification by using
the pgpv_read_ssh_pubkeys
() function. Please note
that the creation date of the signature key will show up as January 1st
1970, due to the fact that the creation date of the key is not encoded
anywhere for an ssh key, whilst it is an inherent part of the PGP
fingerprint. In order that the correct fingerprint is used, the key creation
date is forced to 0.
The pgpv_verify
() function is used to
verify the signature, either on data, or on memory. To signal to
pgpv_verify
() to read a file and verify it, the
size
argument should be set to
-1
whilst a positive size signals that the pointer
value should be that of signed memory. pgpv_verify
()
returns a cookie if the ignature was verified, or 0 if it did not. This
cookie can subsequently be used to retrieve the data which was verified.
If the signature does match, then the file or memory can be considered as being verified as being unmodified and unchanged, integrally sound.
Signatures have validity dates on them, and it is possible for a
signature to have expired when it is being checked. If for any reason the
signature does not match, then the reason for not verifying the signature
will be stored in the why
buffer in the
pgpv_cursor_t
structure.
Occasionally, the memory or contents of the file which matched the
signature will be needed, rather than a boolean value of whether it was
verified. To do this, the pgpv_get_verified
()
function is used. Arguments to pgpv_get_verified
()
are the cookie returned from the verification, and a buffer allocated for
the returned data and its size. If an error occurs, or the signature is not
verified, a zero value is returned for the size.
libnetpgpverify
stores the starts of the data of all
verified matches, and so the entry number argument is the index of the
occurrence of verification. The first match will have an entry number of 0,
the second 1, and so on.
The pgpv_close
() function is used to clean
up after all matching and verification has taken place. It frees and
de-allocates all resources used in the verification of the signature.
The program used for signing may encode into base64 encoding, and
it may also use embedded compression to make the output smaller than it
would otherwise be. This is handled automatically by
libnetpgpverify
libnetpgpverify
utility is designed to conform to
IETF RFC 4880.
libnetpgpverify
library first appeared in
NetBSD 7.0.
June 26, 2016 | NetBSD 9.2 |