Major pgcrypto changes:

of password-based encryption from RFC2440 (OpenPGP).

The goal of this code is to be more featureful encryption solution
than current encrypt(), which only functionality is running cipher
over data.

Compared to encrypt(), pgp_encrypt() does following:

* It uses the equvialent of random Inital Vector to get cipher
  into random state before it processes user data
* Stores SHA-1 of the data into result so any modification
  will be detected.
* Remembers if data was text or binary - thus it can decrypt
  to/from text data.  This was a major nuisance for encrypt().
* Stores info about used algorithms with result, so user needs
  not remember them - more user friendly!
* Uses String2Key algorithms (similar to crypt()) with random salt
  to generate full-length binary key to be used for encrypting.
* Uses standard format for data - you can feed it to GnuPG, if needed.

Optional features (off by default):

* Can use separate session key - user data will be encrypted
  with totally random key, which will be encrypted with S2K
  generated key and attached to result.
* Data compression with zlib.
* Can convert between CRLF<->LF line-endings - to get fully
  RFC2440-compliant behaviour.  This is off by default as
  pgcrypto does not know the line-endings of user data.

Interface is simple:


    pgp_encrypt(data text, key text) returns bytea
    pgp_decrypt(data text, key text) returns text
    pgp_encrypt_bytea(data bytea, key text) returns bytea
    pgp_decrypt_bytea(data bytea, key text) returns bytea

To change parameters (cipher, compression, mdc):

    pgp_encrypt(data text, key text, parms text) returns bytea
    pgp_decrypt(data text, key text, parms text) returns text
    pgp_encrypt_bytea(data bytea, key text, parms text) returns bytea
    pgp_decrypt_bytea(data bytea, key text, parms text) returns bytea

Parameter names I lifted from gpg:

   pgp_encrypt('message', 'key', 'compress-algo=1,cipher-algo=aes256')

For text data, pgp_encrypt simply encrypts the PostgreSQL internal data.

This maps to RFC2440 data type 't' - 'extenally specified encoding'.
But this may cause problems if data is dumped and reloaded into database
which as different internal encoding.  My next goal is to implement data
type 'u' - which means data is in UTF-8 encoding by converting internal
encoding to UTF-8 and back.  And there wont be any compatibility
problems with current code, I think its ok to submit this without UTF-8
encoding by converting internal encoding to UTF-8 and back.  And there
wont be any compatibility problems with current code, I think its ok to
submit this without UTF-8 support.


Here is v4 of PGP encrypt.  This depends on previously sent
Fortuna-patch, as it uses the px_add_entropy function.

- New function: pgp_key_id() for finding key id's.
- Add SHA1 of user data and key into RNG pools.  We need to get
  randomness from somewhere, and it is in user best interests
  to contribute.
- Regenerate pgp-armor test for SQL_ASCII database.
- Cleanup the key handling so that the pubkey support is less
  hackish.

Marko Kreen
This commit is contained in:
Bruce Momjian 2005-07-10 03:57:55 +00:00
parent 4fcf8b11ff
commit 73e2431817
5 changed files with 408 additions and 17 deletions

View File

@ -1,23 +1,35 @@
#
# $PostgreSQL: pgsql/contrib/pgcrypto/Makefile,v 1.19 2005/07/10 03:55:28 momjian Exp $
# $PostgreSQL: pgsql/contrib/pgcrypto/Makefile,v 1.20 2005/07/10 03:57:55 momjian Exp $
#
INT_SRCS = md5.c sha1.c sha2.c internal.c blf.c rijndael.c \
fortuna.c random.c
fortuna.c random.c pgp-mpi-internal.c
INT_TESTS = sha2
OSSL_SRCS = openssl.c
OSSL_SRCS = openssl.c pgp-mpi-openssl.c
OSSL_TESTS = des 3des cast5
ZLIB_OFF_CFLAGS = -DDISABLE_ZLIB
ZLIB_TST = pgp-compression
ZLIB_OFF_TST = pgp-zlib-DISABLED
PUBENC_ON = pgp-pubkey-decrypt pgp-pubkey-encrypt pgp-info
PUBENC_OFF = pgp-pubkey-DISABLED
CF_SRCS = $(if $(subst no,,$(with_openssl)), $(OSSL_SRCS), $(INT_SRCS))
CF_TESTS = $(if $(subst no,,$(with_openssl)), $(OSSL_TESTS), $(INT_TESTS))
CF_CFLAGS =
CF_CFLAGS = $(if $(subst yes,,$(with_zlib)), $(ZLIB_OFF_CFLAGS))
CF_PGP_TESTS = $(if $(subst no,,$(with_zlib)), $(ZLIB_TST), $(ZLIB_OFF_TST)) \
$(if $(subst no,,$(with_openssl)), $(PUBENC_ON), $(PUBENC_OFF))
PG_CPPFLAGS = $(CF_CFLAGS)
SRCS = pgcrypto.c px.c px-hmac.c px-crypt.c misc.c \
crypt-gensalt.c crypt-blowfish.c crypt-des.c \
crypt-md5.c $(CF_SRCS)
crypt-md5.c $(CF_SRCS) \
mbuf.c pgp.c pgp-armor.c pgp-cfb.c pgp-compress.c \
pgp-decrypt.c pgp-encrypt.c pgp-info.c pgp-mpi.c \
pgp-pubdec.c pgp-pubenc.c pgp-pubkey.c pgp-s2k.c \
pgp-pgsql.c
MODULE_big = pgcrypto
OBJS = $(SRCS:.c=.o)
@ -27,7 +39,8 @@ EXTRA_CLEAN = gen-rtab
REGRESS = init md5 sha1 hmac-md5 hmac-sha1 blowfish rijndael \
$(CF_TESTS) \
crypt-des crypt-md5 crypt-blowfish crypt-xdes
crypt-des crypt-md5 crypt-blowfish crypt-xdes \
pgp-armor pgp-decrypt pgp-encrypt $(CF_PGP_TESTS)
ifdef USE_PGXS

View File

@ -11,10 +11,10 @@ Edit makefile, if you want to use any external library.
NB! Default randomness source is libc random() function. This
is so only to get pgcrypto build everywhere. Randomness is
needed for gen_salt() function. So if you plan using it, you
should definitely change that by editing Makefile. You should
be using urandom device if your OS supports it, otherwise link
pgcrypto against OpenSSL library and use its PRNG.
needed for gen_salt() and pgp_encrypt() functions. So if you plan
using those, you should definitely change that by editing Makefile.
You can should use urandom device if your OS supports it, otherwise
link pgcrypto against OpenSSL library and use its PRNG.
After editing Makefile:
@ -108,6 +108,161 @@ gen_salt(type::text, rounds::int4)::text
For maximum security, you should choose the 'bf' crypt
and use maximum number of rounds you can still tolerate.
armor(bytea)::text
dearmor(text)::bytea
Those wrap/unwrap data into PGP Ascii Armor which
is basically Base64 with CRC and additional formatting.
pgp_sym_encrypt(data::text, key::text)::bytea
pgp_sym_encrypt(data::text, key::text, arg::text)::bytea
pgp_sym_encrypt_bytea(data::bytea, key::text)::bytea
pgp_sym_encrypt_bytea(data::bytea, key::text, arg::text)::bytea
pgp_sym_decrypt(data::bytea, key::text)::text
pgp_sym_decrypt(data::bytea, key::text, arg::text)::text
pgp_sym_decrypt_bytea(data::text, key::text)::bytea
pgp_sym_decrypt_bytea(data::text, key::text, arg::text)::bytea
Encrypt data into OpenPGP Symmetrically Encrypted Data
message. And decrypt it from it.
Note that the pgp_sym_encrypt_bytea functions tag the data
as binary, as the pgp_sym_encrypt will tag the data as text.
You can not decrypt the binary data as text. But you can
decrypt text data as binary. This rule avoids having
broken textual data in PostgreSQL.
Both encrypt and decrypt accept also third argument, which
is parameters to the function in following format:
parm=val[,parm=val]...
Example:
select pgp_sym_encrypt('data', 'psw',
'compress-algo=2, unicode-mode=1');
Accepted parameters are:
cipher-algo: bf, aes, aes128, aes192, aes256
Cipher algorithm to use. OpenSSL gives additional algorithms:
3des, cast5
Default: aes128
compress-algo: 0, 1, 2
Which compression algorithm to use.
0 - no compression
1 - ZIP compression
2 - ZLIB compression [=ZIP plus meta-data and block-CRC's]
Default: 0
compress-level: 0, 1-9
How much to compress. Bigger level compresses smaller
but also slower. 0 disables compression.
Default: 6
convert-crlf: 0, 1
Whether to convert \n into \r\n when encrypting and
\r\n to \n when decrypting. RFC2440 specifies that
text packets should use "\r\n" line-feeds.
Use this to get fully RFC-compliant behaviour.
Default: 0
disable-mdc: 0, 1
Do not protect data with SHA-1. Note that SHA-1 protected
packet is from upcoming update to RFC2440. (Currently at
version RFC2440bis-13.) You need to disable it if you need
compatibility with ancient PGP products. Recent gnupg.org
and pgp.com software supports it fine.
Default: 0
enable-session-key: 0, 1
Use separate session key.
Default: 0
s2k-mode: 0, 1, 3
Which S2K algorithm to use. 0 is dangerous - without salt.
Default: 3
s2k-digest-algo: md5, sha1
Which digest algorithm to use in S2K calculation.
Default: SHA-1
s2k-cipher-algo: bf, aes, aes128, aes192, aes256
Which cipher to use for encrypting separate session key.
Default: same as cipher-algo.
unicode-mode: 0, 1
Whether to convert textual data from database internal
encoding to UTF-8 and back.
Default: 0
Only 'convert-crlf' applies to both encrypt and decrypt,
all others apply only to encrypt - decrypt gets the
settings from PGP data.
pgp_pub_encrypt(data::text, key::bytea)::bytea
pgp_pub_encrypt(data::text, key::bytea, arg::text)::bytea
pgp_pub_encrypt_bytea(data::bytea, bytea::text)::bytea
pgp_pub_encrypt_bytea(data::bytea, bytea::text, arg::text)::bytea
pgp_pub_decrypt(data::bytea, key::bytea)::text
pgp_pub_decrypt(data::bytea, key::bytea, psw::text)::text
pgp_pub_decrypt(data::bytea, key::bytea, psw::text, arg::text)::text
pgp_pub_decrypt_bytea(data::text, key::bytea)::bytea
pgp_pub_decrypt_bytea(data::text, key::bytea, psw::text)::bytea
pgp_pub_decrypt_bytea(data::text, key::bytea, psw::text, arg::bytea)::bytea
Encrypt data into OpenPGP Public-Key Encrypted Data
message. And decrypt it from it. The arg parameter is
described in pgp_sym_* section.
The key must be a public-key packet for pgp_pub_encrypt
functions and a secret key packet for pgp_pub_decrypt
functions. Trying to encrypt with secret key gives a error.
While being technically possible, it is probably a sign of
user error and leaking secret keys.
Here is a example how to generate them:
Generate a new key:
gpg --gen-key
You need to pick "DSA and Elgamal" key type, others
are sign-only.
List keys:
gpg --list-secret-keys
Export ascii-armored public key:
gpg -a --export KEYID > public.key
Export ascii-armored secret key:
gpg -a --export-secret-keys KEYID > secret.key
You need to use dearmor() on them before giving giving
them to pgp_pub_* functions. Ofcourse, if you can handle
binary data, you can drop "-a" from gpg.
pgp_key_id(key / data)
It shows you either key ID if given PGP public or secret
key. Or it gives the key ID what was used for encrypting
the data, if given encrypted data.
It can return 2 special key ID's:
SYMKEY - it got symmetrically encrypted data.
ANYKEY - the data packet key ID is clear. That means
you should try all you secret keys on it.
encrypt(data::bytea, key::bytea, type::text)::bytea
decrypt(data::bytea, key::bytea, type::text)::bytea
encrypt_iv(data::bytea, key::bytea, iv::bytea, type::text)::bytea

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@ -71,4 +71,141 @@ RETURNS bool
AS 'MODULE_PATHNAME', 'pg_cipher_exists'
LANGUAGE 'C' IMMUTABLE STRICT;
--
-- pgp_sym_encrypt(data, key)
--
CREATE OR REPLACE FUNCTION pgp_sym_encrypt(text, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_sym_encrypt_text'
LANGUAGE 'C' STRICT;
CREATE OR REPLACE FUNCTION pgp_sym_encrypt_bytea(bytea, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_sym_encrypt_bytea'
LANGUAGE 'C' STRICT;
--
-- pgp_sym_encrypt(data, key, args)
--
CREATE OR REPLACE FUNCTION pgp_sym_encrypt(text, text, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_sym_encrypt_text'
LANGUAGE 'C' STRICT;
CREATE OR REPLACE FUNCTION pgp_sym_encrypt_bytea(bytea, text, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_sym_encrypt_bytea'
LANGUAGE 'C' STRICT;
--
-- pgp_sym_decrypt(data, key)
--
CREATE OR REPLACE FUNCTION pgp_sym_decrypt(bytea, text)
RETURNS text
AS 'MODULE_PATHNAME', 'pgp_sym_decrypt_text'
LANGUAGE 'C' IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION pgp_sym_decrypt_bytea(bytea, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_sym_decrypt_bytea'
LANGUAGE 'C' IMMUTABLE STRICT;
--
-- pgp_sym_decrypt(data, key, args)
--
CREATE OR REPLACE FUNCTION pgp_sym_decrypt(bytea, text, text)
RETURNS text
AS 'MODULE_PATHNAME', 'pgp_sym_decrypt_text'
LANGUAGE 'C' IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION pgp_sym_decrypt_bytea(bytea, text, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_sym_decrypt_bytea'
LANGUAGE 'C' IMMUTABLE STRICT;
--
-- pgp_pub_encrypt(data, key)
--
CREATE OR REPLACE FUNCTION pgp_pub_encrypt(text, bytea)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_pub_encrypt_text'
LANGUAGE 'C' STRICT;
CREATE OR REPLACE FUNCTION pgp_pub_encrypt_bytea(bytea, bytea)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_pub_encrypt_bytea'
LANGUAGE 'C' STRICT;
--
-- pgp_pub_encrypt(data, key, args)
--
CREATE OR REPLACE FUNCTION pgp_pub_encrypt(text, bytea, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_pub_encrypt_text'
LANGUAGE 'C' STRICT;
CREATE OR REPLACE FUNCTION pgp_pub_encrypt_bytea(bytea, bytea, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_pub_encrypt_bytea'
LANGUAGE 'C' STRICT;
--
-- pgp_pub_decrypt(data, key)
--
CREATE OR REPLACE FUNCTION pgp_pub_decrypt(bytea, bytea)
RETURNS text
AS 'MODULE_PATHNAME', 'pgp_pub_decrypt_text'
LANGUAGE 'C' IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION pgp_pub_decrypt_bytea(bytea, bytea)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_pub_decrypt_bytea'
LANGUAGE 'C' IMMUTABLE STRICT;
--
-- pgp_pub_decrypt(data, key, psw)
--
CREATE OR REPLACE FUNCTION pgp_pub_decrypt(bytea, bytea, text)
RETURNS text
AS 'MODULE_PATHNAME', 'pgp_pub_decrypt_text'
LANGUAGE 'C' IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION pgp_pub_decrypt_bytea(bytea, bytea, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_pub_decrypt_bytea'
LANGUAGE 'C' IMMUTABLE STRICT;
--
-- pgp_pub_decrypt(data, key, psw, arg)
--
CREATE OR REPLACE FUNCTION pgp_pub_decrypt(bytea, bytea, text, text)
RETURNS text
AS 'MODULE_PATHNAME', 'pgp_pub_decrypt_text'
LANGUAGE 'C' IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION pgp_pub_decrypt_bytea(bytea, bytea, text, text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pgp_pub_decrypt_bytea'
LANGUAGE 'C' IMMUTABLE STRICT;
--
-- PGP key ID
--
CREATE OR REPLACE FUNCTION pgp_key_id(bytea)
RETURNS text
AS 'MODULE_PATHNAME', 'pgp_key_id_w'
LANGUAGE 'C' IMMUTABLE STRICT;
--
-- pgp armor
--
CREATE OR REPLACE FUNCTION armor(bytea)
RETURNS text
AS 'MODULE_PATHNAME', 'pg_armor'
LANGUAGE 'C' IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION dearmor(text)
RETURNS bytea
AS 'MODULE_PATHNAME', 'pg_dearmor'
LANGUAGE 'C' IMMUTABLE STRICT;

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@ -26,7 +26,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $PostgreSQL: pgsql/contrib/pgcrypto/px.c,v 1.11 2005/03/21 05:22:14 neilc Exp $
* $PostgreSQL: pgsql/contrib/pgcrypto/px.c,v 1.12 2005/07/10 03:57:55 momjian Exp $
*/
#include <postgres.h>
@ -57,6 +57,37 @@ static const struct error_desc px_err_list[] = {
{PXE_BAD_SALT_ROUNDS, "Incorrect number of rounds"},
{PXE_MCRYPT_INTERNAL, "mcrypt internal error"},
{PXE_NO_RANDOM, "No strong random source"},
{PXE_PGP_CORRUPT_DATA, "Wrong key or corrupt data"},
{PXE_PGP_CORRUPT_ARMOR, "Corrupt ascii-armor"},
{PXE_PGP_UNSUPPORTED_COMPR, "Unsupported compression algorithm"},
{PXE_PGP_UNSUPPORTED_CIPHER, "Unsupported cipher algorithm"},
{PXE_PGP_UNSUPPORTED_HASH, "Unsupported digest algorithm"},
{PXE_PGP_COMPRESSION_ERROR, "Compression error"},
{PXE_PGP_NOT_TEXT, "Not text data"},
{PXE_PGP_UNEXPECTED_PKT, "Unexpected packet in key data"},
{PXE_PGP_NO_BIGNUM,
"public-key functions disabled - "
"pgcrypto needs OpenSSL for bignums"},
{PXE_PGP_MATH_FAILED, "Math operation failed"},
{PXE_PGP_SHORT_ELGAMAL_KEY, "Elgamal keys must be at least 1024 bits long"},
{PXE_PGP_RSA_UNSUPPORTED, "pgcrypto does not support RSA keys"},
{PXE_PGP_UNKNOWN_PUBALGO, "Unknown public-key encryption algorithm"},
{PXE_PGP_WRONG_KEYID, "Data is not encrypted with this key"},
{PXE_PGP_MULTIPLE_KEYS,
"Several keys given - pgcrypto does not handle keyring"},
{PXE_PGP_EXPECT_PUBLIC_KEY, "Refusing to encrypt with secret key"},
{PXE_PGP_EXPECT_SECRET_KEY, "Cannot decrypt with public key"},
{PXE_PGP_NOT_V4_KEYPKT, "Only V4 key packets are supported"},
{PXE_PGP_KEYPKT_CORRUPT, "Corrupt key packet"},
{PXE_PGP_NO_USABLE_KEY, "No usable key found (expecting Elgamal key)"},
{PXE_PGP_NEED_SECRET_PSW, "Need password for secret key"},
{PXE_PGP_BAD_S2K_MODE, "Bad S2K mode"},
{PXE_PGP_UNSUPPORTED_PUBALGO, "Unsupported public key algorithm"},
{PXE_PGP_MULTIPLE_SUBKEYS, "Several subkeys not supported"},
/* fake this as PXE_PGP_CORRUPT_DATA */
{PXE_MBUF_SHORT_READ, "Corrupt data"},
{0, NULL},
};
@ -82,6 +113,25 @@ px_resolve_alias(const PX_Alias * list, const char *name)
return name;
}
static void (*debug_handler)(const char *) = NULL;
void px_set_debug_handler(void (*handler)(const char *))
{
debug_handler = handler;
}
void px_debug(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
if (debug_handler) {
char buf[512];
vsnprintf(buf, sizeof(buf), fmt, ap);
debug_handler(buf);
}
va_end(ap);
}
/*
* combo - cipher + padding (+ checksum)
*/

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@ -26,7 +26,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $PostgreSQL: pgsql/contrib/pgcrypto/px.h,v 1.13 2005/07/10 03:55:28 momjian Exp $
* $PostgreSQL: pgsql/contrib/pgcrypto/px.h,v 1.14 2005/07/10 03:57:55 momjian Exp $
*/
#ifndef __PX_H
@ -42,19 +42,20 @@
#error BYTE_ORDER must be defined as LITTLE_ENDIAN or BIG_ENDIAN
#endif
/* keep debug messages? */
#define PX_DEBUG
/* a way to disable palloc
* - useful if compiled into standalone
*/
#ifndef PX_OWN_ALLOC
#define px_alloc(s) palloc(s)
#define px_realloc(p, s) repalloc(p, s)
#define px_free(p) pfree(p)
#else
void *px_alloc(size_t s);
void *px_realloc(void *p, size_t s);
void px_free(void *p);
#endif
/* max len of 'type' parms */
@ -85,6 +86,34 @@ void px_free(void *p);
#define PXE_MCRYPT_INTERNAL -16
#define PXE_NO_RANDOM -17
#define PXE_MBUF_SHORT_READ -50
#define PXE_PGP_CORRUPT_DATA -100
#define PXE_PGP_CORRUPT_ARMOR -101
#define PXE_PGP_UNSUPPORTED_COMPR -102
#define PXE_PGP_UNSUPPORTED_CIPHER -103
#define PXE_PGP_UNSUPPORTED_HASH -104
#define PXE_PGP_COMPRESSION_ERROR -105
#define PXE_PGP_NOT_TEXT -106
#define PXE_PGP_UNEXPECTED_PKT -107
#define PXE_PGP_NO_BIGNUM -108
#define PXE_PGP_MATH_FAILED -109
#define PXE_PGP_SHORT_ELGAMAL_KEY -110
#define PXE_PGP_RSA_UNSUPPORTED -111
#define PXE_PGP_UNKNOWN_PUBALGO -112
#define PXE_PGP_WRONG_KEYID -113
#define PXE_PGP_MULTIPLE_KEYS -114
#define PXE_PGP_EXPECT_PUBLIC_KEY -115
#define PXE_PGP_EXPECT_SECRET_KEY -116
#define PXE_PGP_NOT_V4_KEYPKT -117
#define PXE_PGP_KEYPKT_CORRUPT -118
#define PXE_PGP_NO_USABLE_KEY -119
#define PXE_PGP_NEED_SECRET_PSW -120
#define PXE_PGP_BAD_S2K_MODE -121
#define PXE_PGP_UNSUPPORTED_PUBALGO -122
#define PXE_PGP_MULTIPLE_SUBKEYS -123
typedef struct px_digest PX_MD;
typedef struct px_alias PX_Alias;
typedef struct px_hmac PX_HMAC;
@ -103,7 +132,7 @@ struct px_digest
union
{
unsigned code;
const void *ptr;
void *ptr;
} p;
};
@ -178,6 +207,13 @@ const char *px_strerror(int err);
const char *px_resolve_alias(const PX_Alias * aliases, const char *name);
void px_set_debug_handler(void (*handler)(const char *));
#ifdef PX_DEBUG
void px_debug(const char *fmt, ...);
#else
#define px_debug(...)
#endif
#define px_md_result_size(md) (md)->result_size(md)
#define px_md_block_size(md) (md)->block_size(md)
#define px_md_reset(md) (md)->reset(md)