ID: 28525 Updated by: [EMAIL PROTECTED] Reported By: pickett at sumu dot org -Status: Open +Status: Closed Bug Type: *Math Functions PHP Version: 4.3.7RC1 New Comment:
This bug has been fixed in CVS. Snapshots of the sources are packaged every three hours; this change will be in the next snapshot. You can grab the snapshot at http://snaps.php.net/. Thank you for the report, and for helping us make PHP better. Previous Comments: ------------------------------------------------------------------------ [2004-06-09 16:02:04] pickett at sumu dot org Since I think I failed to explain the problem with just a simple gmp_powm() call, here's the entire diffie hellman implementation: $x = "0x98dd1dc9405f6d49b3ede0b8fb59d4db"; // random $y = "0x950ba32bc15861f13fe579b29a329ae3"; // random $n = "0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF"; // prime (ISAKMP/Oakley group1) $g = "0x2"; // generator for $n $X = gmp_powm($g, $x, $n); $Y = gmp_powm($g, $y, $n); $keyX = gmp_powm($X, $y, $n); $keyY = gmp_powm($Y, $x, $n); var_dump(gmp_strval($keyX, 16)); var_dump(gmp_strval($keyY, 16)); var_dump(gmp_cmp($keyX, $keyY)); Now, with php 4.3.4 and earlier the above code worked fine, but with 4.3.6 and later it fails (all gmp_powm() calls return false). There is no way to express $n as a normal php integer, but gmp_powm() still tries to convert it into one just to see if it is zero (and believes it is, as it starts with 0x...). Using gmp_sgn(*gmpnum_mod) to check if it is zero will work on large numbers, and is probably faster as well since it is a macro that just checks for _mp_size in the gmp mpz structure. The workaround is simple, just gmp_init() the modulo first, but I believe this still is a bug that should be fixed. ------------------------------------------------------------------------ [2004-05-28 11:59:57] pickett at sumu dot org Here's a fix --- php-4.3.7RC1/ext/gmp/gmp.c 2004-02-16 17:13:49.000000000 +0200 +++ php-4.3.7RC1/ext/gmp/gmp.c 2004-05-28 12:56:59.000000000 +0300 @@ -830,8 +830,7 @@ } FETCH_GMP_ZVAL(gmpnum_mod, mod_arg); - convert_to_long_ex(mod_arg); - if (!Z_LVAL_PP(mod_arg)) { + if(mpz_cmp_ui(*gmpnum_mod, 0) == 0) { RETURN_FALSE; } ------------------------------------------------------------------------ [2004-05-26 19:39:50] pickett at sumu dot org I used "0x1" here for brevity. In real world I use gmp_powm() for diffie-hellman key exchange with vastly larger numbers that can't be represented as normal integers in php. ------------------------------------------------------------------------ [2004-05-26 19:24:09] [EMAIL PROTECTED] Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php Do not pass hex numbers as strings. var_dump(gmp_powm(0x1, 0x1, 0x1)); works fine. ------------------------------------------------------------------------ [2004-05-26 11:08:10] pickett at sumu dot org Description: ------------ Fix for bug #27172 broke hexadecimal string modulos for gmp_powm(). Reproduce code: --------------- var_dump(gmp_powm("0x1", "0x1", "0x1")) Expected result: ---------------- resource(4) of type (GMP integer) Actual result: -------------- bool(false) ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=28525&edit=1
