ext/gmp: Add gmp_powm_sec()

NEWS

@@ -12,6 +12,7 @@ PHP                                                                        NEWS
     declares a default value for the attribute). (iliaal)
 
 - GMP:
+  . Added gmp_powm_sec(). (Weilin Du)
   . Fixed GMP power and shift operators to reject GMP right operands outside
     the unsigned long range instead of silently truncating them. (Weilin Du)
   . Fixed GMP integer string parsing to reject strings containing NUL bytes

UPGRADING

@@ -265,6 +265,10 @@ PHP 8.6 UPGRADE NOTES
 - Fileinfo:
   . finfo_file() now works with remote streams.
 
+- GMP:
+  . Added gmp_powm_sec() for side-channel quiet modular exponentiation.
+    Requires GNU MP 5.0.0 or later.
+
 - Intl:
   . Added Locale::getDisplayKeyword() and Locale::getDisplayKeywordValue(),
     with the alias of locale_get_display_keyword() and
@@ -406,6 +410,9 @@ PHP 8.6 UPGRADE NOTES
 6. New Functions
 ========================================
 
+- GMP:
+  . gmp_powm_sec()
+
 - Intl:
   . grapheme_strrev()
     RFC: https://wiki.php.net/rfc/grapheme_strrev

ext/gmp/config.m4

@@ -22,6 +22,7 @@ if test "$PHP_GMP" != "no"; then
   LIBS="$LIBS $GMP_LIBS"
   gmp_check=no
   AC_CHECK_HEADER([gmp.h], [AC_CHECK_FUNC([__gmpz_rootrem], [gmp_check=yes])])
+  AC_CHECK_FUNCS([__gmpz_powm_sec])
   CFLAGS=$CFLAGS_SAVED
   LIBS=$LIBS_SAVED
 

ext/gmp/config.w32

@@ -5,6 +5,9 @@ ARG_WITH("gmp", "Include GNU MP support.", "no");
 if (PHP_GMP != "no") {
 	if (CHECK_LIB("mpir_a.lib", "gmp", PHP_GMP) &&
 		CHECK_HEADER("gmp.h", "CFLAGS_GMP", PHP_GMP +  ";" + PHP_PHP_BUILD + "\\include\\mpir")) {
+		if (GREP_HEADER("gmp.h", "mpz_powm_sec", PHP_GMP +  ";" + PHP_PHP_BUILD + "\\include\\mpir")) {
+			AC_DEFINE('HAVE___GMPZ_POWM_SEC', 1, "Define to 1 if GMP has the 'mpz_powm_sec' function.");
+		}
 		EXTENSION("gmp", "gmp.c", null, "/DZEND_ENABLE_STATIC_TSRMLS_CACHE=1");
 		PHP_INSTALL_HEADERS("ext/gmp", "php_gmp_int.h");
 		AC_DEFINE('HAVE_GMP', 1, "Define to 1 if the PHP extension 'gmp' is available.");

ext/gmp/gmp.c

@@ -1189,6 +1189,39 @@ ZEND_FUNCTION(gmp_powm)
 }
 /* }}} */
 
+#ifdef HAVE___GMPZ_POWM_SEC
+/* {{{ Raise base to power exp and take result modulo mod using a side-channel quiet algorithm */
+ZEND_FUNCTION(gmp_powm_sec)
+{
+	mpz_ptr gmpnum_base, gmpnum_exp, gmpnum_mod, gmpnum_result;
+
+	ZEND_PARSE_PARAMETERS_START(3, 3)
+		GMP_Z_PARAM_INTO_MPZ_PTR(gmpnum_base)
+		GMP_Z_PARAM_INTO_MPZ_PTR(gmpnum_exp)
+		GMP_Z_PARAM_INTO_MPZ_PTR(gmpnum_mod)
+	ZEND_PARSE_PARAMETERS_END();
+
+	if (mpz_sgn(gmpnum_exp) <= 0) {
+		zend_argument_value_error(2, "must be greater than 0");
+		RETURN_THROWS();
+	}
+
+	if (!mpz_cmp_ui(gmpnum_mod, 0)) {
+		zend_argument_error(zend_ce_division_by_zero_error, 3, "Modulo by zero");
+		RETURN_THROWS();
+	}
+
+	if (!mpz_odd_p(gmpnum_mod)) {
+		zend_argument_value_error(3, "must be odd");
+		RETURN_THROWS();
+	}
+
+	INIT_GMP_RETVAL(gmpnum_result);
+	mpz_powm_sec(gmpnum_result, gmpnum_base, gmpnum_exp, gmpnum_mod);
+}
+/* }}} */
+#endif
+
 /* {{{ Takes integer part of square root of a */
 ZEND_FUNCTION(gmp_sqrt)
 {

ext/gmp/gmp.stub.php

@@ -125,6 +125,10 @@ function gmp_pow(GMP|int|string $num, int $exponent): GMP {}
 
 function gmp_powm(GMP|int|string $num, GMP|int|string $exponent, GMP|int|string $modulus): GMP {}
 
+#ifdef HAVE___GMPZ_POWM_SEC
+function gmp_powm_sec(GMP|int|string $num, GMP|int|string $exponent, GMP|int|string $modulus): GMP {}
+#endif
+
 function gmp_perfect_square(GMP|int|string $num): bool {}
 
 function gmp_perfect_power(GMP|int|string $num): bool {}

ext/gmp/tests/bug80560.phpt

@@ -60,6 +60,9 @@ $functions2 = [
 $functions3 = [
     'gmp_powm',
 ];
+if (function_exists('gmp_powm_sec')) {
+    $functions3[] = 'gmp_powm_sec';
+}
 
 echo 'Explicit base with gmp_init:', \PHP_EOL;
 echo 'Hexadecimal', \PHP_EOL;

ext/gmp/tests/gmp_powm_sec.phpt

@@ -0,0 +1,46 @@
+--TEST--
+gmp_powm_sec()
+--EXTENSIONS--
+gmp
+--SKIPIF--
+<?php
+if (!function_exists('gmp_powm_sec')) {
+    die('skip gmp_powm_sec() is not available');
+}
+?>
+--FILE--
+<?php
+
+var_dump(gmp_strval(gmp_powm_sec(4, 13, 497)));
+var_dump(gmp_strval(gmp_powm_sec(gmp_init(7), gmp_init(3), gmp_init(13))));
+
+foreach ([0, -1] as $exp) {
+    try {
+        var_dump(gmp_powm_sec(4, $exp, 497));
+    } catch (\ValueError $e) {
+        echo $e->getMessage(), \PHP_EOL;
+    }
+}
+
+try {
+    var_dump(gmp_powm_sec(4, 13, 0));
+} catch (\DivisionByZeroError $e) {
+    echo $e->getMessage(), \PHP_EOL;
+}
+
+try {
+    var_dump(gmp_powm_sec(4, 13, 496));
+} catch (\ValueError $e) {
+    echo $e->getMessage(), \PHP_EOL;
+}
+
+echo "Done\n";
+?>
+--EXPECT--
+string(3) "445"
+string(1) "5"
+gmp_powm_sec(): Argument #2 ($exponent) must be greater than 0
+gmp_powm_sec(): Argument #2 ($exponent) must be greater than 0
+gmp_powm_sec(): Argument #3 ($modulus) Modulo by zero
+gmp_powm_sec(): Argument #3 ($modulus) must be odd
+Done