Timing safe str_compare() using SipHash

Author: Yasuo Ohgaki

ext/standard/basic_functions.c

@@ -2496,6 +2496,11 @@ ZEND_BEGIN_ARG_INFO_EX(arginfo_substr_compare, 0, 0, 3)
 	ZEND_ARG_INFO(0, length)
 	ZEND_ARG_INFO(0, case_sensitivity)
 ZEND_END_ARG_INFO()
+
+ZEND_BEGIN_ARG_INFO_EX(arginfo_str_compare, 0, 0, 2)
+	ZEND_ARG_INFO(0, str1)
+	ZEND_ARG_INFO(0, str2)
+ZEND_END_ARG_INFO()
 /* }}} */
 /* {{{ syslog.c */
 #ifdef HAVE_SYSLOG_H
@@ -2773,6 +2778,7 @@ const zend_function_entry basic_functions[] = { /* {{{ */
 	PHP_FE(str_split,														arginfo_str_split)
 	PHP_FE(strpbrk,															arginfo_strpbrk)
 	PHP_FE(substr_compare,													arginfo_substr_compare)
+	PHP_FE(str_compare,														arginfo_str_compare)
 
 #ifdef HAVE_STRCOLL
 	PHP_FE(strcoll,															arginfo_strcoll)

ext/standard/php_string.h

@@ -93,6 +93,7 @@ PHP_FUNCTION(str_word_count);
 PHP_FUNCTION(str_split);
 PHP_FUNCTION(strpbrk);
 PHP_FUNCTION(substr_compare);
+PHP_FUNCTION(str_compare);
 #ifdef HAVE_STRCOLL
 PHP_FUNCTION(strcoll);
 #endif
@@ -147,6 +148,8 @@ PHPAPI int string_natural_compare_function_ex(zval *result, zval *op1, zval *op2
 PHPAPI int string_natural_compare_function(zval *result, zval *op1, zval *op2 TSRMLS_DC);
 PHPAPI int string_natural_case_compare_function(zval *result, zval *op1, zval *op2 TSRMLS_DC);
 
+PHPAPI int php_byte_compare(const void *b1, const void *b2, size_t n);
+
 #ifndef HAVE_STRERROR
 PHPAPI char *php_strerror(int errnum);
 #define strerror php_strerror

ext/standard/string.c

@@ -5616,6 +5616,164 @@ PHP_FUNCTION(substr_compare)
 }
 /* }}} */
 
+
+/* XXX: Just embed here for the time being 
+ https://github.com/majek/csiphash/blob/master/csiphash.c
+*/
+/* <MIT License>
+ Copyright (c) 2013  Marek Majkowski <[email protected]>
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ THE SOFTWARE.
+ </MIT License>
+
+ Original location:
+    https://github.com/majek/csiphash/
+
+ Solution inspired by code from:
+    Samuel Neves (supercop/crypto_auth/siphash24/little)
+    djb (supercop/crypto_auth/siphash24/little2)
+    Jean-Philippe Aumasson (https://131002.net/siphash/siphash24.c)
+*/
+
+/* #include <stdint.h> */
+
+#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
+	__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#  define _le64toh(x) ((uint64_t)(x))
+#elif defined(_WIN32)
+/* Windows is always little endian, unless you're on xbox360
+   http://msdn.microsoft.com/en-us/library/b0084kay(v=vs.80).aspx */
+#  define _le64toh(x) ((uint64_t)(x))
+#elif defined(__APPLE__)
+#  include <libkern/OSByteOrder.h>
+#  define _le64toh(x) OSSwapLittleToHostInt64(x)
+#else
+
+/* See: http://sourceforge.net/p/predef/wiki/Endianness/ */
+#  if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__)
+#    include <sys/endian.h>
+#  else
+#    include <endian.h>
+#  endif
+#  if defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && \
+	__BYTE_ORDER == __LITTLE_ENDIAN
+#    define _le64toh(x) ((uint64_t)(x))
+#  else
+#    define _le64toh(x) le64toh(x)
+#  endif
+
+#endif
+
+
+#define ROTATE(x, b) (uint64_t)( ((x) << (b)) | ( (x) >> (64 - (b))) )
+
+#define HALF_ROUND(a,b,c,d,s,t)			\
+	a += b; c += d;				\
+	b = ROTATE(b, s) ^ a;			\
+	d = ROTATE(d, t) ^ c;			\
+	a = ROTATE(a, 32);
+
+#define DOUBLE_ROUND(v0,v1,v2,v3)		\
+	HALF_ROUND(v0,v1,v2,v3,13,16);		\
+	HALF_ROUND(v2,v1,v0,v3,17,21);		\
+	HALF_ROUND(v0,v1,v2,v3,13,16);		\
+	HALF_ROUND(v2,v1,v0,v3,17,21);
+
+
+static uint64_t php_siphash(const void *src, unsigned long src_sz, const char key[16]) {
+	const uint64_t *_key = (uint64_t *)key;
+	uint64_t k0 = _le64toh(_key[0]);
+	uint64_t k1 = _le64toh(_key[1]);
+	uint64_t b = (uint64_t)src_sz << 56;
+	const uint64_t *in = (uint64_t*)src;
+
+	uint64_t v0 = k0 ^ 0x736f6d6570736575ULL;
+	uint64_t v1 = k1 ^ 0x646f72616e646f6dULL;
+	uint64_t v2 = k0 ^ 0x6c7967656e657261ULL;
+	uint64_t v3 = k1 ^ 0x7465646279746573ULL;
+
+	while (src_sz >= 8) {
+		uint64_t mi = _le64toh(*in);
+		in += 1; src_sz -= 8;
+		v3 ^= mi;
+		DOUBLE_ROUND(v0,v1,v2,v3);
+		v0 ^= mi;
+	}
+
+	uint64_t t = 0; uint8_t *pt = (uint8_t *)&t; uint8_t *m = (uint8_t *)in;
+	switch (src_sz) {
+	case 7: pt[6] = m[6];
+	case 6: pt[5] = m[5];
+	case 5: pt[4] = m[4];
+	case 4: *((uint32_t*)&pt[0]) = *((uint32_t*)&m[0]); break;
+	case 3: pt[2] = m[2];
+	case 2: pt[1] = m[1];
+	case 1: pt[0] = m[0];
+	}
+	b |= _le64toh(t);
+
+	v3 ^= b;
+	DOUBLE_ROUND(v0,v1,v2,v3);
+	v0 ^= b; v2 ^= 0xff;
+	DOUBLE_ROUND(v0,v1,v2,v3);
+	DOUBLE_ROUND(v0,v1,v2,v3);
+	return (v0 ^ v1) ^ (v2 ^ v3);
+}
+/* END SipHash */
+
+/* Timing safe compare */
+PHPAPI int php_compare(const void *b1, const void *b2, size_t n) /* {{{ */
+{
+	const unsigned char *p1 = b1, *p2 = b2;
+	int ret = 0;
+
+	for (; n > 0; n--) {
+		ret |= *p1++ ^ *p2++;
+	}
+	return (ret != 0);
+}
+/* }}} */
+
+/* {{{ proto bool str_compare(string str1, string str2)
+   Timing safe string compare */
+PHP_FUNCTION(str_compare)
+{
+	zval *s1, *s2;
+	char key[16] = {0,1,2,3,4,5,6,7,8,9,0xa,0xb,0xc,0xd,0xe,0xf};
+
+	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "zz", &s1, &s2) == FAILURE) {
+		RETURN_FALSE;
+	}
+
+	if (Z_TYPE_P(s1) != IS_STRING || Z_TYPE_P(s2) != IS_STRING) {
+		php_error_docref(NULL TSRMLS_CC, E_WARNING, "Paremeters must be string");
+		RETURN_FALSE;
+	}
+	if (Z_STRLEN_P(s1) != Z_STRLEN_P(s2)) {
+		RETURN_FALSE;
+	}
+	
+
+	RETURN_BOOL(php_siphash(Z_STRVAL_P(s1), Z_STRLEN_P(s1), key) == php_siphash(Z_STRVAL_P(s2), Z_STRLEN_P(s2), key));
+}
+/* }}} */
+
 /*
  * Local variables:
  * tab-width: 4