+/*
+ * These preprocessor symbols control various aspects of the bignum headers
+ * and library code. They're not defined by any "normal" configuration, as
+ * they are intended for development and testing purposes. NB: defining all
+ * three can be useful for debugging application code as well as openssl
+ * itself. BN_DEBUG - turn on various debugging alterations to the bignum
+ * code BN_DEBUG_RAND - uses random poisoning of unused words to trip up
+ * mismanagement of bignum internals. You must also define BN_DEBUG.
+ */
+/* #define BN_DEBUG */
+/* #define BN_DEBUG_RAND */
+
+# ifndef OPENSSL_SMALL_FOOTPRINT
+# define BN_MUL_COMBA
+# define BN_SQR_COMBA
+# define BN_RECURSION
+# endif
+
+/*
+ * This next option uses the C libraries (2 word)/(1 word) function. If it is
+ * not defined, I use my C version (which is slower). The reason for this
+ * flag is that when the particular C compiler library routine is used, and
+ * the library is linked with a different compiler, the library is missing.
+ * This mostly happens when the library is built with gcc and then linked
+ * using normal cc. This would be a common occurrence because gcc normally
+ * produces code that is 2 times faster than system compilers for the big
+ * number stuff. For machines with only one compiler (or shared libraries),
+ * this should be on. Again this in only really a problem on machines using
+ * "long long's", are 32bit, and are not using my assembler code.
+ */
+# if defined(OPENSSL_SYS_MSDOS) || defined(OPENSSL_SYS_WINDOWS) || \
+ defined(OPENSSL_SYS_WIN32) || defined(linux)
+# define BN_DIV2W
+# endif
+
+/*
+ * 64-bit processor with LP64 ABI
+ */
+# ifdef SIXTY_FOUR_BIT_LONG
+# define BN_ULLONG unsigned long long
+# define BN_BITS4 32
+# define BN_MASK2 (0xffffffffffffffffL)
+# define BN_MASK2l (0xffffffffL)
+# define BN_MASK2h (0xffffffff00000000L)
+# define BN_MASK2h1 (0xffffffff80000000L)
+# define BN_DEC_CONV (10000000000000000000UL)
+# define BN_DEC_NUM 19
+# define BN_DEC_FMT1 "%lu"
+# define BN_DEC_FMT2 "%019lu"
+# endif
+
+/*
+ * 64-bit processor other than LP64 ABI
+ */
+# ifdef SIXTY_FOUR_BIT
+# undef BN_LLONG
+# undef BN_ULLONG
+# define BN_BITS4 32
+# define BN_MASK2 (0xffffffffffffffffLL)
+# define BN_MASK2l (0xffffffffL)
+# define BN_MASK2h (0xffffffff00000000LL)
+# define BN_MASK2h1 (0xffffffff80000000LL)
+# define BN_DEC_CONV (10000000000000000000ULL)
+# define BN_DEC_NUM 19
+# define BN_DEC_FMT1 "%llu"
+# define BN_DEC_FMT2 "%019llu"
+# endif
+
+# ifdef THIRTY_TWO_BIT
+# ifdef BN_LLONG
+# if defined(_WIN32) && !defined(__GNUC__)
+# define BN_ULLONG unsigned __int64
+# else
+# define BN_ULLONG unsigned long long
+# endif
+# endif
+# define BN_BITS4 16
+# define BN_MASK2 (0xffffffffL)
+# define BN_MASK2l (0xffff)
+# define BN_MASK2h1 (0xffff8000L)
+# define BN_MASK2h (0xffff0000L)
+# define BN_DEC_CONV (1000000000L)
+# define BN_DEC_NUM 9
+# define BN_DEC_FMT1 "%u"
+# define BN_DEC_FMT2 "%09u"
+# endif
+
+
+/*-
+ * Bignum consistency macros
+ * There is one "API" macro, bn_fix_top(), for stripping leading zeroes from
+ * bignum data after direct manipulations on the data. There is also an
+ * "internal" macro, bn_check_top(), for verifying that there are no leading
+ * zeroes. Unfortunately, some auditing is required due to the fact that
+ * bn_fix_top() has become an overabused duct-tape because bignum data is
+ * occasionally passed around in an inconsistent state. So the following
+ * changes have been made to sort this out;
+ * - bn_fix_top()s implementation has been moved to bn_correct_top()
+ * - if BN_DEBUG isn't defined, bn_fix_top() maps to bn_correct_top(), and
+ * bn_check_top() is as before.
+ * - if BN_DEBUG *is* defined;
+ * - bn_check_top() tries to pollute unused words even if the bignum 'top' is
+ * consistent. (ed: only if BN_DEBUG_RAND is defined)
+ * - bn_fix_top() maps to bn_check_top() rather than "fixing" anything.
+ * The idea is to have debug builds flag up inconsistent bignums when they
+ * occur. If that occurs in a bn_fix_top(), we examine the code in question; if
+ * the use of bn_fix_top() was appropriate (ie. it follows directly after code
+ * that manipulates the bignum) it is converted to bn_correct_top(), and if it
+ * was not appropriate, we convert it permanently to bn_check_top() and track
+ * down the cause of the bug. Eventually, no internal code should be using the
+ * bn_fix_top() macro. External applications and libraries should try this with
+ * their own code too, both in terms of building against the openssl headers
+ * with BN_DEBUG defined *and* linking with a version of OpenSSL built with it
+ * defined. This not only improves external code, it provides more test
+ * coverage for openssl's own code.
+ */
+
+# ifdef BN_DEBUG
+
+# ifdef BN_DEBUG_RAND
+# define bn_pollute(a) \
+ do { \
+ const BIGNUM *_bnum1 = (a); \
+ if (_bnum1->top < _bnum1->dmax) { \
+ unsigned char _tmp_char; \
+ /* We cast away const without the compiler knowing, any \
+ * *genuinely* constant variables that aren't mutable \
+ * wouldn't be constructed with top!=dmax. */ \
+ BN_ULONG *_not_const; \
+ memcpy(&_not_const, &_bnum1->d, sizeof(_not_const)); \
+ RAND_bytes(&_tmp_char, 1); /* Debug only - safe to ignore error return */\
+ memset(_not_const + _bnum1->top, _tmp_char, \
+ sizeof(*_not_const) * (_bnum1->dmax - _bnum1->top)); \
+ } \
+ } while(0)
+# else
+# define bn_pollute(a)
+# endif
+# define bn_check_top(a) \
+ do { \
+ const BIGNUM *_bnum2 = (a); \
+ if (_bnum2 != NULL) { \
+ OPENSSL_assert(((_bnum2->top == 0) && !_bnum2->neg) || \
+ (_bnum2->top && (_bnum2->d[_bnum2->top - 1] != 0))); \
+ bn_pollute(_bnum2); \
+ } \
+ } while(0)
+
+# define bn_fix_top(a) bn_check_top(a)
+
+# define bn_check_size(bn, bits) bn_wcheck_size(bn, ((bits+BN_BITS2-1))/BN_BITS2)
+# define bn_wcheck_size(bn, words) \
+ do { \
+ const BIGNUM *_bnum2 = (bn); \
+ OPENSSL_assert((words) <= (_bnum2)->dmax && \
+ (words) >= (_bnum2)->top); \
+ /* avoid unused variable warning with NDEBUG */ \
+ (void)(_bnum2); \
+ } while(0)
+
+# else /* !BN_DEBUG */
+
+# define bn_pollute(a)
+# define bn_check_top(a)
+# define bn_fix_top(a) bn_correct_top(a)
+# define bn_check_size(bn, bits)
+# define bn_wcheck_size(bn, words)
+
+# endif
+
+BN_ULONG bn_mul_add_words(BN_ULONG *rp, const BN_ULONG *ap, int num,
+ BN_ULONG w);
+BN_ULONG bn_mul_words(BN_ULONG *rp, const BN_ULONG *ap, int num, BN_ULONG w);
+void bn_sqr_words(BN_ULONG *rp, const BN_ULONG *ap, int num);
+BN_ULONG bn_div_words(BN_ULONG h, BN_ULONG l, BN_ULONG d);
+BN_ULONG bn_add_words(BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,
+ int num);
+BN_ULONG bn_sub_words(BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,
+ int num);
+
+struct bignum_st {
+ BN_ULONG *d; /* Pointer to an array of 'BN_BITS2' bit
+ * chunks. */
+ int top; /* Index of last used d +1. */
+ /* The next are internal book keeping for bn_expand. */
+ int dmax; /* Size of the d array. */
+ int neg; /* one if the number is negative */
+ int flags;
+};
+
+/* Used for montgomery multiplication */
+struct bn_mont_ctx_st {
+ int ri; /* number of bits in R */
+ BIGNUM RR; /* used to convert to montgomery form */
+ BIGNUM N; /* The modulus */
+ BIGNUM Ni; /* R*(1/R mod N) - N*Ni = 1 (Ni is only
+ * stored for bignum algorithm) */
+ BN_ULONG n0[2]; /* least significant word(s) of Ni; (type
+ * changed with 0.9.9, was "BN_ULONG n0;"
+ * before) */
+ int flags;
+};
+
+/*
+ * Used for reciprocal division/mod functions It cannot be shared between
+ * threads
+ */
+struct bn_recp_ctx_st {
+ BIGNUM N; /* the divisor */
+ BIGNUM Nr; /* the reciprocal */
+ int num_bits;
+ int shift;
+ int flags;
+};
+
+/* Used for slow "generation" functions. */
+struct bn_gencb_st {
+ unsigned int ver; /* To handle binary (in)compatibility */
+ void *arg; /* callback-specific data */
+ union {
+ /* if (ver==1) - handles old style callbacks */
+ void (*cb_1) (int, int, void *);
+ /* if (ver==2) - new callback style */
+ int (*cb_2) (int, int, BN_GENCB *);
+ } cb;
+};
+
+/*-
+ * BN_window_bits_for_exponent_size -- macro for sliding window mod_exp functions
+ *
+ *
+ * For window size 'w' (w >= 2) and a random 'b' bits exponent,
+ * the number of multiplications is a constant plus on average
+ *
+ * 2^(w-1) + (b-w)/(w+1);
+ *
+ * here 2^(w-1) is for precomputing the table (we actually need
+ * entries only for windows that have the lowest bit set), and
+ * (b-w)/(w+1) is an approximation for the expected number of
+ * w-bit windows, not counting the first one.
+ *
+ * Thus we should use
+ *
+ * w >= 6 if b > 671
+ * w = 5 if 671 > b > 239
+ * w = 4 if 239 > b > 79
+ * w = 3 if 79 > b > 23
+ * w <= 2 if 23 > b
+ *
+ * (with draws in between). Very small exponents are often selected
+ * with low Hamming weight, so we use w = 1 for b <= 23.
+ */
+# define BN_window_bits_for_exponent_size(b) \
+ ((b) > 671 ? 6 : \
+ (b) > 239 ? 5 : \
+ (b) > 79 ? 4 : \
+ (b) > 23 ? 3 : 1)
+
+/*
+ * BN_mod_exp_mont_conttime is based on the assumption that the L1 data cache
+ * line width of the target processor is at least the following value.