=head1 SYNOPSIS
+ #include <openssl/bn.h>
+
BN_ULONG bn_mul_words(BN_ULONG *rp, BN_ULONG *ap, int num, BN_ULONG w);
BN_ULONG bn_mul_add_words(BN_ULONG *rp, BN_ULONG *ap, int num,
BN_ULONG w);
int nb);
void bn_mul_low_normal(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n);
void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
- BN_ULONG *tmp);
+ int dna,int dnb,BN_ULONG *tmp);
void bn_mul_part_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b,
- int tn, int n, BN_ULONG *tmp);
+ int n, int tna,int tnb, BN_ULONG *tmp);
void bn_mul_low_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b,
int n2, BN_ULONG *tmp);
void bn_mul_high(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, BN_ULONG *l,
=head2 The BIGNUM structure
- typedef struct bignum_st
+ typedef struct bignum_st BIGNUM;
+
+ struct bignum_st
{
- int top; /* index of last used d (most significant word) */
- BN_ULONG *d; /* pointer to an array of 'BITS2' bit chunks */
- int max; /* size of the d array */
- int neg; /* sign */
- } BIGNUM;
-
-The big number is stored in B<d>, a malloc()ed array of B<BN_ULONG>s,
-least significant first. A B<BN_ULONG> can be either 16, 32 or 64 bits
-in size (B<BITS2>), depending on the 'number of bits' specified in
+ 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;
+ };
+
+
+The integer value is stored in B<d>, a malloc()ed array of words (B<BN_ULONG>),
+least significant word first. A B<BN_ULONG> can be either 16, 32 or 64 bits
+in size, depending on the 'number of bits' (B<BITS2>) specified in
C<openssl/bn.h>.
-B<max> is the size of the B<d> array that has been allocated. B<top>
-is the 'last' entry being used, so for a value of 4, bn.d[0]=4 and
+B<dmax> is the size of the B<d> array that has been allocated. B<top>
+is the number of words being used, so for a value of 4, bn.d[0]=4 and
bn.top=1. B<neg> is 1 if the number is negative. When a B<BIGNUM> is
B<0>, the B<d> field can be B<NULL> and B<top> == B<0>.
+B<flags> is a bit field of flags which are defined in C<openssl/bn.h>. The
+flags begin with B<BN_FLG_>. The macros BN_set_flags(b,n) and
+BN_get_flags(b,n) exist to enable or fetch flag(s) B<n> from B<BIGNUM>
+structure B<b>.
+
Various routines in this library require the use of temporary
B<BIGNUM> variables during their execution. Since dynamic memory
allocation to create B<BIGNUM>s is rather expensive when used in
conjunction with repeated subroutine calls, the B<BN_CTX> structure is
-used. This structure contains B<BN_CTX_NUM> B<BIGNUM>s.
-B<BN_CTX_NUM> is the maximum number of temporary B<BIGNUM>s any
-publicly exported function will use.
-
- #define BN_CTX_NUM 12
- typedef struct bignum_ctx
- {
- int tos; /* top of stack */
- BIGNUM *bn[BN_CTX_NUM]; /* The variables */
- } BN_CTX;
-
-B<tos> is the index of the first unused B<BIGNUM> in the B<bn> array.
+used. This structure contains B<BN_CTX_NUM> B<BIGNUM>s, see
+L<BN_CTX_start(3)|BN_CTX_start(3)>.
=head2 Low-level arithmetic operations
array B<r>. It computes B<a>*B<b> and places the result in B<r>.
bn_mul_low_normal(B<r>, B<a>, B<b>, B<n>) operates on the B<n> word
-arrays B<r>, B<a> und B<b>. It computes the B<n> low words of
+arrays B<r>, B<a> and B<b>. It computes the B<n> low words of
B<a>*B<b> and places the result in B<r>.
-bn_mul_recursive(B<r>, B<a>, B<b>, B<n2>, B<t>) operates on the B<n2>
-word arrays B<a> and B<b> and the 2*B<n2> word arrays B<r> and B<t>.
-B<n2> must be a power of 2. It computes B<a>*B<b> and places the
-result in B<r>.
+bn_mul_recursive(B<r>, B<a>, B<b>, B<n2>, B<dna>, B<dnb>, B<t>) operates
+on the word arrays B<a> and B<b> of length B<n2>+B<dna> and B<n2>+B<dnb>
+(B<dna> and B<dnb> are currently allowed to be 0 or negative) and the 2*B<n2>
+word arrays B<r> and B<t>. B<n2> must be a power of 2. It computes
+B<a>*B<b> and places the result in B<r>.
-bn_mul_part_recursive(B<r>, B<a>, B<b>, B<tn>, B<n>, B<tmp>) operates
-on the B<n>+B<tn> word arrays B<a> and B<b> and the 4*B<n> word arrays
-B<r> and B<tmp>.
+bn_mul_part_recursive(B<r>, B<a>, B<b>, B<n>, B<tna>, B<tnb>, B<tmp>)
+operates on the word arrays B<a> and B<b> of length B<n>+B<tna> and
+B<n>+B<tnb> and the 4*B<n> word arrays B<r> and B<tmp>.
bn_mul_low_recursive(B<r>, B<a>, B<b>, B<n2>, B<tmp>) operates on the
B<n2> word arrays B<r> and B<tmp> and the B<n2>/2 word arrays B<a>
call bn_expand2(), which allocates a new B<d> array and copies the
data. They return B<NULL> on error, B<b> otherwise.
-The bn_fix_top() macro reduces B<a-E<gt>top> to most significant
-
non-zero word when B<a> has shrunk.
+The bn_fix_top() macro reduces B<a-E<gt>top> to point to the most
+
significant non-zero word plus one when B<a> has shrunk.
=head2 Debugging
-bn_check_top() verifies that C<((a)->top E<gt>= 0 && (a)-E<gt>top
-E<lt>= (a)-E<gt>max)>. A violation will cause the program to abort.
+bn_check_top() verifies that C<((a)-E<gt>top E<gt>= 0 && (a)-E<gt>top
+E<lt>= (a)-E<gt>dmax)>. A violation will cause the program to abort.
bn_print() prints B<a> to stderr. bn_dump() prints B<n> words at B<d>
(in reverse order, i.e. most significant word first) to stderr.
-bn_set_max() makes B<a> a static number with a B<max> of its current size.
+bn_set_max() makes B<a> a static number with a B<dmax> of its current size.
This is used by bn_set_low() and bn_set_high() to make B<r> a read-only
-B<BIGNUM> that contains the B<n> low
er or higher words of B<a>.
+B<BIGNUM> that contains the B<n> low
or high words of B<a>.
If B<BN_DEBUG> is not defined, bn_check_top(), bn_print(), bn_dump()
and bn_set_max() are defined as empty macros.
projects / openssl.git / blobdiff