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[dragonfly.git] / secure / lib / libcrypto / man / BN_add.3
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138.\" ======================================================================
139.\"
140.IX Title "BN_add 3"
141.TH BN_add 3 "0.9.7a" "2003-02-19" "OpenSSL"
142.UC
143.SH "NAME"
144BN_add, BN_sub, BN_mul, BN_sqr, BN_div, BN_mod, BN_nnmod, BN_mod_add,
145BN_mod_sub, BN_mod_mul, BN_mod_sqr, BN_exp, BN_mod_exp, BN_gcd \-
146arithmetic operations on BIGNUMs
147.SH "SYNOPSIS"
148.IX Header "SYNOPSIS"
149.Vb 1
150\& #include <openssl/bn.h>
151.Ve
152.Vb 1
153\& int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
154.Ve
155.Vb 1
156\& int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
157.Ve
158.Vb 1
159\& int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
160.Ve
161.Vb 1
162\& int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx);
163.Ve
164.Vb 2
165\& int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *a, const BIGNUM *d,
166\& BN_CTX *ctx);
167.Ve
168.Vb 1
169\& int BN_mod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
170.Ve
171.Vb 1
172\& int BN_nnmod(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
173.Ve
174.Vb 2
175\& int BN_mod_add(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
176\& BN_CTX *ctx);
177.Ve
178.Vb 2
179\& int BN_mod_sub(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
180\& BN_CTX *ctx);
181.Ve
182.Vb 2
183\& int BN_mod_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
184\& BN_CTX *ctx);
185.Ve
186.Vb 1
187\& int BN_mod_sqr(BIGNUM *r, BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
188.Ve
189.Vb 1
190\& int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
191.Ve
192.Vb 2
193\& int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
194\& const BIGNUM *m, BN_CTX *ctx);
195.Ve
196.Vb 1
197\& int BN_gcd(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
198.Ve
199.SH "DESCRIPTION"
200.IX Header "DESCRIPTION"
201\&\fIBN_add()\fR adds \fIa\fR and \fIb\fR and places the result in \fIr\fR (\f(CW\*(C`r=a+b\*(C'\fR).
202\&\fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR.
203.PP
204\&\fIBN_sub()\fR subtracts \fIb\fR from \fIa\fR and places the result in \fIr\fR (\f(CW\*(C`r=a\-b\*(C'\fR).
205.PP
206\&\fIBN_mul()\fR multiplies \fIa\fR and \fIb\fR and places the result in \fIr\fR (\f(CW\*(C`r=a*b\*(C'\fR).
207\&\fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR.
208For multiplication by powers of 2, use BN_lshift(3).
209.PP
210\&\fIBN_sqr()\fR takes the square of \fIa\fR and places the result in \fIr\fR
211(\f(CW\*(C`r=a^2\*(C'\fR). \fIr\fR and \fIa\fR may be the same \fB\s-1BIGNUM\s0\fR.
212This function is faster than BN_mul(r,a,a).
213.PP
214\&\fIBN_div()\fR divides \fIa\fR by \fId\fR and places the result in \fIdv\fR and the
215remainder in \fIrem\fR (\f(CW\*(C`dv=a/d, rem=a%d\*(C'\fR). Either of \fIdv\fR and \fIrem\fR may
216be \fB\s-1NULL\s0\fR, in which case the respective value is not returned.
217The result is rounded towards zero; thus if \fIa\fR is negative, the
218remainder will be zero or negative.
219For division by powers of 2, use \fIBN_rshift\fR\|(3).
220.PP
221\&\fIBN_mod()\fR corresponds to \fIBN_div()\fR with \fIdv\fR set to \fB\s-1NULL\s0\fR.
222.PP
223\&\fIBN_nnmod()\fR reduces \fIa\fR modulo \fIm\fR and places the non-negative
224remainder in \fIr\fR.
225.PP
226\&\fIBN_mod_add()\fR adds \fIa\fR to \fIb\fR modulo \fIm\fR and places the non-negative
227result in \fIr\fR.
228.PP
229\&\fIBN_mod_sub()\fR subtracts \fIb\fR from \fIa\fR modulo \fIm\fR and places the
230non-negative result in \fIr\fR.
231.PP
232\&\fIBN_mod_mul()\fR multiplies \fIa\fR by \fIb\fR and finds the non-negative
233remainder respective to modulus \fIm\fR (\f(CW\*(C`r=(a*b) mod m\*(C'\fR). \fIr\fR may be
234the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR. For more efficient algorithms for
235repeated computations using the same modulus, see
236BN_mod_mul_montgomery(3) and
237BN_mod_mul_reciprocal(3).
238.PP
239\&\fIBN_mod_sqr()\fR takes the square of \fIa\fR modulo \fBm\fR and places the
240result in \fIr\fR.
241.PP
242\&\fIBN_exp()\fR raises \fIa\fR to the \fIp\fR\-th power and places the result in \fIr\fR
243(\f(CW\*(C`r=a^p\*(C'\fR). This function is faster than repeated applications of
244\&\fIBN_mul()\fR.
245.PP
246\&\fIBN_mod_exp()\fR computes \fIa\fR to the \fIp\fR\-th power modulo \fIm\fR (\f(CW\*(C`r=a^p %
247m\*(C'\fR). This function uses less time and space than \fIBN_exp()\fR.
248.PP
249\&\fIBN_gcd()\fR computes the greatest common divisor of \fIa\fR and \fIb\fR and
250places the result in \fIr\fR. \fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or
251\&\fIb\fR.
252.PP
253For all functions, \fIctx\fR is a previously allocated \fB\s-1BN_CTX\s0\fR used for
254temporary variables; see BN_CTX_new(3).
255.PP
256Unless noted otherwise, the result \fB\s-1BIGNUM\s0\fR must be different from
257the arguments.
258.SH "RETURN VALUES"
259.IX Header "RETURN VALUES"
260For all functions, 1 is returned for success, 0 on error. The return
261value should always be checked (e.g., \f(CW\*(C`if (!BN_add(r,a,b)) goto err;\*(C'\fR).
262The error codes can be obtained by ERR_get_error(3).
263.SH "SEE ALSO"
264.IX Header "SEE ALSO"
265bn(3), ERR_get_error(3), BN_CTX_new(3),
266BN_add_word(3), BN_set_bit(3)
267.SH "HISTORY"
268.IX Header "HISTORY"
269\&\fIBN_add()\fR, \fIBN_sub()\fR, \fIBN_sqr()\fR, \fIBN_div()\fR, \fIBN_mod()\fR, \fIBN_mod_mul()\fR,
270\&\fIBN_mod_exp()\fR and \fIBN_gcd()\fR are available in all versions of SSLeay and
271OpenSSL. The \fIctx\fR argument to \fIBN_mul()\fR was added in SSLeay
2720.9.1b. \fIBN_exp()\fR appeared in SSLeay 0.9.0.
273\&\fIBN_nnmod()\fR, \fIBN_mod_add()\fR, \fIBN_mod_sub()\fR, and \fIBN_mod_sqr()\fR were added in
274OpenSSL 0.9.7.