Upgrade to OpenSSL 0.9.8h.
[dragonfly.git] / secure / lib / libcrypto / man / BN_add.3
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129.\" ========================================================================
130.\"
131.IX Title "BN_add 3"
aac4ff6f 132.TH BN_add 3 "2008-09-06" "0.9.8h" "OpenSSL"
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133.SH "NAME"
134BN_add, BN_sub, BN_mul, BN_sqr, BN_div, BN_mod, BN_nnmod, BN_mod_add,
135BN_mod_sub, BN_mod_mul, BN_mod_sqr, BN_exp, BN_mod_exp, BN_gcd \-
136arithmetic operations on BIGNUMs
137.SH "SYNOPSIS"
8b0cefbb 138.IX Header "SYNOPSIS"
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139.Vb 1
140\& #include <openssl/bn.h>
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141.Ve
142.PP
143.Vb 1
984263bc 144\& int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
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145.Ve
146.PP
147.Vb 1
984263bc 148\& int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
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149.Ve
150.PP
151.Vb 1
984263bc 152\& int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
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153.Ve
154.PP
155.Vb 1
984263bc 156\& int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx);
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157.Ve
158.PP
159.Vb 2
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160\& int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *a, const BIGNUM *d,
161\& BN_CTX *ctx);
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162.Ve
163.PP
164.Vb 1
984263bc 165\& int BN_mod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
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166.Ve
167.PP
168.Vb 1
984263bc 169\& int BN_nnmod(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
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170.Ve
171.PP
172.Vb 2
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173\& int BN_mod_add(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
174\& BN_CTX *ctx);
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175.Ve
176.PP
177.Vb 2
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178\& int BN_mod_sub(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
179\& BN_CTX *ctx);
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180.Ve
181.PP
182.Vb 2
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183\& int BN_mod_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
184\& BN_CTX *ctx);
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185.Ve
186.PP
187.Vb 1
984263bc 188\& int BN_mod_sqr(BIGNUM *r, BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
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189.Ve
190.PP
191.Vb 1
984263bc 192\& int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
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193.Ve
194.PP
195.Vb 2
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196\& int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
197\& const BIGNUM *m, BN_CTX *ctx);
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198.Ve
199.PP
200.Vb 1
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201\& int BN_gcd(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
202.Ve
203.SH "DESCRIPTION"
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204.IX Header "DESCRIPTION"
205\&\fIBN_add()\fR adds \fIa\fR and \fIb\fR and places the result in \fIr\fR (\f(CW\*(C`r=a+b\*(C'\fR).
206\&\fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR.
984263bc 207.PP
8b0cefbb 208\&\fIBN_sub()\fR subtracts \fIb\fR from \fIa\fR and places the result in \fIr\fR (\f(CW\*(C`r=a\-b\*(C'\fR).
984263bc 209.PP
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210\&\fIBN_mul()\fR multiplies \fIa\fR and \fIb\fR and places the result in \fIr\fR (\f(CW\*(C`r=a*b\*(C'\fR).
211\&\fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR.
212For multiplication by powers of 2, use \fIBN_lshift\fR\|(3).
984263bc 213.PP
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214\&\fIBN_sqr()\fR takes the square of \fIa\fR and places the result in \fIr\fR
215(\f(CW\*(C`r=a^2\*(C'\fR). \fIr\fR and \fIa\fR may be the same \fB\s-1BIGNUM\s0\fR.
216This function is faster than BN_mul(r,a,a).
984263bc 217.PP
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218\&\fIBN_div()\fR divides \fIa\fR by \fId\fR and places the result in \fIdv\fR and the
219remainder in \fIrem\fR (\f(CW\*(C`dv=a/d, rem=a%d\*(C'\fR). Either of \fIdv\fR and \fIrem\fR may
220be \fB\s-1NULL\s0\fR, in which case the respective value is not returned.
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221The result is rounded towards zero; thus if \fIa\fR is negative, the
222remainder will be zero or negative.
223For division by powers of 2, use \fIBN_rshift\fR\|(3).
224.PP
8b0cefbb 225\&\fIBN_mod()\fR corresponds to \fIBN_div()\fR with \fIdv\fR set to \fB\s-1NULL\s0\fR.
984263bc 226.PP
8b0cefbb 227\&\fIBN_nnmod()\fR reduces \fIa\fR modulo \fIm\fR and places the non-negative
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228remainder in \fIr\fR.
229.PP
8b0cefbb 230\&\fIBN_mod_add()\fR adds \fIa\fR to \fIb\fR modulo \fIm\fR and places the non-negative
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231result in \fIr\fR.
232.PP
8b0cefbb 233\&\fIBN_mod_sub()\fR subtracts \fIb\fR from \fIa\fR modulo \fIm\fR and places the
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234non-negative result in \fIr\fR.
235.PP
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236\&\fIBN_mod_mul()\fR multiplies \fIa\fR by \fIb\fR and finds the non-negative
237remainder respective to modulus \fIm\fR (\f(CW\*(C`r=(a*b) mod m\*(C'\fR). \fIr\fR may be
238the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR. For more efficient algorithms for
984263bc 239repeated computations using the same modulus, see
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240\&\fIBN_mod_mul_montgomery\fR\|(3) and
241\&\fIBN_mod_mul_reciprocal\fR\|(3).
984263bc 242.PP
8b0cefbb 243\&\fIBN_mod_sqr()\fR takes the square of \fIa\fR modulo \fBm\fR and places the
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244result in \fIr\fR.
245.PP
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246\&\fIBN_exp()\fR raises \fIa\fR to the \fIp\fR\-th power and places the result in \fIr\fR
247(\f(CW\*(C`r=a^p\*(C'\fR). This function is faster than repeated applications of
248\&\fIBN_mul()\fR.
984263bc 249.PP
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250\&\fIBN_mod_exp()\fR computes \fIa\fR to the \fIp\fR\-th power modulo \fIm\fR (\f(CW\*(C`r=a^p %
251m\*(C'\fR). This function uses less time and space than \fIBN_exp()\fR.
984263bc 252.PP
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253\&\fIBN_gcd()\fR computes the greatest common divisor of \fIa\fR and \fIb\fR and
254places the result in \fIr\fR. \fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or
255\&\fIb\fR.
984263bc 256.PP
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257For all functions, \fIctx\fR is a previously allocated \fB\s-1BN_CTX\s0\fR used for
258temporary variables; see \fIBN_CTX_new\fR\|(3).
984263bc 259.PP
8b0cefbb 260Unless noted otherwise, the result \fB\s-1BIGNUM\s0\fR must be different from
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261the arguments.
262.SH "RETURN VALUES"
8b0cefbb 263.IX Header "RETURN VALUES"
984263bc 264For all functions, 1 is returned for success, 0 on error. The return
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265value should always be checked (e.g., \f(CW\*(C`if (!BN_add(r,a,b)) goto err;\*(C'\fR).
266The error codes can be obtained by \fIERR_get_error\fR\|(3).
984263bc 267.SH "SEE ALSO"
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268.IX Header "SEE ALSO"
269\&\fIbn\fR\|(3), \fIERR_get_error\fR\|(3), \fIBN_CTX_new\fR\|(3),
270\&\fIBN_add_word\fR\|(3), \fIBN_set_bit\fR\|(3)
984263bc 271.SH "HISTORY"
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272.IX Header "HISTORY"
273\&\fIBN_add()\fR, \fIBN_sub()\fR, \fIBN_sqr()\fR, \fIBN_div()\fR, \fIBN_mod()\fR, \fIBN_mod_mul()\fR,
274\&\fIBN_mod_exp()\fR and \fIBN_gcd()\fR are available in all versions of SSLeay and
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275OpenSSL. The \fIctx\fR argument to \fIBN_mul()\fR was added in SSLeay
2760.9.1b. \fIBN_exp()\fR appeared in SSLeay 0.9.0.
8b0cefbb 277\&\fIBN_nnmod()\fR, \fIBN_mod_add()\fR, \fIBN_mod_sub()\fR, and \fIBN_mod_sqr()\fR were added in
984263bc 278OpenSSL 0.9.7.