Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / BN_add.3
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124.\" ========================================================================
125.\"
126.IX Title "BN_add 3"
e3261593 127.TH BN_add 3 "2012-01-04" "1.0.0f" "OpenSSL"
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128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
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132.SH "NAME"
133BN_add, BN_sub, BN_mul, BN_sqr, BN_div, BN_mod, BN_nnmod, BN_mod_add,
134BN_mod_sub, BN_mod_mul, BN_mod_sqr, BN_exp, BN_mod_exp, BN_gcd \-
135arithmetic operations on BIGNUMs
136.SH "SYNOPSIS"
8b0cefbb 137.IX Header "SYNOPSIS"
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138.Vb 1
139\& #include <openssl/bn.h>
e257b235 140\&
984263bc 141\& int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
e257b235 142\&
984263bc 143\& int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
e257b235 144\&
984263bc 145\& int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
e257b235 146\&
984263bc 147\& int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx);
e257b235 148\&
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149\& int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *a, const BIGNUM *d,
150\& BN_CTX *ctx);
e257b235 151\&
984263bc 152\& int BN_mod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
e257b235 153\&
984263bc 154\& int BN_nnmod(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
e257b235 155\&
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156\& int BN_mod_add(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
157\& BN_CTX *ctx);
e257b235 158\&
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159\& int BN_mod_sub(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
160\& BN_CTX *ctx);
e257b235 161\&
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162\& int BN_mod_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
163\& BN_CTX *ctx);
e257b235 164\&
984263bc 165\& int BN_mod_sqr(BIGNUM *r, BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
e257b235 166\&
984263bc 167\& int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
e257b235 168\&
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169\& int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
170\& const BIGNUM *m, BN_CTX *ctx);
e257b235 171\&
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172\& int BN_gcd(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
173.Ve
174.SH "DESCRIPTION"
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175.IX Header "DESCRIPTION"
176\&\fIBN_add()\fR adds \fIa\fR and \fIb\fR and places the result in \fIr\fR (\f(CW\*(C`r=a+b\*(C'\fR).
177\&\fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR.
984263bc 178.PP
8b0cefbb 179\&\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 180.PP
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181\&\fIBN_mul()\fR multiplies \fIa\fR and \fIb\fR and places the result in \fIr\fR (\f(CW\*(C`r=a*b\*(C'\fR).
182\&\fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR.
183For multiplication by powers of 2, use \fIBN_lshift\fR\|(3).
984263bc 184.PP
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185\&\fIBN_sqr()\fR takes the square of \fIa\fR and places the result in \fIr\fR
186(\f(CW\*(C`r=a^2\*(C'\fR). \fIr\fR and \fIa\fR may be the same \fB\s-1BIGNUM\s0\fR.
187This function is faster than BN_mul(r,a,a).
984263bc 188.PP
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189\&\fIBN_div()\fR divides \fIa\fR by \fId\fR and places the result in \fIdv\fR and the
190remainder in \fIrem\fR (\f(CW\*(C`dv=a/d, rem=a%d\*(C'\fR). Either of \fIdv\fR and \fIrem\fR may
191be \fB\s-1NULL\s0\fR, in which case the respective value is not returned.
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192The result is rounded towards zero; thus if \fIa\fR is negative, the
193remainder will be zero or negative.
194For division by powers of 2, use \fIBN_rshift\fR\|(3).
195.PP
8b0cefbb 196\&\fIBN_mod()\fR corresponds to \fIBN_div()\fR with \fIdv\fR set to \fB\s-1NULL\s0\fR.
984263bc 197.PP
8b0cefbb 198\&\fIBN_nnmod()\fR reduces \fIa\fR modulo \fIm\fR and places the non-negative
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199remainder in \fIr\fR.
200.PP
8b0cefbb 201\&\fIBN_mod_add()\fR adds \fIa\fR to \fIb\fR modulo \fIm\fR and places the non-negative
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202result in \fIr\fR.
203.PP
8b0cefbb 204\&\fIBN_mod_sub()\fR subtracts \fIb\fR from \fIa\fR modulo \fIm\fR and places the
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205non-negative result in \fIr\fR.
206.PP
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207\&\fIBN_mod_mul()\fR multiplies \fIa\fR by \fIb\fR and finds the non-negative
208remainder respective to modulus \fIm\fR (\f(CW\*(C`r=(a*b) mod m\*(C'\fR). \fIr\fR may be
209the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or \fIb\fR. For more efficient algorithms for
984263bc 210repeated computations using the same modulus, see
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211\&\fIBN_mod_mul_montgomery\fR\|(3) and
212\&\fIBN_mod_mul_reciprocal\fR\|(3).
984263bc 213.PP
8b0cefbb 214\&\fIBN_mod_sqr()\fR takes the square of \fIa\fR modulo \fBm\fR and places the
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215result in \fIr\fR.
216.PP
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217\&\fIBN_exp()\fR raises \fIa\fR to the \fIp\fR\-th power and places the result in \fIr\fR
218(\f(CW\*(C`r=a^p\*(C'\fR). This function is faster than repeated applications of
219\&\fIBN_mul()\fR.
984263bc 220.PP
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221\&\fIBN_mod_exp()\fR computes \fIa\fR to the \fIp\fR\-th power modulo \fIm\fR (\f(CW\*(C`r=a^p %
222m\*(C'\fR). This function uses less time and space than \fIBN_exp()\fR.
984263bc 223.PP
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224\&\fIBN_gcd()\fR computes the greatest common divisor of \fIa\fR and \fIb\fR and
225places the result in \fIr\fR. \fIr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fIa\fR or
226\&\fIb\fR.
984263bc 227.PP
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228For all functions, \fIctx\fR is a previously allocated \fB\s-1BN_CTX\s0\fR used for
229temporary variables; see \fIBN_CTX_new\fR\|(3).
984263bc 230.PP
8b0cefbb 231Unless noted otherwise, the result \fB\s-1BIGNUM\s0\fR must be different from
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232the arguments.
233.SH "RETURN VALUES"
8b0cefbb 234.IX Header "RETURN VALUES"
984263bc 235For all functions, 1 is returned for success, 0 on error. The return
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236value should always be checked (e.g., \f(CW\*(C`if (!BN_add(r,a,b)) goto err;\*(C'\fR).
237The error codes can be obtained by \fIERR_get_error\fR\|(3).
984263bc 238.SH "SEE ALSO"
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239.IX Header "SEE ALSO"
240\&\fIbn\fR\|(3), \fIERR_get_error\fR\|(3), \fIBN_CTX_new\fR\|(3),
241\&\fIBN_add_word\fR\|(3), \fIBN_set_bit\fR\|(3)
984263bc 242.SH "HISTORY"
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243.IX Header "HISTORY"
244\&\fIBN_add()\fR, \fIBN_sub()\fR, \fIBN_sqr()\fR, \fIBN_div()\fR, \fIBN_mod()\fR, \fIBN_mod_mul()\fR,
245\&\fIBN_mod_exp()\fR and \fIBN_gcd()\fR are available in all versions of SSLeay and
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246OpenSSL. The \fIctx\fR argument to \fIBN_mul()\fR was added in SSLeay
2470.9.1b. \fIBN_exp()\fR appeared in SSLeay 0.9.0.
8b0cefbb 248\&\fIBN_nnmod()\fR, \fIBN_mod_add()\fR, \fIBN_mod_sub()\fR, and \fIBN_mod_sqr()\fR were added in
984263bc 249OpenSSL 0.9.7.