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Document that BN_mod_sqrt assumes p is a prime.

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Change-Id: I5be2337ce6c333b704894c64e7931919bc047995
Reviewed-on: https://boringssl-review.googlesource.com/8595
Reviewed-by: David Benjamin <davidben@google.com>
This commit is contained in:
David Benjamin 2016-07-03 12:03:54 -04:00
parent 4cb00ba08c
commit ce9a2166d6
2 changed files with 6 additions and 6 deletions
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9
crypto/bn/sqrt.c
View File

@ -57,12 +57,11 @@
#include <openssl/err.h>
/* Returns 'ret' such that
* ret^2 == a (mod p),
* using the Tonelli/Shanks algorithm (cf. Henri Cohen, "A Course
* in Algebraic Computational Number Theory", algorithm 1.5.1).
* 'p' must be prime! */
BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx) {
/* Compute a square root of |a| mod |p| using the Tonelli/Shanks algorithm
* (cf. Henri Cohen, "A Course in Algebraic Computational Number Theory",
* algorithm 1.5.1). |p| is assumed to be a prime. */
BIGNUM *ret = in;
int err = 1;
int r;

3
include/openssl/bn.h
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@ -565,7 +565,8 @@ OPENSSL_EXPORT int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m,
OPENSSL_EXPORT int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a,
const BIGNUM *m);
/* BN_mod_sqrt returns a |BIGNUM|, r, such that r^2 == a (mod p). */
/* BN_mod_sqrt returns a |BIGNUM|, r, such that r^2 == a (mod p). |p| must be a
* prime. */
OPENSSL_EXPORT BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p,
BN_CTX *ctx);