diff options
Diffstat (limited to 'crypto/openssl/crypto/bn/bn_recp.c')
| -rw-r--r-- | crypto/openssl/crypto/bn/bn_recp.c | 48 |
1 files changed, 29 insertions, 19 deletions
diff --git a/crypto/openssl/crypto/bn/bn_recp.c b/crypto/openssl/crypto/bn/bn_recp.c index d019941..ef5fdd4 100644 --- a/crypto/openssl/crypto/bn/bn_recp.c +++ b/crypto/openssl/crypto/bn/bn_recp.c @@ -93,18 +93,19 @@ void BN_RECP_CTX_free(BN_RECP_CTX *recp) int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx) { - BN_copy(&(recp->N),d); - BN_zero(&(recp->Nr)); + if (!BN_copy(&(recp->N),d)) return 0; + if (!BN_zero(&(recp->Nr))) return 0; recp->num_bits=BN_num_bits(d); recp->shift=0; return(1); } -int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp, - BN_CTX *ctx) +int BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y, + BN_RECP_CTX *recp, BN_CTX *ctx) { int ret=0; BIGNUM *a; + const BIGNUM *ca; BN_CTX_start(ctx); if ((a = BN_CTX_get(ctx)) == NULL) goto err; @@ -114,19 +115,19 @@ int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp, { if (!BN_sqr(a,x,ctx)) goto err; } else { if (!BN_mul(a,x,y,ctx)) goto err; } + ca = a; } else - a=x; /* Just do the mod */ + ca=x; /* Just do the mod */ - BN_div_recp(NULL,r,a,recp,ctx); - ret=1; + ret = BN_div_recp(NULL,r,ca,recp,ctx); err: BN_CTX_end(ctx); return(ret); } -int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp, - BN_CTX *ctx) +int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, + BN_RECP_CTX *recp, BN_CTX *ctx) { int i,j,ret=0; BIGNUM *a,*b,*d,*r; @@ -146,8 +147,8 @@ int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp, if (BN_ucmp(m,&(recp->N)) < 0) { - BN_zero(d); - BN_copy(r,m); + if (!BN_zero(d)) return 0; + if (!BN_copy(r,m)) return 0; BN_CTX_end(ctx); return(1); } @@ -157,20 +158,28 @@ int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp, * we need multiply ABCDEF by 3 digests of the reciprocal of ab * */ - i=BN_num_bits(m); + /* i := max(BN_num_bits(m), 2*BN_num_bits(N)) */ + i=BN_num_bits(m); j=recp->num_bits<<1; if (j>i) i=j; - j>>=1; + /* Nr := round(2^i / N) */ if (i != recp->shift) recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N), - i,ctx); + i,ctx); /* BN_reciprocal returns i, or -1 for an error */ + if (recp->shift == -1) goto err; - if (!BN_rshift(a,m,j)) goto err; + /* d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))| + * = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))| + * <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)| + * = |m/N| + */ + if (!BN_rshift(a,m,recp->num_bits)) goto err; if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err; - if (!BN_rshift(d,b,i-j)) goto err; + if (!BN_rshift(d,b,i-recp->num_bits)) goto err; d->neg=0; + if (!BN_mul(b,&(recp->N),d,ctx)) goto err; if (!BN_usub(r,m,b)) goto err; r->neg=0; @@ -201,20 +210,21 @@ err: * We actually calculate with an extra word of precision, so * we can do faster division if the remainder is not required. */ -int BN_reciprocal(BIGNUM *r, BIGNUM *m, int len, BN_CTX *ctx) +/* r := 2^len / m */ +int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx) { int ret= -1; BIGNUM t; BN_init(&t); - BN_zero(&t); + if (!BN_zero(&t)) goto err; if (!BN_set_bit(&t,len)) goto err; if (!BN_div(r,NULL,&t,m,ctx)) goto err; + ret=len; err: BN_free(&t); return(ret); } - |
