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SUSE:SLE-12-SP5:GA
openssl.14115
openssl-bn_mul_mont_fixed_top.patch
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File openssl-bn_mul_mont_fixed_top.patch of Package openssl.14115
From 71883868ea5b33416ae8283bcc38dd2d97e5006b Mon Sep 17 00:00:00 2001 From: Andy Polyakov <appro@openssl.org> Date: Fri, 6 Jul 2018 15:13:15 +0200 Subject: [PATCH] bn/bn_{mont|exp}.c: switch to zero-padded intermediate vectors. Note that exported functions maintain original behaviour, so that external callers won't observe difference. While internally we can now perform Montogomery multiplication on fixed-length vectors, fixed at modulus size. The new functions, bn_to_mont_fixed_top and bn_mul_mont_fixed_top, are declared in bn_int.h, because one can use them even outside bn, e.g. in RSA, DSA, ECDSA... Reviewed-by: Rich Salz <rsalz@openssl.org> Reviewed-by: David Benjamin <davidben@google.com> (Merged from https://github.com/openssl/openssl/pull/6662) --- crypto/bn/bn_exp.c | 47 ++++++++++++++++++-------------- crypto/bn/bn_lcl.h | 3 +- crypto/bn/bn_mont.c | 45 ++++++++++++++++++++++-------- crypto/bn_int.h | 12 ++++++++ 4 files changed, 74 insertions(+), 33 deletions(-) Index: openssl-1.0.1i/crypto/bn/bn_exp.c =================================================================== --- openssl-1.0.1i.orig/crypto/bn/bn_exp.c +++ openssl-1.0.1i/crypto/bn/bn_exp.c @@ -445,18 +445,19 @@ int BN_mod_exp_mont(BIGNUM *rr, const BI ret = 1; goto err; } - if (!BN_to_montgomery(val[0],aa,mont,ctx)) goto err; /* 1 */ + if (!bn_to_mont_fixed_top(val[0], aa, mont, ctx)) + goto err; /* 1 */ window = BN_window_bits_for_exponent_size(bits); if (window > 1) { - if (!BN_mod_mul_montgomery(d,val[0],val[0],mont,ctx)) goto err; /* 2 */ + if (!bn_mul_mont_fixed_top(d, val[0], val[0], mont, ctx)) + goto err; /* 2 */ j=1<<(window-1); for (i=1; i<j; i++) { if(((val[i] = BN_CTX_get(ctx)) == NULL) || - !BN_mod_mul_montgomery(val[i],val[i-1], - d,mont,ctx)) + !bn_mul_mont_fixed_top(val[i], val[i - 1], d, mont, ctx)) goto err; } } @@ -468,14 +469,15 @@ int BN_mod_exp_mont(BIGNUM *rr, const BI wstart=bits-1; /* The top bit of the window */ wend=0; /* The bottom bit of the window */ - if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err; + if (!bn_to_mont_fixed_top(r, BN_value_one(), mont, ctx)) + goto err; for (;;) { if (BN_is_bit_set(p,wstart) == 0) { if (!start) { - if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) + if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx)) goto err; } if (wstart == 0) break; @@ -506,12 +508,12 @@ int BN_mod_exp_mont(BIGNUM *rr, const BI if (!start) for (i=0; i<j; i++) { - if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) + if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx)) goto err; } /* wvalue will be an odd number < 2^window */ - if (!BN_mod_mul_montgomery(r,r,val[wvalue>>1],mont,ctx)) + if (!bn_mul_mont_fixed_top(r, r, val[wvalue >> 1], mont, ctx)) goto err; /* move the 'window' down further */ @@ -617,7 +619,7 @@ static int MOD_EXP_CTIME_COPY_FROM_PREBU } b->top = top; - bn_correct_top(b); + b->flags |= BN_FLG_FIXED_TOP; return 1; } @@ -713,7 +715,8 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr /* prepare a^0 in Montgomery domain */ #if 1 - if (!BN_to_montgomery(&tmp,BN_value_one(),mont,ctx)) goto err; + if (!bn_to_mont_fixed_top(&tmp, BN_value_one(), mont, ctx)) + goto err; #else tmp.d[0] = (0-m->d[0])&BN_MASK2; /* 2^(top*BN_BITS2) - m */ for (i=1;i<top;i++) @@ -725,9 +728,9 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr if (a->neg || BN_ucmp(a,m) >= 0) { if (!BN_mod(&am,a,m,ctx)) goto err; - if (!BN_to_montgomery(&am,&am,mont,ctx)) goto err; + if (!bn_to_mont_fixed_top(&am, &am, mont, ctx)) goto err; } - else if (!BN_to_montgomery(&am,a,mont,ctx)) goto err; + else if (!bn_to_mont_fixed_top(&am,a,mont,ctx)) goto err; #if defined(OPENSSL_BN_ASM_MONT5) /* This optimization uses ideas from http://eprint.iacr.org/2011/239, @@ -833,13 +836,13 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr */ if (window > 1) { - if (!BN_mod_mul_montgomery(&tmp,&am,&am,mont,ctx)) goto err; + if (!bn_mul_mont_fixed_top(&tmp,&am,&am,mont,ctx)) goto err; if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2, window)) goto err; for (i=3; i<numPowers; i++) { /* Calculate a^i = a^(i-1) * a */ - if (!BN_mod_mul_montgomery(&tmp,&am,&tmp,mont,ctx)) + if (!bn_mul_mont_fixed_top(&tmp,&am,&tmp,mont,ctx)) goto err; if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i, window)) goto err; @@ -867,7 +870,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr while (bits > 0) { /* Square the result window-size times */ for (i = 0; i < window; i++) - if (!BN_mod_mul_montgomery(&tmp,&tmp,&tmp,mont,ctx)) goto err; + if (!bn_mul_mont_fixed_top(&tmp,&tmp,&tmp,mont,ctx)) goto err; /* * Get a window's worth of bits from the exponent @@ -886,11 +889,15 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr window)) goto err; /* Multiply the result into the intermediate result */ - if (!BN_mod_mul_montgomery(&tmp,&tmp,&am,mont,ctx)) goto err; + if (!bn_mul_mont_fixed_top(&tmp,&tmp,&am,mont,ctx)) goto err; } } - /* Convert the final result from montgomery to standard format */ + /* + * Done with zero-padded intermediate BIGNUMs. Final BN_from_montgomery + * removes padding [if any] and makes return value suitable for public + * API consumer. + */ if (!BN_from_montgomery(rr,&tmp,mont,ctx)) goto err; ret=1; err: Index: openssl-1.0.1i/crypto/bn/bn_mont.c =================================================================== --- openssl-1.0.1i.orig/crypto/bn/bn_mont.c +++ openssl-1.0.1i/crypto/bn/bn_mont.c @@ -123,12 +123,21 @@ #define MONT_WORD /* use the faster word-based algorithm */ #ifdef MONT_WORD -static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont); +static int bn_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont); #endif int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_MONT_CTX *mont, BN_CTX *ctx) { + int ret = bn_mul_mont_fixed_top(r, a, b, mont, ctx); + bn_correct_top(r); + bn_check_top(r); + return ret; + } + +int bn_mul_mont_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + BN_MONT_CTX *mont, BN_CTX *ctx) +{ BIGNUM *tmp; int ret=0; #if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD) @@ -141,7 +150,7 @@ int BN_mod_mul_montgomery(BIGNUM *r, con { r->neg = a->neg^b->neg; r->top = num; - bn_correct_top(r); + r->flags |= BN_FLG_FIXED_TOP; return(1); } } @@ -161,11 +170,10 @@ int BN_mod_mul_montgomery(BIGNUM *r, con } /* reduce from aRR to aR */ #ifdef MONT_WORD - if (!BN_from_montgomery_word(r,tmp,mont)) goto err; + if (!bn_from_montgomery_word(r,tmp,mont)) goto err; #else if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err; #endif - bn_check_top(r); ret=1; err: BN_CTX_end(ctx); @@ -173,7 +181,7 @@ err: } #ifdef MONT_WORD -static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) +static int bn_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) { BIGNUM *n; BN_ULONG *ap,*np,*rp,n0,v,carry; @@ -198,6 +206,7 @@ static int BN_from_montgomery_word(BIGNU } r->top=max; + r->flags |= BN_FLG_FIXED_TOP; n0=mont->n0[0]; #ifdef BN_COUNT @@ -229,6 +238,7 @@ static int BN_from_montgomery_word(BIGNU if (bn_wexpand(ret,nl) == NULL) return(0); ret->top=nl; + ret->flags |= BN_FLG_FIXED_TOP; ret->neg=r->neg; rp=ret->d; @@ -294,8 +304,11 @@ int bn_from_mont_fixed_top(BIGNUM *ret, BIGNUM *t; BN_CTX_start(ctx); - if ((t = BN_CTX_get(ctx)) && BN_copy(t,a)) - retn = BN_from_montgomery_word(ret,t,mont); + if ((t = BN_CTX_get(ctx)) && BN_copy(t, a)) { + retn = bn_from_montgomery_word(ret, t, mont); + bn_correct_top(ret); + bn_check_top(ret); + } BN_CTX_end(ctx); #else /* !MONT_WORD */ BIGNUM *t1,*t2; @@ -327,6 +340,12 @@ int bn_from_mont_fixed_top(BIGNUM *ret, return(retn); } +int bn_to_mont_fixed_top(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont, + BN_CTX *ctx) +{ + return bn_mul_mont_fixed_top(r, a, &(mont->RR), mont, ctx); +} + BN_MONT_CTX *BN_MONT_CTX_new(void) { BN_MONT_CTX *ret; @@ -363,7 +382,7 @@ void BN_MONT_CTX_free(BN_MONT_CTX *mont) int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx) { - int ret = 0; + int i, ret = 0; BIGNUM *Ri,*R; BN_CTX_start(ctx); @@ -465,6 +484,11 @@ int BN_MONT_CTX_set(BN_MONT_CTX *mont, c if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err; if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err; + for (i = mont->RR.top, ret = mont->N.top; i < ret; i++) + mont->RR.d[i] = 0; + mont->RR.top = ret; + mont->RR.flags |= BN_FLG_FIXED_TOP; + ret = 1; err: BN_CTX_end(ctx); Index: openssl-1.0.1i/crypto/bn/bn.h =================================================================== --- openssl-1.0.1i.orig/crypto/bn/bn.h +++ openssl-1.0.1i/crypto/bn/bn.h @@ -330,7 +330,8 @@ struct bignum_st struct bn_mont_ctx_st { int ri; /* number of bits in R */ - BIGNUM RR; /* used to convert to montgomery form */ + BIGNUM RR; /* used to convert to montgomery form, + possibly zero-padded */ BIGNUM N; /* The modulus */ BIGNUM Ni; /* R*(1/R mod N) - N*Ni = 1 * (Ni is only stored for bignum algorithm) */ @@ -581,6 +582,12 @@ int BN_mod_mul_montgomery(BIGNUM *r,cons int BN_from_montgomery(BIGNUM *r,const BIGNUM *a, BN_MONT_CTX *mont, BN_CTX *ctx); int bn_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen); +int bn_mul_mont_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + BN_MONT_CTX *mont, BN_CTX *ctx); +int bn_to_mont_fixed_top(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont, + BN_CTX *ctx); +int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m); int bn_from_mont_fixed_top(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont, BN_CTX *ctx); int bn_mod_sub_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
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