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make RSA blinding thread-safe

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This commit is contained in:
Bodo Möller 2003-04-02 09:50:17 +00:00
parent 60511b8bb8
commit 223c80ea7d
7 changed files with 128 additions and 14 deletions
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9
CHANGES
View file

@ -14,12 +14,17 @@
to avoid a timing attack. Applications that don't want it can call
RSA_blinding_off() or use the new flag RSA_FLAG_NO_BLINDING.
They would be ill-advised to do so in most cases.
[Ben Laurie, Steve Henson, Geoff Thorpe]
[Ben Laurie, Steve Henson, Geoff Thorpe, Bodo Moeller]
*) Change RSA blinding code so that it works when the PRNG is not
seeded (in this case, the secret RSA exponent is abused as
an unpredictable seed -- if it is not unpredictable, there
is no point in blinding anyway).
is no point in blinding anyway). Make RSA blinding thread-safe
by remembering the creator's thread ID in rsa->blinding and
having all other threads use local one-time blinding factors
(this requires more computation than sharing rsa->blinding, but
avoids excessive locking; and if an RSA object is not shared
between threads, blinding will still be very fast).
[Bodo Moeller]
Changes between 0.9.6h and 0.9.6i [19 Feb 2003]

2
crypto/bn/bn.h
View file

@ -259,6 +259,8 @@ typedef struct bn_blinding_st
BIGNUM *A;
BIGNUM *Ai;
BIGNUM *mod; /* just a reference */
unsigned long thread_id; /* added in OpenSSL 0.9.6j and 0.9.7b;
* used only by crypto/rsa/rsa_eay.c, rsa_lib.c */
} BN_BLINDING;
/* Used for montgomery multiplication */

1
crypto/rsa/rsa.h
View file

@ -336,6 +336,7 @@ void ERR_load_RSA_strings(void);
#define RSA_R_DMP1_NOT_CONGRUENT_TO_D 124
#define RSA_R_DMQ1_NOT_CONGRUENT_TO_D 125
#define RSA_R_D_E_NOT_CONGRUENT_TO_1 123
#define RSA_R_INTERNAL_ERROR 133
#define RSA_R_INVALID_MESSAGE_LENGTH 131
#define RSA_R_IQMP_NOT_INVERSE_OF_Q 126
#define RSA_R_KEY_SIZE_TOO_SMALL 120

114
crypto/rsa/rsa_eay.c
View file

@ -209,6 +209,40 @@ static int rsa_eay_blinding(RSA *rsa, BN_CTX *ctx)
err_instr \
} while(0)
static BN_BLINDING *setup_blinding(RSA *rsa, BN_CTX *ctx)
{
BIGNUM *A, *Ai;
BN_BLINDING *ret = NULL;
/* added in OpenSSL 0.9.6j and 0.9.7b */
/* NB: similar code appears in RSA_blinding_on (rsa_lib.c);
* this should be placed in a new function of its own, but for reasons
* of binary compatibility can't */
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
if ((RAND_status() == 0) && rsa->d != NULL && rsa->d->d != NULL)
{
/* if PRNG is not properly seeded, resort to secret exponent as unpredictable seed */
RAND_add(rsa->d->d, rsa->d->dmax * sizeof rsa->d->d[0], 0);
if (!BN_pseudo_rand_range(A,rsa->n)) goto err;
}
else
{
if (!BN_rand_range(A,rsa->n)) goto err;
}
if ((Ai=BN_mod_inverse(NULL,A,rsa->n,ctx)) == NULL) goto err;
if (!rsa->meth->bn_mod_exp(A,A,rsa->e,rsa->n,ctx,rsa->_method_mod_n))
goto err;
ret = BN_BLINDING_new(A,Ai,rsa->n);
BN_free(Ai);
err:
BN_CTX_end(ctx);
return ret;
}
/* signing */
static int RSA_eay_private_encrypt(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
@ -217,6 +251,8 @@ static int RSA_eay_private_encrypt(int flen, unsigned char *from,
int i,j,k,num=0,r= -1;
unsigned char *buf=NULL;
BN_CTX *ctx=NULL;
int local_blinding = 0;
BN_BLINDING *blinding = NULL;
BN_init(&f);
BN_init(&ret);
@ -254,9 +290,38 @@ static int RSA_eay_private_encrypt(int flen, unsigned char *from,
}
BLINDING_HELPER(rsa, ctx, goto err;);
blinding = rsa->blinding;
/* Now unless blinding is disabled, 'blinding' is non-NULL.
* But the BN_BLINDING object may be owned by some other thread
* (we don't want to keep it constant and we don't want to use
* lots of locking to avoid race conditions, so only a single
* thread can use it; other threads have to use local blinding
* factors) */
if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_convert(&f,rsa->blinding,ctx)) goto err;
{
if (blinding == NULL)
{
RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, RSA_R_INTERNAL_ERROR);
goto err;
}
}
if (blinding != NULL)
{
if (blinding->thread_id != CRYPTO_thread_id())
{
/* we need a local one-time blinding factor */
blinding = setup_blinding(rsa, ctx);
if (blinding == NULL)
goto err;
local_blinding = 1;
}
}
if (blinding)
if (!BN_BLINDING_convert(&f, blinding, ctx)) goto err;
if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
((rsa->p != NULL) &&
@ -270,8 +335,8 @@ static int RSA_eay_private_encrypt(int flen, unsigned char *from,
if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->d,rsa->n,ctx,NULL)) goto err;
}
if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_invert(&ret,rsa->blinding,ctx)) goto err;
if (blinding)
if (!BN_BLINDING_invert(&ret, blinding, ctx)) goto err;
/* put in leading 0 bytes if the number is less than the
* length of the modulus */
@ -285,6 +350,8 @@ err:
if (ctx != NULL) BN_CTX_free(ctx);
BN_clear_free(&ret);
BN_clear_free(&f);
if (local_blinding)
BN_BLINDING_free(blinding);
if (buf != NULL)
{
OPENSSL_cleanse(buf,num);
@ -301,6 +368,8 @@ static int RSA_eay_private_decrypt(int flen, unsigned char *from,
unsigned char *p;
unsigned char *buf=NULL;
BN_CTX *ctx=NULL;
int local_blinding = 0;
BN_BLINDING *blinding = NULL;
BN_init(&f);
BN_init(&ret);
@ -333,9 +402,38 @@ static int RSA_eay_private_decrypt(int flen, unsigned char *from,
}
BLINDING_HELPER(rsa, ctx, goto err;);
blinding = rsa->blinding;
/* Now unless blinding is disabled, 'blinding' is non-NULL.
* But the BN_BLINDING object may be owned by some other thread
* (we don't want to keep it constant and we don't want to use
* lots of locking to avoid race conditions, so only a single
* thread can use it; other threads have to use local blinding
* factors) */
if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_convert(&f,rsa->blinding,ctx)) goto err;
{
if (blinding == NULL)
{
RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, RSA_R_INTERNAL_ERROR);
goto err;
}
}
if (blinding != NULL)
{
if (blinding->thread_id != CRYPTO_thread_id())
{
/* we need a local one-time blinding factor */
blinding = setup_blinding(rsa, ctx);
if (blinding == NULL)
goto err;
local_blinding = 1;
}
}
if (blinding)
if (!BN_BLINDING_convert(&f, blinding, ctx)) goto err;
/* do the decrypt */
if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
@ -351,8 +449,8 @@ static int RSA_eay_private_decrypt(int flen, unsigned char *from,
goto err;
}
if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_invert(&ret,rsa->blinding,ctx)) goto err;
if (blinding)
if (!BN_BLINDING_invert(&ret, blinding, ctx)) goto err;
p=buf;
j=BN_bn2bin(&ret,p); /* j is only used with no-padding mode */

3
crypto/rsa/rsa_err.c
View file

@ -1,6 +1,6 @@
/* crypto/rsa/rsa_err.c */
/* ====================================================================
* Copyright (c) 1999 The OpenSSL Project. All rights reserved.
* Copyright (c) 1999-2003 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -113,6 +113,7 @@ static ERR_STRING_DATA RSA_str_reasons[]=
{RSA_R_DMP1_NOT_CONGRUENT_TO_D ,"dmp1 not congruent to d"},
{RSA_R_DMQ1_NOT_CONGRUENT_TO_D ,"dmq1 not congruent to d"},
{RSA_R_D_E_NOT_CONGRUENT_TO_1 ,"d e not congruent to 1"},
{RSA_R_INTERNAL_ERROR ,"internal error"},
{RSA_R_INVALID_MESSAGE_LENGTH ,"invalid message length"},
{RSA_R_IQMP_NOT_INVERSE_OF_Q ,"iqmp not inverse of q"},
{RSA_R_KEY_SIZE_TOO_SMALL ,"key size too small"},

11
crypto/rsa/rsa_lib.c
View file

@ -273,6 +273,10 @@ int RSA_blinding_on(RSA *rsa, BN_CTX *p_ctx)
if (rsa->blinding != NULL)
BN_BLINDING_free(rsa->blinding);
/* NB: similar code appears in setup_blinding (rsa_eay.c);
* this should be placed in a new function of its own, but for reasons
* of binary compatibility can't */
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
if ((RAND_status() == 0) && rsa->d != NULL && rsa->d->d != NULL)
@ -288,8 +292,11 @@ int RSA_blinding_on(RSA *rsa, BN_CTX *p_ctx)
if ((Ai=BN_mod_inverse(NULL,A,rsa->n,ctx)) == NULL) goto err;
if (!rsa->meth->bn_mod_exp(A,A,rsa->e,rsa->n,ctx,rsa->_method_mod_n))
goto err;
rsa->blinding=BN_BLINDING_new(A,Ai,rsa->n);
goto err;
if ((rsa->blinding=BN_BLINDING_new(A,Ai,rsa->n)) == NULL) goto err;
/* to make things thread-safe without excessive locking,
* rsa->blinding will be used just by the current thread: */
rsa->blinding->thread_id = CRYPTO_thread_id();
rsa->flags |= RSA_FLAG_BLINDING;
rsa->flags &= ~RSA_FLAG_NO_BLINDING;
BN_free(Ai);

2
util/mkerr.pl
View file

@ -320,7 +320,7 @@ EOF
print OUT <<"EOF";
/* $cfile */
/* ====================================================================
* Copyright (c) 1999-2002 The OpenSSL Project. All rights reserved.
* Copyright (c) 1999-2003 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions