Is this a new advisory. I've patched for a previous timing attack 2
weeks ago.
On Mon, 2003-03-17 at 03:47, Ben Laurie wrote:
> I expect a release to follow shortly.
>
> --
> http://www.apache-ssl.org/ben.html http://www.thebunker.net/
>
> "There is no limit to what a man can do or how far he can go if he
> doesn't mind who gets the credit." - Robert Woodruff
> ----
>
> OpenSSL v0.9.7a and 0.9.6i vulnerability
> ----------------------------------------
>
> Researchers have discovered a timing attack on RSA keys, to which
> OpenSSL is generally vulnerable, unless RSA blinding has been turned
> on.
>
> Typically, it will not have been, because it is not easily possible to
> do so when using OpenSSL to provide SSL or TLS.
>
> The enclosed patch switches blinding on by default. Applications that
> wish to can remove the blinding with RSA_blinding_off(), but this is
> not generally advised. It is also possible to disable it completely by
> defining OPENSSL_NO_FORCE_RSA_BLINDING at compile-time.
>
> The performance impact of blinding appears to be small (a few
> percent).
>
> This problem affects many applications using OpenSSL, in particular,
> almost all SSL-enabled Apaches. You should rebuild and reinstall
> OpenSSL, and all affected applications.
>
> The Common Vulnerabilities and Exposures project (cve.mitre.org) has
> assigned the name CAN-2003-0147 to this issue.
>
> We strongly advise upgrading OpenSSL in all cases, as a precaution.
> ----
>
> Index: crypto/rsa/rsa_eay.c
> ===================================================================
> RCS file: /e/openssl/cvs/openssl/crypto/rsa/rsa_eay.c,v
> retrieving revision 1.28.2.3
> diff -u -r1.28.2.3 rsa_eay.c
> --- crypto/rsa/rsa_eay.c 30 Jan 2003 17:37:46 -0000 1.28.2.3
> +++ crypto/rsa/rsa_eay.c 16 Mar 2003 10:34:13 -0000
> @@ -195,6 +195,25 @@
> return(r);
> }
>
> +static int rsa_eay_blinding(RSA *rsa, BN_CTX *ctx)
> + {
> + int ret = 1;
> + CRYPTO_w_lock(CRYPTO_LOCK_RSA);
> + /* Check again inside the lock - the macro's check is racey */
> + if(rsa->blinding == NULL)
> + ret = RSA_blinding_on(rsa, ctx);
> + CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
> + return ret;
> + }
> +
> +#define BLINDING_HELPER(rsa, ctx, err_instr) \
> + do { \
> + if(((rsa)->flags & RSA_FLAG_BLINDING) && \
> + ((rsa)->blinding == NULL) && \
> + !rsa_eay_blinding(rsa, ctx)) \
> + err_instr \
> + } while(0)
> +
> /* signing */
> static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
> unsigned char *to, RSA *rsa, int padding)
> @@ -239,8 +258,8 @@
> goto err;
> }
>
> - if ((rsa->flags & RSA_FLAG_BLINDING) && (rsa->blinding == NULL))
> - RSA_blinding_on(rsa,ctx);
> + BLINDING_HELPER(rsa, ctx, goto err;);
> +
> if (rsa->flags & RSA_FLAG_BLINDING)
> if (!BN_BLINDING_convert(&f,rsa->blinding,ctx)) goto err;
>
> @@ -318,8 +337,8 @@
> goto err;
> }
>
> - if ((rsa->flags & RSA_FLAG_BLINDING) && (rsa->blinding == NULL))
> - RSA_blinding_on(rsa,ctx);
> + BLINDING_HELPER(rsa, ctx, goto err;);
> +
> if (rsa->flags & RSA_FLAG_BLINDING)
> if (!BN_BLINDING_convert(&f,rsa->blinding,ctx)) goto err;
>
> Index: crypto/rsa/rsa_lib.c
> ===================================================================
> RCS file: /e/openssl/cvs/openssl/crypto/rsa/rsa_lib.c,v
> retrieving revision 1.30.2.2
> diff -u -r1.30.2.2 rsa_lib.c
> --- crypto/rsa/rsa_lib.c 30 Jan 2003 17:37:46 -0000 1.30.2.2
> +++ crypto/rsa/rsa_lib.c 16 Mar 2003 10:34:13 -0000
> @@ -72,7 +72,13 @@
>
> RSA *RSA_new(void)
> {
> - return(RSA_new_method(NULL));
> + RSA *r=RSA_new_method(NULL);
> +
> +#ifndef OPENSSL_NO_FORCE_RSA_BLINDING
> + r->flags|=RSA_FLAG_BLINDING;
> +#endif
> +
> + return r;
> }
>
> void RSA_set_default_method(const RSA_METHOD *meth)
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