[openssl-users] CBC ciphers + TLS 1.0 protocol does not work in OpenSSL 1.0.2d

[Jayalakshmi bhat]

Hi All,

Is there inputs or suggestions.

Thanks and Regards
Jaya

On Fri, Dec 4, 2015 at 11:37 AM, Jayalakshmi bhat <
bhat.jayalakshmi at gmail.com> wrote:

> Hi Matt,
>
> s3_cbc.c uses the function constant_time_eq_8. I pulled only this
> function definition from OpenSSL 1.0.1e into OpenSSL 1.0.2d. I renamed
> this function as constant_time_eq_8_local and used it in s3_cbc.c instead
> of constant_time_eq_8. This renaming was just to avoid
> multiple definitions.
>
> OpenSSL 1.0.1e has the function constant_time_eq_8 defined as below:
>
> *#define DUPLICATE_MSB_TO_ALL(x) ( (unsigned)( (int)(x) >>
> (sizeof(int)*8-1) ) )#define DUPLICATE_MSB_TO_ALL_8(x) ((unsigned
> char)(DUPLICATE_MSB_TO_ALL(x)))*
>
> *static unsigned char constant_time_eq_8(unsigned a, unsigned b)*
> * {*
> * unsigned c = a ^ b;*
> * c--;*
> * return DUPLICATE_MSB_TO_ALL_8(c);*
> * }*
>
> OpenSSL 1.0.2d has the function constant_time_eq_8 defined as below.
>
> static inline unsigned int constant_time_msb(unsigned int a)
> {
>     return 0 - (a >> (sizeof(a) * 8 - 1));
> }
>
> static inline unsigned int constant_time_is_zero(unsigned int a)
> {
>     return constant_time_msb(~a & (a - 1));
> }
>
> static inline unsigned int constant_time_eq(unsigned int a, unsigned int b)
> {
>     return constant_time_is_zero(a ^ b);
> }
>
> static inline unsigned char constant_time_eq_8(unsigned int a, unsigned
> int b)
> {
>     return (unsigned char)(constant_time_eq(a, b));
> }
>
>
> Regards
> Jaya
>
> On Fri, Dec 4, 2015 at 7:04 PM, Matt Caswell <matt at openssl.org> wrote:
>
>>
>>
>> On 04/12/15 11:31, Jayalakshmi bhat wrote:
>> > Hi Matt,
>> >
>> > Thanks a lot for the response.
>> >
>> > Is your application a client or a server? Are both ends using
>> > OpenSSL 1.0.2d? If not, what is the other end using?
>> >>>Our device has both TLS client,server apps. As client, device
>> communicates with radius server, LDAP server etc.As
>> > server device is accessed using various web browsers.
>> > Hence both the end will not be OpenSSL 1.0.2d.
>> >
>> > How exactly are you doing that? Which specific cipher are you seeing
>> fail?
>> >>> We have provided user option to select TLS protocol versions similar
>> to the browsers. Depending upon the user configurations we set the protocol
>> flags (SSL_OP_NO_TLSv1,SSL_OP_NO_TLSv1_1, SSL_OP_NO_TLSv1_2) in the SSL
>> context using SSL_CTX_clear_options/SSL_CTX_set_options.
>> >>> We have provided user option to chose ciphers as well.
>> > All these are in the application space,no changes have been done and
>> > they have been working good with OpenSSL 1.0.1c. Only the library is
>> > upgraded to OpenSSL 1.0.2d.I have used AES256-CBC and AES128 CBC ciphers
>> > and with both the ciphers issue is seen.
>> >
>> > Are you able to provide a packet capture?
>> >>> Please find the attached traces for server mode.
>> > What O/S is this on?
>> >>>This is built for WinCE and Vxworks
>>
>> Thanks. Please could you also send the exact patch that you applied that
>> resolved the issue?
>>
>> Matt
>> _______________________________________________
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>>
>
>
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