[Ach] about the 3DES thing again
azet at azet.org
Tue Dec 3 14:19:52 CET 2013
We’re aware of that and that’s basically the reason why we excluded them from our TLS configurations.
My issue still being: Why include a paragraph on 3DES then anyways? I think that’s pretty useless. And does not apply to TLS/SSL.
On 03 Dec 2013, at 14:15, ianG <iang at iang.org> wrote:
> The problem with t-des in all of its variants is that it is a 64 bit block cipher. This makes it vulnerable to rainbow tables, which puts a ceiling on its overall security.
> Modern ciphers are typically 128 bit block sizes. In March at FSE, DJB was opining that even 128 bits may be too small...
> So, t-des and des and *all 64 bit block ciphers* and their variants are more or less deprecated.
> On 3/12/13 02:41 AM, Aaron Zauner wrote:
>> I gave some thought to what we discussed during the meeting. To keep people on track: We were talking whether we should add or remove the paragraph on 3DES that currently states:
>> One special remark is necessary for 3DES: here we want to note
>> that it theoretically has 168 bit security, however based on the NIST Special
>> Publication 800-57
>> pages 63 and 64}, it is clear that 3DES is only considered 80 bits / 112 bits.
>> This needs further discussion and feedback from other people on the ML.
>> My opinion:
>> 1) We are critical of NIST (a bit too critical in my opinion) - yet we include a reference to a NIST publication citing security concerns with 1 or 2 key variants of 3DES (usually 3 keys for each iteration, yielding 168bit security)
>> 2) I cannot find any popular SSLv3 library implementing 3DES with only one or two keys.   
>> 3) So after all.. we exclude 3DES in example configurations, why include a statement on 3DES implementations that are not relevant to the paper? I’m sure they are out there. But they do not matter for us, right?
>>  - https://github.com/openssl/openssl/blob/master/crypto/des/des_enc.c
>> - https://github.com/openssl/openssl/blob/master/crypto/des/des.h
>> void DES_ede3_cbcm_encrypt(const unsigned char *in,unsigned char *out,
>> long length,
>> DES_key_schedule *ks1,DES_key_schedule *ks2,
>> DES_key_schedule *ks3,
>> DES_cblock *ivec1,DES_cblock *ivec2,
>> int enc);
>>  - https://polarssl.org/des-source-code
>> #define DES_KEY_SIZE 8
>> typedef struct
>> int mode; /*!< encrypt/decrypt */
>> uint32_t sk; /*!< 3DES subkeys */
>>  - http://git.savannah.gnu.org/cgit/gnutls.git/tree/lib/nettle/cipher.c?id=0d004a210db5d220c896456a165c81264fa4454a#n76
>> - http://git.lysator.liu.se/nettle/nettle/blobs/master/des3.c#line36
>> des3_set_key(struct des3_ctx *ctx, const uint8_t *key)
>> unsigned i;
>> int is_good = 1;
>> for (i = 0; i<3; i++, key += DES_KEY_SIZE)
>> if (!des_set_key(&ctx->des[i], key))
>> is_good = 0;
>> return is_good;
>> Ach mailing list
>> Ach at lists.cert.at
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