Padding in 128 EIA-3
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Padding in 128 EIA-3
zeshan Thu Feb 03, 2011 9:42 pm
Hi,
My queries regarding padding of 128-EIA3 are as follows:-
1. Is Padding a bit 1 is necessary in 128-EIA3 as it is mentioned in document 4 but document 1 has no in formation regarding it.
2.What is the cryptographic importance of a Padding a bit 1.
3.What is the value of padded bit either 0 or 1.
4.Is length of padded bit is included in variable LENGTH or it is just an extra bit.
Regards
My queries regarding padding of 128-EIA3 are as follows:-
1. Is Padding a bit 1 is necessary in 128-EIA3 as it is mentioned in document 4 but document 1 has no in formation regarding it.
2.What is the cryptographic importance of a Padding a bit 1.
3.What is the value of padded bit either 0 or 1.
4.Is length of padded bit is included in variable LENGTH or it is just an extra bit.
Regards
zeshan- Posts : 11
Join date : 2010-08-16
Re: Padding in 128 EIA-3
Peng Wang Mon Feb 07, 2011 3:47 pm
>1. Is Padding a bit 1 is necessary in 128-EIA3 as it is mentioned in document 4 but document 1 has no in formation regarding it.
Yes, it is necessary in 128-EIA3. The core of 128-EIA3 is a univesal hash funtion and the padding is a part of the universal hash function. The MAC value is generated by one-time-pad masking of the univeral hashing value. The descryption of document 4 and document 1 is not consistent.
>2.What is the cryptographic importance of a Padding a bit 1.
Without padding, the uinversal hash function is not AXU (Almost XOR Universal) and can not handle variable-input-length messages.
>3.What is the value of padded bit either 0 or 1.
The Padding bit is 1 for any message.
>4.Is length of padded bit is included in variable LENGTH or it is just an extra bit.
Extra bit.
PS.
Since a bad mask was used in the former version of 128-EIA3 and a forgery attack was presented by Thomas Fuhr et al [FGRV10], a minor modification was made in the newest version of 128-EIA3.
[FGRV10] Thomas Fuhr, Henri Gilbert, Jean-René Reinhard, and Marion Videau, A forgery attack on the candidate LTE integrity algorithm 128-EIA3, http://eprint.iacr.org/2010/618.
Yes, it is necessary in 128-EIA3. The core of 128-EIA3 is a univesal hash funtion and the padding is a part of the universal hash function. The MAC value is generated by one-time-pad masking of the univeral hashing value. The descryption of document 4 and document 1 is not consistent.
>2.What is the cryptographic importance of a Padding a bit 1.
Without padding, the uinversal hash function is not AXU (Almost XOR Universal) and can not handle variable-input-length messages.
>3.What is the value of padded bit either 0 or 1.
The Padding bit is 1 for any message.
>4.Is length of padded bit is included in variable LENGTH or it is just an extra bit.
Extra bit.
PS.
Since a bad mask was used in the former version of 128-EIA3 and a forgery attack was presented by Thomas Fuhr et al [FGRV10], a minor modification was made in the newest version of 128-EIA3.
[FGRV10] Thomas Fuhr, Henri Gilbert, Jean-René Reinhard, and Marion Videau, A forgery attack on the candidate LTE integrity algorithm 128-EIA3, http://eprint.iacr.org/2010/618.
Peng Wang- Posts : 6
Join date : 2010-10-25
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