Bignum multiplication improvement for ARM
For Gnuk, it is good to speed up RSA routine.
Last week, I improved a bit. Digital signing by Gnuk, it took 1.78 second (in version 0.12). With the change, it takes 1.72 second. (Majored by time command for gpg --clearsign. It includes calculation time on host and communication time.)
Then, I improved more. With the change, it takes 1.63 second.
Futher, I improved more. With today's change, it takes 1.54 second.
More, I improved. For Gnuk specific version, it just takes 1.48 second.
To be summarized:
- Use UMULL (32-bitx32-bit => 64-bit) instead of UMULAL (mul and accumulate)
- Loading/storing with more registers using LDM and STM
- Use GCC constraints for registers, condition code, and memory
Note that it's 2048-bit RSA computation. Therefore, it is 1024-bit by 1024-bit multiplication because of CRT. For such a not so long size, Karatsuba (or any divide-and-conquer strategy) doesn't make sense, but tuning in assembly language is important.
Here is the ticket of mine: http://polarssl.org/trac/ticket/26
2.5-inch SATA HDD to eSATA/USB2 adopter
本日もジャンク買いの銭失い。
- 千石通商 2号店
- 790 JPY
- Made in China
コネクタに特徴あり。eSATA と USB のコネクタを一つで兼ねるそうです。
2.5インチの SATA HDD を eSATA でも USB でもつなぐことができるアダプタだと思って買った。
試そうとしたら...
そもそも 2.5-inch の SATA のドライブを持ってなかった。ギャフン。
As I encounter a trouble with Gnuk Token, I sent a post to GnuPG-devel.
"CHANGE REFERENCE DATA" is the command for changing password. I think that there is a bug in the specification, which should be improved.
Specifically, the card/token which follows this specification has no way to detect erroneous password input when a part of input is as same as correct password.
The data should have a delimiter or length of input to check input against correct password.
Excerpt of specification
In the section 7.2.3 CHANGE REFERENCE DATA says:
The length of the existing password is known in the card, so that neither a delimiter nor padding for filling up fixed formats is necessary.
It sounds right, but it is not in fact.
Scute ITP
I submitted ITP (Intent To Package) for scute one month before. It is #615930.
#615930: ITP: scute -- OpenPGP smartcard plugin for Mozilla Network Security Services
On 2011-04-10, it was approved and it is in main now.
See Scute PTS page for the package information.