[Cryptography Team] CTR mode, SecureRandom, ElGamal updates

[satru pakala]

Hi,
I am new to this group. I have a question about generation of cryptographic
keys.
Is it possible to generate public and private keys from a String? i mean
what i am doing is i am taking a fingrprint image and i am converting it to
Stirng then from that string i have to generate keys.i don't know whether we
can do like that or not? Please tell me is there anyway to generate keys
from an inputted image or a Stirng or array of bytes?
Thanks,
Pakala


On 2/16/06, luciano <luchiano at gmail.com> wrote:
>
> Nice! Thanks!
> Wow, the generation of the 2048-bit key takes 10 hours? I'll see if I
> can improve that.
>
> Luciano
>
> On 2/16/06, Chris Muller <chris at funkyobjects.org> wrote:
> > Hi, this is just note to keep everyone informed about
> > what I've done.  Sorry its long, I will try to keep it
> > newsworthy and dense.   I have begun committing my
> > initial Cryptography improvements as promised.  I just
> > committed the following to our repository:
> >
> > For CryptographyBase:
> >
> > - Updated all usages of standard Random to use
> > SecureRandom.  This now allows calculation of 512,
> > 1024, 2048 and, computational power permitting, larger
> > keys.  According to Schneier, Ferguson - "Practical
> > Cryptography" p. 217:
> >         "A prime of 2048 bits can be expected to secure data
> > until around 2022; 3072 bits is secure until 2038; and
> > 4096 bits until 2050." ...  "Be careful with these
> > kinds of predictions."
> >
> > - Extended SecureRandom with #nextInt: and
> > #nextFrom:to:.  The implementation just keeps calling
> > nextBits: until an in-range is returned, and it passed
> > a simple dispersion test.
> >
> > - As a substitute for Collection
> > class>>#randomForPicking, we now have SecureRandom
> > class>>#picker.  This keys of this are wiped out and
> > regenerated on every image save, since saving the key
> > to disk is not recommended.
> >
> > - Added SecureRandom class>>#withGeneratedKey.  This
> > enumerates a series of relatively unpredictable
> > Strings such as the bitmap of the current Squeak
> > desktop, mouse position, Timer values, etc.
> >
> > - Fixed printOn:
> >
> >
> > For Cryptography-Core:
> >
> > - Addition of CTR (counter) cipher mode.  In
> > "Practical Cryptography" Schneier reasons this is
> > preferred mode due to its simple implementation and no
> > need for padding.
> >
> > - Added LargePositiveInteger>>#destroy to permit
> > wiping of keys from the image at proper times.
> >
> >
> > For Cryptography-ElGamal
> >
> > - Now using SecureRandom instead of (insecure) Random.
> >
> >
> > For Cryptography-Tests
> >
> > - The ElGamal cryptography tests let us down in terms
> > of testing for practical usage.  They were using
> > 15-bit keys which totally obscured the problem with
> > the Random, which could not even generate numbers
> > large enough for the primes associated with 2048-bit
> > asymmetric keys (not to mention 1024 and 512!).
> > Therefore, I upgraded the tests to use 384
> > (generated), 512, 1024, 2048 bit ElGamal keys.  The
> > 2048-bit took 10 hours (!!) to generate, so I
> > instantiate with its #storeString so that the tests
> > run quickly.
> >
> > - Also beefed up the associated DiffieHellman test to
> > use 384 bit keys (probably should test these with the
> > same key sizes as ElGamel).
> >
> > - Because of the enhanced tests, there are more
> > methods, so I recategorized according to what they are
> > testing; "ElGamal", "DSA", "RSA", etc.  However, I'm
> > beginning to think we should move these tests to their
> > individual packages of what they're testing.  What
> > does everyone else think?
> >
> > That's all for now, I hope you like it..!
> >
> >  - Chris
> > _______________________________________________
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> > http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/cryptography
> >
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