Hi everyone,
I was juz discussing with my pals the other day on the appropriate initial
input bit size to seed a PRNG of the structure below for it to be used to
generate the random bits for RSA key material of modulus 1024 bits or 2048
bits. Anyone know what would be the ideal length/size of A so that there is
sufficient entropy to generate the key material for RSA 1024/2048 bits keys?
A: Initial input seed of x bit size and fed into the 3DES x9.17 PRNG in 64
bit blocks.
B: A constant key of 128 bits (112 bits effective). Does not change with
each loop of output block O.
C: Initialization vector - 64 bits size with initial fixed value and fed
back with each loop.
O: Output of 64 bit block with each loop for RSA 1024/2048 key material.
Initial total of x bits as seed
(feeding in 64-bit block feed)
A
|
\|/
x9.17 PRNG V
----------------------
| |
| |<------ B (128bits with 112 bits effective) : Constant
value for all loops
| |
| 3DES |
| |
| |<-------
| | |
---------------------- |
| | | C (64 bit IV) : Initial fixed IV.
Changed/feedback with every loop.
| | |
| -----------|
|
\|/
V
O
Output Random Stream
(in 64 bit blocks)
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Received on Apr 22 2004
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