What you may be missing is the "data padding" stuff, which makes the encrypted payload somewhat longer than just what you pass off to the encoding routine. IIRC it throws an 8-sided die and prepends to the messate either
01
02 02
03 03 03
...
08 08 08 08 08 08 08 08
also there may be some length fields or something -- consider the fact that the message "0" will ALWAYS encrypt as "0" while the message "1" will ALWAYS encrypt as "1" (!) so you REALLY DO want to mix in some (at-end-ignorable) randomness. If nothing else, to prevent computing the cyphertext of all possible 64 bit messages into a decrypt dictionary. This is a brute force technique to be sure, but it is doable...
Jesse Hammons wrote:
Jesse Hammons wrote:
So to clarify: If I generate a 65-bit key, will I be able to use that 65-bit key to sign any 64-bit value?
Yes, but
Actually, I have found the answer to be "no" :-)
a 65 bit key won't be very secure AT ALL, it will be very easy to factor a modulus that small.
Security is not my goal. This is more of a theoretical exercise that happens to have a practical application for me.
Bottom line: asymmetrical (public-key) encryption has a fairly large "minimum block size" that actually increases as key size increases.
Indeed. I have found experimentally that: * The minimum signable data quantity in OpenSSL is 1 byte * The minimum size RSA key that can be used to sign 1 byte is 89 bits * A signature created using a 64-bit RSA key would create a number 64 bits long, BUT: - This is not possible to do in OpenSSL because the maximum signable quantity for a 64 bit RSA key is only a few bits, and OpenSSL input/output is done on byte boundaries
Do those number sound right?
Thanks, -Jesse
______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED]
-- "An Internet-connected Windows machine is tantamount to a toddler carrying a baggie of $100 bills down a city street..."
Charles B (Ben) Cranston mailto: [EMAIL PROTECTED] http://www.wam.umd.edu/~zben
______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED]
