Hello,
On Jul 6, 2010, at 2:04 PM, Jean-Michel Pouré - GOOZE wrote:
> I try to understand how many keys/certificates can be stored in a
> smartcard. Usually vendor specs say "32k, 64k" space on smartcard.
Some of that space (if if they advertise 32K, ir ptobably has a 32K EEPROM
chip) may not be available for external use.
> From my test, it appears that when a smartcard is full, you cannot
> transfert RSA keys or certificates.
That makes sense, no?
> Would it be possible for OpenSC to display available space left on
> device? Or the number of RSA keys / X.509 certs which can be stored.
Patches are welcome. EF(UnusedSpace) could be the starting pointer in PKCS#15.
> Another question: how do we know in advance how much space is used by
> RSA keys and X.509 certificates? Are there tips to calculate this fast?
If you import keys from a host system, convert the PEM to DER and use ls -l,
add some ("few") bytes for internal bookkeeping and you get the rough size that
gets used on the card. The same applies to on-board key generation. You know
the size in bits of the keys and probably there is some extra space used for
internal bookkeeping.
--
Martin Paljak
@martinpaljak.net
+3725156495
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