Java Card 2.2.2: temporary RSA public key as transitional

Question

I am developing a Java Card applet (2.2.2, thus classic), which, with each use, gets the RSA public key (verified using tools that are not relevant to the question), then use this RSA public key to verify the RSA signature.

How can I save this RSA public key in RAM (instead of writing it to EEPROM / Flash) to increase the performance and life of the device?

My problem is javacard.security.KeyBuilderJC 2.2.2, the buildKey(byte keyType, short keyLength, boolean keyEncryption)API does not seem to be able to specify temporary memory; I don't see either

• suitable combination keyType TYPE_RSA_PUBLICand transcient, as we have with TYPE_DES_TRANSIENT_DESELECT;
• even TYPE_RSA_PRIVATE_TRANSIENT_DESELECT, which could be supposedly abused by the public key (on platforms without d-size verification), for this is the new Java Card Classic 3;
• buildKey(byte algorithmicKeyType, byte keyMemoryType, short keyLength, boolean keyEncryption)with option keyMemoryType, which is also new to Java Card Classic 3.

Will bracketing all changes and using the RSA s public key beginTransaction()and abortTransaction()achieve my goal?

Answer 1

I was dealing with the same problem and had to use read only memory and the level of wear (which worked).

Even with the same idea with beginTransaction()/ abortTransaction(), but the card developer was told that this would not work (they said that it would further worsen the EEPROM lifetime). YMMV.

Some notes:

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• RSAPublicKey, Cipher.

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- API, RSA ( )

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