CODEWITHSUNDEEP
appletjavacard
Jimy25
Jimy25

Reputation: 247

How to calculate NVM size of a java card applet CAP file

Is there any one know how to get NVM (non-volatile memory) of java card applet file?

After researched on the Internet I can't find any tool or guide for this.

Upvotes: 1

Views: 817

Answers (3)

Ujjwal Roy
Ujjwal Roy

Reputation: 550

You can write a function in your applet to return the data related to NVM or RAM using JCSystem APIs.

public static final byte INS_GET_MEMORY = (byte) 0xCB;
public static final short TAG_PERSISTANT_MEM = (short) 0xC602;
public static final short TAG_TRANSIENT_RESET = (short) 0xC702;
public static final short TAG_TRANSIENT_DESELECT = (short) 0xC802;
public static final short TAG_BUFFER_SIZE = (short) 0xC902;
        
private short GetMemory(byte[] apduBuffer) {
    short outDataOffset = ISO7816.OFFSET_CDATA;
        
    outDataOffset = Util.setShort(apduBuffer, outDataOffset, TAG_PERSISTANT_MEM);
        
    // Size is bounded by short limit for Persistent MEMORY_TYPE_PERSISTENT
    // Can use getAvailableMemory(short[] buffer,short offset,byte memoryType)
    // If the size is more than short range
    outDataOffset = Util.setShort(apduBuffer, outDataOffset,
                JCSystem.getAvailableMemory(JCSystem.MEMORY_TYPE_PERSISTENT));
        
    outDataOffset = Util.setShort(apduBuffer, outDataOffset,TAG_TRANSIENT_RESET);
        
    outDataOffset = Util.setShort(apduBuffer, outDataOffset,
                JCSystem.getAvailableMemory(JCSystem.MEMORY_TYPE_TRANSIENT_RESET));
        
    outDataOffset = Util.setShort(apduBuffer, outDataOffset,TAG_TRANSIENT_DESELECT);
        
    outDataOffset = Util.setShort(apduBuffer, outDataOffset,
                JCSystem.getAvailableMemory(JCSystem.MEMORY_TYPE_TRANSIENT_DESELECT));
        
    outDataOffset = Util.setShort(apduBuffer, outDataOffset,TAG_BUFFER_SIZE);
        
    outDataOffset = Util.setShort(apduBuffer, outDataOffset, (short) apduBuffer.length);

    return (short) (outDataOffset - ISO7816.OFFSET_CDATA);


  }

This function return output data length

Upvotes: 0

gaurav_syscom
gaurav_syscom

Reputation: 41

send GET DATA command with Tag DF55 to the card manager (not to applet)

Upvotes: 0

LutfiSeto
LutfiSeto

Reputation: 1

You can send GET DATA APDU command with P1=FF and P2=21, please refer to ETSI 102.226

APDU Command: try this 80 CA FF 21 10

thanks

Upvotes: 0

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