Mapping between ecncryption algorithms in Javacard 2.1.1 and J2Se 1.4

Question

Hi!
I would like to encrypt a string using javax.crypto.Cipher (in J2SE 1.4.2) with DES key and decrypt it using javacardx.crypto.Cipher in a javacard 2.1.1. I am unable to figure to the appropriate algorthim/mode/padding in J2SE 1.4 with constant in javacardx.crypto.Cipher object.
Specifically, if I want use javacardx.crypto.Cipher.ALG_DES_CBC_ISO9797_M2, then what would be appropriate transformation spec for "algorithm/mode/padding" in javax.crypto.Cipher of J2SE 1.4.
Any mapping that is applicable for JCOP 3.0 (i.e. javacard 2.2.1) will be appreciated.
Thanks.

Answer 1

I understood your question well.
Here is an example with "ISO-9797-1 padding method 1" padding on the JavaCard side:
1) the relevant Applet code is:
          case (byte) 0x00:
               // compute the size for the result buffer with the encryption result
               short bufSize = (short)buf[ISO7816.OFFSET_LC];
               short rest;
               if ( ( rest = (short)(buf[ISO7816.OFFSET_LC] % 8) ) > 0 ) {
                    bufSize += rest;
               byte[] outBuff = JCSystem.makeTransientByteArray( bufSize, JCSystem.CLEAR_ON_DESELECT );
               Cipher cipher = Cipher.getInstance( Cipher.ALG_DES_CBC_ISO9797_M1, true );
               DESKey key = ( DESKey )KeyBuilder.buildKey(KeyBuilder.TYPE_DES, KeyBuilder.LENGTH_DES3_2KEY, false );
               key.setKey( keyData, (short)0 );
               cipher.init( key, Cipher.MODE_ENCRYPT );
               cipher.doFinal( buf, ISO7816.OFFSET_CDATA, buf[ISO7816.OFFSET_LC], outBuff, (short)0 );
               Util.arrayCopyNonAtomic( outBuff, (short)0, apdu.getBuffer(), (short)0, (short)outBuff.length );
               apdu.setOutgoingAndSend( (short)0, (short)outBuff.length );
               break;2) the JCShell commands:
cm>  /select A00000000353800001
=> 00 A4 04 00 09 A0 00 00 00 03 53 80 00 01 00       ..........S....
(0 msec)
<= 90 00                                              ..
Status: No Error
cm>  /send 000000000C26123456FFFFFFFFB1B2B3B4
=> 00 00 00 00 0C 26 12 34 56 FF FF FF FF B1 B2 B3    .....&.4V.......
    B4                                                 .
(0 msec)
<= B9 EB E3 27 34 E2 6E C0 F7 13 10 E0 74 8F F0 E8    ...'4.n.....t...
    90 00                                              ..
Status: No Error3) Encrypt the same data with Sun's JSE Cipher. Enlarge the input data to a multiple of 8 and fill the rest with 0x00:
CryptoHelper.cipherBlockCrypt mit:
  code is  : Cipher.getInstance( DESede/CBC/NoPadding );
  Buffer   : 26123456FFFFFFFFB1B2B3B400000000
  Key      : E11987EE331B417A5D67D760692F89D4E11987EE331B417A
  Mode     : Encrypt
  Algorithm: DESede im Modus: CBC with: NoPadding
  Result   : B9EBE32734E26EC0F71310E0748FF0E84) You can also use the ISO-9797-1 padding method 2 an both sides:
a) applet code is:
               Cipher cipher = Cipher.getInstance( Cipher.ALG_DES_CBC_ISO9797_M2, true );b) For the JSE cipher pad your block with one byte 0x80 and the rest with 0x00 like here:
CryptoHelper.cipherBlockCrypt mit:
  code is  : Cipher.getInstance( DESede/CBC/NoPadding );
  Buffer   : 26123456FFFFFFFFB1B2B3B480000000
  Key      : E11987EE331B417A5D67D760692F89D4E11987EE331B417A
  Mode     : Encrypt
  Algorithm: DESede im Modus: CBC with: NoPadding
  Result   : B9EBE32734E26EC09E729797231D2238Is that what you need?!