You can use unpack. But unless you're already a pack/unpack wizard, it will take you about 10 times longer to figure out the magical unpack formula than, for example, the following simple solution:

my $key = "0123456789ABCDEF0123456789ABCDEF";

my @b = map { chr hex $_ } $key =~ /(..)/g;
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Not quite. There are three bugs in your code:

• Incorrect results are returned when the most significant bit is set. A sign bit should be added, adding an extra byte. *
  "FFFF" should return ("\x00", "\xFF", "\xFF").

• Incorrect results are returned when there are leading zeroes.
  "000102" should return ("\x01", "\x02").

• Incorrect results are returned when an odd number of hex digits are provided.
  "102" should return ("\x01", "\x02").

Relevant docs:
java.Math.BigInteger.BigInteger(java.lang.String, int)
java.Math.BigInteger.toByteArray()
java.Math.BigInteger.bitLength()

Fixed code:

my $key = "0123456789ABCDEF0123456789ABCDEF";

local $_ = $key;
s/^0+//;
$_ = "0$_" if length % 2 == 1;
$_ = "00$_" if /^[89ABCDEFabcdef]/;
my @b = map { chr hex $_ } /(..)/g;
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* – I'm assuming new BigInteger("FFFF", 16) is considered to be 65535 (not -1).

Thanks for the reply
, Please let me know what I should read to get familiar with these ( I do not have much computer background ).
when i print the java output (each element of the array) I get the following result ..

1 35 69 103 -119 -85 -51 -17 1 35 69 103 -119 -85 -51 -17


The perl one gives this output

1 35 69 103 137 171 205 239 1 35 69 103 137 171 205 239

Could you explain for those who don't know how to read Java what it does? A description of the actual problem would enable more people here to respond with better accuracy.

Thanks for your reply
I am not very familiar with Java but here goes
From the javadoc


BigInteger(String val, int radix) Translates the String representation of a BigInteger in the specified radix into a BigInteger.


toByteArray() Returns a byte array containing the two's-complement representation of this BigInteger.

I don't know about the toByteArray() method, but the conversion to a BigInteger-like object could be handled by Math::BigInt. You could then use standard algorithms for dividing an integer into bytes, I suppose.