Then give it a valid input file! Your program needs a file that consists of a sequence of "packed" int objects, but you didn't provide such a file. Put differently, you need a file whose size is a multiple of sizeof(int).

Or, from the other perspective, you wrote a program that needs a file whose size is a multiple of sizeof(int), but that's not what the program should expect.

When using a block ciphers on a stream of arbitrary length, a padding algorithm is used to make the input size a multiple of the block size before encryption.

In your case, you could use the following: 

my $padding_len = $int_size - ( length( $buf ) % $int_size );

my $padding = ( "\x00" x ( $padding_len - 1 ) ) . chr( $padding_len );

$buf .= $padding;

[download]

After decrypting, you remove the padding by removing an amount of bytes equal to the value of the last bytes. 

$buf = substr( $buf, 0, -ord( substr( $buf, -1 ) ) );

[download]

In reply to Re^4: binmode copy loses final byte by ikegami
in thread binmode copy loses final byte by aplonis

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