public IvParameterSpec (byte[] iv, int offset, int len)

Creates an IvParameterSpec object using the first len bytes in iv, beginning at offset inclusive, as the IV.

The bytes that constitute the IV are those between iv[offset] and iv[offset+len-1] inclusive.

iv    the buffer with the IV. The first len bytes of the buffer beginning at offset inclusive are copied to protect against subsequent modification.
offset    the offset in iv where the IV starts.
len    the number of IV bytes.

IllegalArgumentException    if iv is null or (iv.length - offset < len)
ArrayIndexOutOfBoundsException    is thrown if offset or len index bytes outside the iv.