question: @ Override public int doFinal ( final byte [ ] out , final int outOff ) throws BadCiphertextException { complete_ = true ; int written = contentCryptoHandler_ . doFinal ( out , outOff ) ; updateTrailingSignature ( out , outOff , written ) ; if ( cryptoAlgo_ . getTrailingSignatureLength ( ) > 0 ) { try { CiphertextFooters footer = new CiphertextFooters ( trailingSig_ . sign ( ) ) ; byte [ ] fBytes = footer . toByteArray ( ) ; System . arraycopy ( fBytes , 0 , out , outOff + written , fBytes . length ) ; return written + fBytes . length ; } catch ( final SignatureException ex ) { throw new AwsCryptoException ( ex ) ; } } else { return written ; } }
target:  Finish encryption of the plaintext bytes.