KnownLengthOutputEncryptor (Bouncy Castle Library 1.85 API Specification)

All Superinterfaces:

OutputEncryptor
```
public interface KnownLengthOutputEncryptor
extends OutputEncryptor
```
Extension of OutputEncryptor for encryptors that can predict the exact ciphertext length produced for a given plaintext length. This enables definite-length (DL/DER) streaming of CMS structures: the encrypted-content OCTET STRING's length has to be written before any ciphertext flows, so the producer needs the count up front.
For encryptors that do not implement this interface the CMS stream generators fall back to deriving the count from the encryptor's algorithm identifier where the algorithm is recognised; implement this interface to support definite-length output with algorithms outside that set.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`long`	`getOutputLength(long inputLength)`	Return the exact number of ciphertext octets that encrypting `inputLength` plaintext octets will produce, including any appended AEAD tag where the CMS structure carries the tag inside the encrypted content.

Methods inherited from interface org.bouncycastle.operator.OutputEncryptor
getAlgorithmIdentifier, getKey, getOutputStream

- Method Detail
  - getOutputLength
```
long getOutputLength(long inputLength)
```
    Return the exact number of ciphertext octets that encrypting inputLength plaintext octets will produce, including any appended AEAD tag where the CMS structure carries the tag inside the encrypted content.
    
    Parameters:
    
    inputLength - number of plaintext octets to be encrypted
    
    Returns:
    
    the exact ciphertext octet count, or -1 if it cannot be determined