Package org.cryptomator.cryptolib.api

Interface FileContentCryptor

public interface FileContentCryptor

Method Summary

Modifier and Type	Method	Description
boolean	canSkipAuthentication()
int	ciphertextChunkSize()
default long	ciphertextSize(long cleartextSize)	Calculates the size of the ciphertext resulting from the given cleartext encrypted with the given cryptor.
int	cleartextChunkSize()
default long	cleartextSize(long ciphertextSize)	Calculates the size of the cleartext resulting from the given ciphertext decrypted with the given cryptor.
ByteBuffer	decryptChunk(ByteBuffer ciphertextChunk, long chunkNumber, FileHeader header, boolean authenticate)	Decrypts a single chunk of ciphertext.
void	decryptChunk(ByteBuffer ciphertextChunk, ByteBuffer cleartextChunk, long chunkNumber, FileHeader header, boolean authenticate)	Decrypts a single chunk of ciphertext.
ByteBuffer	encryptChunk(ByteBuffer cleartextChunk, long chunkNumber, FileHeader header)	Encrypts a single chunk of cleartext.
void	encryptChunk(ByteBuffer cleartextChunk, ByteBuffer ciphertextChunk, long chunkNumber, FileHeader header)	Encrypts a single chunk of cleartext.

Method Detail

canSkipAuthentication

boolean canSkipAuthentication()

Returns:

true if it is technically possible to decrypt unauthentic ciphertext

cleartextChunkSize

int cleartextChunkSize()

Returns:

The number of cleartext bytes per chunk.

ciphertextChunkSize

int ciphertextChunkSize()

Returns:

The number of ciphertext bytes per chunk.

encryptChunk

ByteBuffer encryptChunk(ByteBuffer cleartextChunk,
                        long chunkNumber,
                        FileHeader header)

Encrypts a single chunk of cleartext.

Parameters:

cleartextChunk - Content to be encrypted

chunkNumber - Number of the chunk to be encrypted

header - Header of the file, this chunk belongs to

Returns:

Encrypted content.

encryptChunk

void encryptChunk(ByteBuffer cleartextChunk,
                  ByteBuffer ciphertextChunk,
                  long chunkNumber,
                  FileHeader header)

Encrypts a single chunk of cleartext.

Parameters:

cleartextChunk - Content to be encrypted

ciphertextChunk - Encrypted content buffer (with at least ciphertextChunkSize() remaining bytes)

chunkNumber - Number of the chunk to be encrypted

header - Header of the file, this chunk belongs to

decryptChunk

ByteBuffer decryptChunk(ByteBuffer ciphertextChunk,
                        long chunkNumber,
                        FileHeader header,
                        boolean authenticate)
                 throws AuthenticationFailedException

Decrypts a single chunk of ciphertext.

Parameters:

ciphertextChunk - Content to be decrypted

chunkNumber - Number of the chunk to be decrypted

header - Header of the file, this chunk belongs to

authenticate - Skip authentication by setting this flag to false. Should always be true by default.

Returns:

Decrypted content. Position is set to 0 and limit to the end of the chunk.

Throws:

AuthenticationFailedException - If authenticate is true and the given chunk does not match its MAC.

UnsupportedOperationException - If authenticate is false but this cryptor can not skip authentication.

decryptChunk

void decryptChunk(ByteBuffer ciphertextChunk,
                  ByteBuffer cleartextChunk,
                  long chunkNumber,
                  FileHeader header,
                  boolean authenticate)
           throws AuthenticationFailedException

Decrypts a single chunk of ciphertext.

Parameters:

ciphertextChunk - Content to be decrypted

cleartextChunk - Buffer for decrypted chunk (with at least cleartextChunkSize() remaining bytes)

chunkNumber - Number of the chunk to be decrypted

header - Header of the file, this chunk belongs to

authenticate - Skip authentication by setting this flag to false. Should always be true by default.

Throws:

AuthenticationFailedException - If authenticate is true and the given chunk does not match its MAC.

UnsupportedOperationException - If authenticate is false but this cryptor can not skip authentication.

cleartextSize

default long cleartextSize(long ciphertextSize)

Calculates the size of the cleartext resulting from the given ciphertext decrypted with the given cryptor.

Parameters:

ciphertextSize - Length of encrypted payload. Not including the length of the header.

Returns:

Cleartext length of a ciphertextSize-sized ciphertext decrypted with cryptor.

ciphertextSize

default long ciphertextSize(long cleartextSize)

Calculates the size of the ciphertext resulting from the given cleartext encrypted with the given cryptor.

Parameters:

cleartextSize - Length of a unencrypted payload.

Returns:

Ciphertext length of a cleartextSize-sized cleartext encrypted with cryptor. Not including the length of the header.