com.amazonaws.encryptionsdk.model

Class CiphertextHeaders

java.lang.Object

com.amazonaws.encryptionsdk.model.CiphertextHeaders

Direct Known Subclasses:

ParsedCiphertext

public class CiphertextHeaders
extends Object

This class implements the headers for the message (ciphertext) produced by this library. These headers are parsed and used when the ciphertext is decrypted. It contains the following fields in order:

1. version number of the message format
2. type of the object - e.g., Customer Authenticated Encrypted Data
3. algorithm Id - identifier for the algorithm used
4. Message ID - bytes that uniquely identify the message (encrypted content) wrapped by this header
5. Encryption context length- length of the encryption context for encrypting data key
6. Encryption context - encryption context for encrypting data key
7. Encrypted Data key count - count of the encrypted data keys embedded in this object
8. KeyBlob - the KeyBlob containing the key provider, key provider info, encrypted key, and their lengths for each data key
9. ContentType - single-block or framing
10. Reserved field - 4 bytes reserved for future use
11. Nonce length - the length of the nonce used in authenticating this header and encrypting the content it wraps
12. Frame length - length of the frames (when framing)
13. Header nonce - the nonce used in creating the header tag
14. Header tag - the MAC tag created to protect the contents of the header

It is important to note that the header fields 1 through 12 are checked for their integrity during decryption using AES-GCM with the nonce and MAC tag values supplied in fields 13 and 14 respectively.

Constructor Summary

Constructors

Constructor and Description
CiphertextHeaders() Default constructor.
CiphertextHeaders(byte version, CiphertextType type, CryptoAlgorithm cryptoAlgo, byte[] encryptionContext, List<KeyBlob> keyBlobs, ContentType contentType, int frameSize) Construct the ciphertext headers using the provided values.

Method Summary

Modifier and Type	Method and Description
int	deserialize(byte[] b, int off) Deserialize the provided bytes starting at the specified offset to construct an instance of this class.
ContentType	getContentType() Return the content type set in the header.
CryptoAlgorithm	getCryptoAlgoId() Return the crypto algorithm identifier set in the header.
int	getEncryptedKeyBlobCount() Return the count of the encrypted key blobs set in the header.
List<KeyBlob>	getEncryptedKeyBlobs() Return the encrypted key blobs set in the header.
byte[]	getEncryptionContext() Return the encryption context set in the header.
int	getEncryptionContextLen() Return the length of the encryption context set in the header.
Map<String,String>	getEncryptionContextMap()
int	getFrameLength() Return the length of the frame set in the header.
byte[]	getHeaderNonce() Return the header nonce set in the header.
byte[]	getHeaderTag() Return the header tag set in the header.
byte[]	getMessageId() Return the message identifier set in the header.
short	getNonceLength() Return the length of the nonce set in the header.
CiphertextType	getType() Return the type set in the header.
byte	getVersion() Return the version set in the header.
Boolean	isComplete() Check if this object has all the header fields populated and available for reading.
byte[]	serializeAuthenticatedFields() Serialize the header fields into a byte array.
void	setHeaderNonce(byte[] headerNonce) Set the header nonce to use for authenticating the header data.
void	setHeaderTag(byte[] headerTag) Set the header tag to use for authenticating the header data.
byte[]	toByteArray() Serialize the header fields into a byte array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CiphertextHeaders

public CiphertextHeaders()

Default constructor.

CiphertextHeaders

public CiphertextHeaders(byte version,
                         CiphertextType type,
                         CryptoAlgorithm cryptoAlgo,
                         byte[] encryptionContext,
                         List<KeyBlob> keyBlobs,
                         ContentType contentType,
                         int frameSize)

Construct the ciphertext headers using the provided values.

Parameters:

version - the version to set in the header.

type - the type to set in the header.

cryptoAlgo - the CryptoAlgorithm enum to encode in the header.

encryptionContext - the bytes containing the encryption context to set in the header.

keyBlob - the keyBlob object containing the key provider id, key provider info, and encrypted data key to encode in the header.

contentType - the content type to set in the header.

frameSize - the frame payload size to set in the header.

Method Detail

isComplete

public Boolean isComplete()

Check if this object has all the header fields populated and available for reading.

Returns:

true if this object containing the single block header fields is complete; false otherwise.

deserialize

public int deserialize(byte[] b,
                       int off)
                throws ParseException

Deserialize the provided bytes starting at the specified offset to construct an instance of this class.

This method parses the provided bytes for the individual fields in this class. This methods also supports partial parsing where not all the bytes required for parsing the fields successfully are available.

Parameters:

b - the byte array to deserialize.

off - the offset in the byte array to use for deserialization.

Returns:

the number of bytes consumed in deserialization.

Throws:

ParseException

serializeAuthenticatedFields

public byte[] serializeAuthenticatedFields()

Serialize the header fields into a byte array. Note this method does not serialize the header nonce and tag.

Returns:

the serialized bytes of the header fields not including the header nonce and tag.

toByteArray

public byte[] toByteArray()

Serialize the header fields into a byte array. This method serializes all the header fields including the header nonce and tag.

Returns:

the serialized bytes of the entire header.

getVersion

public byte getVersion()

Return the version set in the header.

Returns:

the byte value representing the version.

getType

public CiphertextType getType()

Return the type set in the header.

Returns:

the CiphertextType enum value representing the type set in the header.

getCryptoAlgoId

public CryptoAlgorithm getCryptoAlgoId()

Return the crypto algorithm identifier set in the header.

Returns:

the CryptoAlgorithm enum value representing the identifier set in the header.

getEncryptionContextLen

public int getEncryptionContextLen()

Return the length of the encryption context set in the header.

Returns:

the length of the encryption context set in the header.

getEncryptionContext

public byte[] getEncryptionContext()

Return the encryption context set in the header.

Returns:

the bytes containing encryption context set in the header.

getEncryptionContextMap

public Map<String,String> getEncryptionContextMap()

getEncryptedKeyBlobCount

public int getEncryptedKeyBlobCount()

Return the count of the encrypted key blobs set in the header.

Returns:

the count of the encrypted key blobs set in the header.

getEncryptedKeyBlobs

public List<KeyBlob> getEncryptedKeyBlobs()

Return the encrypted key blobs set in the header.

Returns:

the KeyBlob objects representing the key blobs set in the header.

getContentType

public ContentType getContentType()

Return the content type set in the header.

Returns:

the ContentType enum value representing the content type set in the header.

getMessageId

public byte[] getMessageId()

Return the message identifier set in the header.

Returns:

the bytes containing the message identifier set in the header.

getNonceLength

public short getNonceLength()

Return the length of the nonce set in the header.

Returns:

the length of the nonce set in the header.

getFrameLength

public int getFrameLength()

Return the length of the frame set in the header.

Returns:

the length of the frame set in the header.

getHeaderNonce

public byte[] getHeaderNonce()

Return the header nonce set in the header.

Returns:

the bytes containing the header nonce set in the header.

getHeaderTag

public byte[] getHeaderTag()

Return the header tag set in the header.

Returns:

the header tag set in the header.

setHeaderNonce

public void setHeaderNonce(byte[] headerNonce)

Set the header nonce to use for authenticating the header data.

Parameters:

headerNonce - the header nonce to use.

setHeaderTag

public void setHeaderTag(byte[] headerTag)

Set the header tag to use for authenticating the header data.

Parameters:

headerTag - the header tag to use.