Crypto++ 8.5 Free C++ class library of cryptographic schemes

Classes | Public Member Functions | List of all members
AuthenticatedSymmetricCipher Class Referenceabstract

Interface for authenticated encryption modes of operation. More...

Inheritance diagram for AuthenticatedSymmetricCipher:

## Classes
class | BadState
| Exception thrown when the object is in the wrong state for the operation. More...

## Public Member Functions
virtual lword | MaxHeaderLength () const =0
| Provides the maximum length of AAD that can be input. More...
virtual lword | MaxMessageLength () const =0
| Provides the maximum length of encrypted data. More...
virtual lword | MaxFooterLength () const
| Provides the maximum length of AAD. More...
virtual bool | NeedsPrespecifiedDataLengths () const
| Determines if data lengths must be specified prior to inputting data. More...
void | SpecifyDataLengths (lword headerLength, lword messageLength, lword footerLength=0)
| Prescribes the data lengths. More...
virtual void | EncryptAndAuthenticate (byte *ciphertext, byte *mac, size_t macSize, const byte *iv, int ivLength, const byte *header, size_t headerLength, const byte *message, size_t messageLength)
| Encrypts and calculates a MAC in one call. More...
virtual bool | DecryptAndVerify (byte *message, const byte *mac, size_t macSize, const byte *iv, int ivLength, const byte *header, size_t headerLength, const byte *ciphertext, size_t ciphertextLength)
| Decrypts and verifies a MAC in one call. More...
virtual std::string | AlgorithmName () const
| Provides the name of this algorithm. More...
Public Member Functions inherited from SimpleKeyingInterface
virtual size_t | MinKeyLength () const =0
| Returns smallest valid key length. More...
virtual size_t | MaxKeyLength () const =0
| Returns largest valid key length. More...
virtual size_t | DefaultKeyLength () const =0
| Returns default key length. More...
virtual size_t | GetValidKeyLength (size_t keylength) const =0
| Returns a valid key length for the algorithm. More...
virtual bool | IsValidKeyLength (size_t keylength) const
| Returns whether keylength is a valid key length. More...
virtual void | SetKey (const byte *key, size_t length, const NameValuePairs &params=g_nullNameValuePairs)
| Sets or reset the key of this object. More...
void | SetKeyWithRounds (const byte *key, size_t length, int rounds)
| Sets or reset the key of this object. More...
void | SetKeyWithIV (const byte *key, size_t length, const byte *iv, size_t ivLength)
| Sets or reset the key of this object. More...
void | SetKeyWithIV (const byte *key, size_t length, const byte *iv)
| Sets or reset the key of this object. More...
virtual IV_Requirement | IVRequirement () const =0
| Minimal requirement for secure IVs. More...
bool | IsResynchronizable () const
| Determines if the object can be resynchronized. More...
bool | CanUseRandomIVs () const
| Determines if the object can use random IVs. More...
bool | CanUsePredictableIVs () const
| Determines if the object can use random but possibly predictable IVs. More...
bool | CanUseStructuredIVs () const
| Determines if the object can use structured IVs. More...
virtual unsigned int | IVSize () const
| Returns length of the IV accepted by this object. More...
unsigned int | DefaultIVLength () const
| Provides the default size of an IV. More...
virtual unsigned int | MinIVLength () const
| Provides the minimum size of an IV. More...
virtual unsigned int | MaxIVLength () const
| Provides the maximum size of an IV. More...
virtual void | Resynchronize (const byte *iv, int ivLength=-1)
| Resynchronize with an IV. More...
virtual void | GetNextIV (RandomNumberGenerator &rng, byte *iv)
| Retrieves a secure IV for the next message. More...
Public Member Functions inherited from HashTransformation
HashTransformation & | Ref ()
| Provides a reference to this object. More...
virtual void | Update (const byte *input, size_t length)=0
| Updates a hash with additional input. More...
virtual byte * | CreateUpdateSpace (size_t &size)
| Request space which can be written into by the caller. More...
virtual void | Final (byte *digest)
| Computes the hash of the current message. More...
virtual void | Restart ()
| Restart the hash. More...
virtual unsigned int | DigestSize () const =0
| Provides the digest size of the hash. More...
unsigned int | TagSize () const
| Provides the tag size of the hash. More...
virtual unsigned int | BlockSize () const
| Provides the block size of the compression function. More...
virtual unsigned int | OptimalBlockSize () const
| Provides the input block size most efficient for this hash. More...
virtual unsigned int | OptimalDataAlignment () const
| Provides input and output data alignment for optimal performance. More...
virtual void | CalculateDigest (byte *digest, const byte *input, size_t length)
| Updates the hash with additional input and computes the hash of the current message. More...
virtual bool | Verify (const byte *digest)
| Verifies the hash of the current message. More...
virtual bool | VerifyDigest (const byte *digest, const byte *input, size_t length)
| Updates the hash with additional input and verifies the hash of the current message. More...
virtual void | TruncatedFinal (byte *digest, size_t digestSize)=0
| Computes the hash of the current message. More...
virtual void | CalculateTruncatedDigest (byte *digest, size_t digestSize, const byte *input, size_t length)
| Updates the hash with additional input and computes the hash of the current message. More...
virtual bool | TruncatedVerify (const byte *digest, size_t digestLength)
| Verifies the hash of the current message. More...
virtual bool | VerifyTruncatedDigest (const byte *digest, size_t digestLength, const byte *input, size_t length)
| Updates the hash with additional input and verifies the hash of the current message. More...
Public Member Functions inherited from Algorithm
| Algorithm (bool checkSelfTestStatus=true)
| Interface for all crypto algorithms. More...
virtual std::string | AlgorithmProvider () const
| Retrieve the provider of this algorithm. More...
Public Member Functions inherited from Clonable
virtual Clonable * | Clone () const
| Copies this object. More...
Public Member Functions inherited from StreamTransformation
StreamTransformation & | Ref ()
| Provides a reference to this object. More...
virtual unsigned int | MandatoryBlockSize () const
| Provides the mandatory block size of the cipher. More...
virtual unsigned int | OptimalBlockSize () const
| Provides the input block size most efficient for this cipher. More...
virtual unsigned int | GetOptimalBlockSizeUsed () const
| Provides the number of bytes used in the current block when processing at optimal block size. More...
virtual unsigned int | OptimalDataAlignment () const
| Provides input and output data alignment for optimal performance. More...
virtual void | ProcessData (byte *outString, const byte *inString, size_t length)=0
| Encrypt or decrypt an array of bytes. More...
virtual size_t | ProcessLastBlock (byte *outString, size_t outLength, const byte *inString, size_t inLength)
| Encrypt or decrypt the last block of data. More...
virtual unsigned int | MinLastBlockSize () const
| Provides the size of the last block. More...
virtual bool | IsLastBlockSpecial () const
| Determines if the last block receives special processing. More...
void | ProcessString (byte *inoutString, size_t length)
| Encrypt or decrypt a string of bytes. More...
void | ProcessString (byte *outString, const byte *inString, size_t length)
| Encrypt or decrypt a string of bytes. More...
byte | ProcessByte (byte input)
| Encrypt or decrypt a byte. More...
virtual bool | IsRandomAccess () const =0
| Determines whether the cipher supports random access. More...
virtual void | Seek (lword pos)
| Seek to an absolute position. More...
virtual bool | IsSelfInverting () const =0
| Determines whether the cipher is self-inverting. More...
virtual bool | IsForwardTransformation () const =0
| Determines if the cipher is being operated in its forward direction. More...

## Additional Inherited Members
Public Types inherited from SimpleKeyingInterface
enum | IV_Requirement { UNIQUE_IV = 0, RANDOM_IV, UNPREDICTABLE_RANDOM_IV, INTERNALLY_GENERATED_IV, NOT_RESYNCHRONIZABLE }
| Secure IVs requirements as enumerated values. More...

## Detailed Description

Interface for authenticated encryption modes of operation.

AuthenticatedSymmetricCipher() provides the interface for one direction (encryption or decryption) of a stream cipher or block cipher mode with authentication. The StreamTransformation() part of this interface is used to encrypt or decrypt the data. The MessageAuthenticationCode() part of the interface is used to input additional authenticated data (AAD), which is MAC'ed but not encrypted. The MessageAuthenticationCode() part is also used to generate and verify the MAC.

Crypto++ provides four authenticated encryption modes of operation - CCM, EAX, GCM and OCB mode. All modes implement AuthenticatedSymmetricCipher() and the motivation for the API, like calling AAD a "header", can be found in Bellare, Rogaway and Wagner's The EAX Mode of Operation. The EAX paper suggested a basic API to help standardize AEAD schemes in software and promote adoption of the modes.

See also
  Authenticated Encryption on the Crypto++ wiki.

Since
  Crypto++ 5.6.0

Definition at line 1320 of file cryptlib.h.

## Member Function Documentation

## ◆ MaxHeaderLength()

virtual lword AuthenticatedSymmetricCipher::MaxHeaderLength | ( |  | ) | const
| pure virtual

Provides the maximum length of AAD that can be input.

Returns
  the maximum length of AAD that can be input before the encrypted data

Implemented in XChaCha20Poly1305_Base, ChaCha20Poly1305_Base, GCM_Base, CCM_Base, and EAX_Base.

## ◆ MaxMessageLength()

virtual lword AuthenticatedSymmetricCipher::MaxMessageLength | ( |  | ) | const
| pure virtual

Provides the maximum length of encrypted data.

Returns
  the maximum length of encrypted data

Implemented in XChaCha20Poly1305_Base, ChaCha20Poly1305_Base, GCM_Base, CCM_Base, and EAX_Base.

## ◆ MaxFooterLength()

virtual lword AuthenticatedSymmetricCipher::MaxFooterLength | ( |  | ) | const
| inline virtual

Provides the maximum length of AAD.

Returns
  the maximum length of AAD that can be input after the encrypted data

Reimplemented in XChaCha20Poly1305_Base, and ChaCha20Poly1305_Base.

Definition at line 1345 of file cryptlib.h.

## ◆ NeedsPrespecifiedDataLengths()

virtual bool AuthenticatedSymmetricCipher::NeedsPrespecifiedDataLengths | ( |  | ) | const
| inline virtual

Determines if data lengths must be specified prior to inputting data.

Returns
  true if the data lengths are required before inputting data, false otherwise

if this function returns true, SpecifyDataLengths() must be called before attempting to input data. This is the case for some schemes, such as CCM.

See also
  SpecifyDataLengths()

Reimplemented in CCM_Base.

Definition at line 1352 of file cryptlib.h.

## ◆ SpecifyDataLengths()

void AuthenticatedSymmetricCipher::SpecifyDataLengths | ( | lword | headerLength,
|  | lword | messageLength,
|  | lword | footerLength = `0`
| ) |  |

Prescribes the data lengths.

Parameters

  headerLength | size of data before message is input, in bytes
  messageLength | size of the message, in bytes
  footerLength | size of data after message is input, in bytes

SpecifyDataLengths() only needs to be called if NeedsPrespecifiedDataLengths() returns `true`. If `true`, then `headerLength` will be validated against `MaxHeaderLength()`, `messageLength` will be validated against `MaxMessageLength()`, and `footerLength` will be validated against `MaxFooterLength()`.

See also
  NeedsPrespecifiedDataLengths()

## ◆ EncryptAndAuthenticate()

virtual void AuthenticatedSymmetricCipher::EncryptAndAuthenticate | ( | byte * | ciphertext,
|  | byte * | mac,
|  | size_t | macSize,
|  | const byte * | iv,
|  | int | ivLength,
|  | const byte * | header,
|  | size_t | headerLength,
|  | const byte * | message,
|  | size_t | messageLength
| ) |  |
| virtual

Encrypts and calculates a MAC in one call.

Parameters

  ciphertext | the encryption buffer
  mac | the mac buffer
  macSize | the size of the MAC buffer, in bytes
  iv | the iv buffer
  ivLength | the size of the IV buffer, in bytes
  header | the AAD buffer
  headerLength | the size of the AAD buffer, in bytes
  message | the message buffer
  messageLength | the size of the messagetext buffer, in bytes

EncryptAndAuthenticate() encrypts and generates the MAC in one call. The function truncates the MAC if `macSize < TagSize()`.

Reimplemented in XChaCha20Poly1305_Base, and ChaCha20Poly1305_Base.

## ◆ DecryptAndVerify()

virtual bool AuthenticatedSymmetricCipher::DecryptAndVerify | ( | byte * | message,
|  | const byte * | mac,
|  | size_t | macSize,
|  | const byte * | iv,
|  | int | ivLength,
|  | const byte * | header,
|  | size_t | headerLength,
|  | const byte * | ciphertext,
|  | size_t | ciphertextLength
| ) |  |
| virtual

Decrypts and verifies a MAC in one call.

Parameters

  message | the decryption buffer
  mac | the mac buffer
  macSize | the size of the MAC buffer, in bytes
  iv | the iv buffer
  ivLength | the size of the IV buffer, in bytes
  header | the AAD buffer
  headerLength | the size of the AAD buffer, in bytes
  ciphertext | the ciphertext buffer
  ciphertextLength | the size of the ciphertext buffer, in bytes

Returns
  true if the MAC is valid and the decoding succeeded, false otherwise

DecryptAndVerify() decrypts and verifies the MAC in one call. `message` is a decryption buffer and should be at least as large as the ciphertext buffer.

The function returns true iff MAC is valid. DecryptAndVerify() assumes the MAC is truncated if `macLength < TagSize()`.

Reimplemented in XChaCha20Poly1305_Base, and ChaCha20Poly1305_Base.

## ◆ AlgorithmName()

virtual std::string AuthenticatedSymmetricCipher::AlgorithmName | ( |  | ) | const
| virtual

Provides the name of this algorithm.

Returns
  the standard algorithm name

The standard algorithm name can be a name like AES or AES/GCM. Some algorithms do not have standard names yet. For example, there is no standard algorithm name for Shoup's ECIES.

Reimplemented from Algorithm.

Reimplemented in XChaCha20Poly1305_Base, ChaCha20Poly1305_Base, GCM_Base, CCM_Base, and EAX_Base.

The documentation for this class was generated from the following file:

- cryptlib.h