# AuthenticatedSymmetricCipher Class Reference

`#include <cryptlib.h>`

Inheritance diagram for AuthenticatedSymmetricCipher:

List of all members.

## Detailed Description

interface for 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/decrypt the data, and the MessageAuthenticationCode part of this interface is used to input additional authenticated data (AAD, which is MAC'ed but not encrypted), and to generate/verify the MAC.

Definition at line 638 of file cryptlib.h.

## Public Types
enum | IV_Requirement { UNIQUE_IV = 0, RANDOM_IV, UNPREDICTABLE_RANDOM_IV, INTERNALLY_GENERATED_IV, NOT_RESYNCHRONIZABLE }
## Public Member Functions
virtual lword | MaxHeaderLength () const =0
| the maximum length of AAD that can be input before the encrypted data
virtual lword | MaxMessageLength () const =0
| the maximum length of encrypted data
virtual lword | MaxFooterLength () const
| the maximum length of AAD that can be input after the encrypted data
virtual bool | NeedsPrespecifiedDataLengths () const
| if this function returns true, SpecifyDataLengths() must be called before attempting to input data
void | SpecifyDataLengths (lword headerLength, lword messageLength, lword footerLength=0)
| this function only needs to be called if NeedsPrespecifiedDataLengths() returns true
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)
| encrypt and generate MAC in one call. will truncate MAC if macSize < TagSize()
virtual bool | DecryptAndVerify (byte *message, const byte *mac, size_t macLength, const byte *iv, int ivLength, const byte *header, size_t headerLength, const byte *ciphertext, size_t ciphertextLength)
| decrypt and verify MAC in one call, returning true iff MAC is valid. will assume MAC is truncated if macLength < TagSize()
virtual std::string | AlgorithmName () const =0
| returns name of this algorithm, not universally implemented yet
virtual size_t | MinKeyLength () const =0
| returns smallest valid key length in bytes */
virtual size_t | MaxKeyLength () const =0
| returns largest valid key length in bytes */
virtual size_t | DefaultKeyLength () const =0
| returns default (recommended) key length in bytes */
virtual size_t | GetValidKeyLength (size_t n) const =0
| returns the smallest valid key length in bytes that is >= min(n, GetMaxKeyLength())
virtual bool | IsValidKeyLength (size_t n) const
| returns whether n is a valid key length
virtual void | SetKey (const byte *key, size_t length, const NameValuePairs &params=g_nullNameValuePairs)
| set or reset the key of this object
void | SetKeyWithRounds (const byte *key, size_t length, int rounds)
| calls SetKey() with an NameValuePairs object that just specifies "Rounds"
void | SetKeyWithIV (const byte *key, size_t length, const byte *iv, size_t ivLength)
| calls SetKey() with an NameValuePairs object that just specifies "IV"
void | SetKeyWithIV (const byte *key, size_t length, const byte *iv)
| calls SetKey() with an NameValuePairs object that just specifies "IV"
virtual IV_Requirement | IVRequirement () const =0
| returns the minimal requirement for secure IVs
bool | IsResynchronizable () const
| returns whether this object can be resynchronized (i.e. supports initialization vectors)
bool | CanUseRandomIVs () const
| returns whether this object can use random IVs (in addition to ones returned by GetNextIV)
bool | CanUsePredictableIVs () const
| returns whether this object can use random but possibly predictable IVs (in addition to ones returned by GetNextIV)
bool | CanUseStructuredIVs () const
| returns whether this object can use structured IVs, for example a counter (in addition to ones returned by GetNextIV)
virtual unsigned int | IVSize () const
unsigned int | DefaultIVLength () const
| returns default length of IVs accepted by this object
virtual unsigned int | MinIVLength () const
| returns minimal length of IVs accepted by this object
virtual unsigned int | MaxIVLength () const
| returns maximal length of IVs accepted by this object
virtual void | Resynchronize (const byte *iv, int ivLength=-1)
| resynchronize with an IV. ivLength=-1 means use IVSize()
virtual void | GetNextIV (RandomNumberGenerator &rng, byte *IV)
| get a secure IV for the next message
HashTransformation & | Ref ()
| return a reference to this object,
virtual void | Update (const byte *input, size_t length)=0
| process more input
virtual byte * | CreateUpdateSpace (size_t &size)
| request space to write input into
virtual void | Final (byte *digest)
| compute hash for current message, then restart for a new message
virtual void | Restart ()
| discard the current state, and restart with a new message
virtual unsigned int | DigestSize () const =0
| size of the hash/digest/MAC returned by Final()
unsigned int | TagSize () const
| same as DigestSize()
virtual unsigned int | BlockSize () const
| block size of underlying compression function, or 0 if not block based
virtual unsigned int | OptimalBlockSize () const
| input to Update() should have length a multiple of this for optimal speed
virtual unsigned int | OptimalDataAlignment () const
| returns how input should be aligned for optimal performance
virtual void | CalculateDigest (byte *digest, const byte *input, size_t length)
| use this if your input is in one piece and you don't want to call Update() and Final() separately
virtual bool | Verify (const byte *digest)
| verify that digest is a valid digest for the current message, then reinitialize the object
virtual bool | VerifyDigest (const byte *digest, const byte *input, size_t length)
| use this if your input is in one piece and you don't want to call Update() and Verify() separately
virtual void | TruncatedFinal (byte *digest, size_t digestSize)=0
| truncated version of Final()
virtual void | CalculateTruncatedDigest (byte *digest, size_t digestSize, const byte *input, size_t length)
| truncated version of CalculateDigest()
virtual bool | TruncatedVerify (const byte *digest, size_t digestLength)
| truncated version of Verify()
virtual bool | VerifyTruncatedDigest (const byte *digest, size_t digestLength, const byte *input, size_t length)
| truncated version of VerifyDigest()
virtual Clonable * | Clone () const
| this is not implemented by most classes yet
StreamTransformation & | Ref ()
| return a reference to this object,
virtual unsigned int | MandatoryBlockSize () const
| returns block size, if input must be processed in blocks, otherwise 1
virtual unsigned int | OptimalBlockSize () const
| returns the input block size that is most efficient for this cipher
virtual unsigned int | GetOptimalBlockSizeUsed () const
| returns how much of the current block is used up
virtual unsigned int | OptimalDataAlignment () const
| returns how input should be aligned for optimal performance
virtual void | ProcessData (byte *outString, const byte *inString, size_t length)=0
| encrypt or decrypt an array of bytes of specified length
virtual void | ProcessLastBlock (byte *outString, const byte *inString, size_t length)
| for ciphers where the last block of data is special, encrypt or decrypt the last block of data
virtual unsigned int | MinLastBlockSize () const
| returns the minimum size of the last block, 0 indicating the last block is not special
void | ProcessString (byte *inoutString, size_t length)
| same as ProcessData(inoutString, inoutString, length)
void | ProcessString (byte *outString, const byte *inString, size_t length)
| same as ProcessData(outString, inString, length)
byte | ProcessByte (byte input)
| implemented as {ProcessData(&input, &input, 1); return input;}
virtual bool | IsRandomAccess () const =0
| returns whether this cipher supports random access
virtual void | Seek (lword n)
| for random access ciphers, seek to an absolute position
virtual bool | IsSelfInverting () const =0
| returns whether this transformation is self-inverting (e.g. xor with a keystream)
virtual bool | IsForwardTransformation () const =0
| returns whether this is an encryption object
## Protected Member Functions
const Algorithm & | GetAlgorithm () const
virtual void | UncheckedSpecifyDataLengths (lword headerLength, lword messageLength, lword footerLength)
virtual void | UncheckedSetKey (const byte *key, unsigned int length, const NameValuePairs &params)=0
void | ThrowIfInvalidKeyLength (size_t length)
void | ThrowIfResynchronizable ()
void | ThrowIfInvalidIV (const byte *iv)
size_t | ThrowIfInvalidIVLength (int size)
const byte * | GetIVAndThrowIfInvalid (const NameValuePairs &params, size_t &size)
void | AssertValidKeyLength (size_t length) const
void | ThrowIfInvalidTruncatedSize (size_t size) const
## Classes
class | BadState
| this indicates that a member function was called in the wrong state, for example trying to encrypt a message before having set the key or IV More...

## Member Function Documentation

virtual bool AuthenticatedSymmetricCipher::NeedsPrespecifiedDataLengths | ( |  | ) | const`[inline, virtual]`

if this function returns true, SpecifyDataLengths() must be called before attempting to input data

This is the case for some schemes, such as CCM.

Reimplemented in CCM_Base.

Definition at line 657 of file cryptlib.h.

void SimpleKeyingInterface::SetKey | ( | const byte * | key,
|  | size_t | length,
|  | const NameValuePairs & | params = `g_nullNameValuePairs` |
| ) |  |  | `[virtual, inherited]`

set or reset the key of this object

Parameters:

  | params | is used to specify Rounds, BlockSize, etc.

Reimplemented in AuthenticatedSymmetricCipherBase.

Definition at line 53 of file cryptlib.cpp.

Referenced by SimpleKeyingInterface::SetKeyWithIV(), and SimpleKeyingInterface::SetKeyWithRounds().

bool SimpleKeyingInterface::IsResynchronizable | ( |  | ) | const`[inline, inherited]`

returns whether this object can be resynchronized (i.e. supports initialization vectors)

If this function returns true, and no IV is passed to SetKey() and CanUseStructuredIVs()==true, an IV of all 0's will be assumed.

Definition at line 393 of file cryptlib.h.

void SimpleKeyingInterface::GetNextIV | ( | RandomNumberGenerator & | rng,
|  | byte * | IV |
| ) |  |  | `[virtual, inherited]`

get a secure IV for the next message

This method should be called after you finish encrypting one message and are ready to start the next one. After calling it, you must call SetKey() or Resynchronize() before using this object again. This method is not implemented on decryption objects.

Definition at line 129 of file cryptlib.cpp.

References RandomNumberGenerator::GenerateBlock().

HashTransformation& HashTransformation::Ref | ( |  | ) | `[inline, inherited]`

return a reference to this object,

This function is useful for passing a temporary HashTransformation object to a function that takes a non-const reference.

Definition at line 546 of file cryptlib.h.

virtual void HashTransformation::Final | ( | byte * | digest | ) | `[inline, virtual, inherited]`

compute hash for current message, then restart for a new message

Precondition:
  size of digest == DigestSize().

Definition at line 556 of file cryptlib.h.

Referenced by PKCS5_PBKDF2_HMAC< T >::DeriveKey(), RandomPool::IncorporateEntropy(), and HMAC_Base::TruncatedFinal().

virtual bool HashTransformation::Verify | ( | const byte * | digest | ) | `[inline, virtual, inherited]`

verify that digest is a valid digest for the current message, then reinitialize the object

Default implementation is to call Final() and do a bitwise comparison between its output and digest.

Definition at line 586 of file cryptlib.h.

StreamTransformation& StreamTransformation::Ref | ( |  | ) | `[inline, inherited]`

return a reference to this object,

This function is useful for passing a temporary StreamTransformation object to a function that takes a non-const reference.

Definition at line 483 of file cryptlib.h.

virtual unsigned int StreamTransformation::OptimalBlockSize | ( |  | ) | const`[inline, virtual, inherited]`

returns the input block size that is most efficient for this cipher

Note:
  optimal input length is n * OptimalBlockSize() - GetOptimalBlockSizeUsed() for any n > 0

Definition at line 490 of file cryptlib.h.

virtual void StreamTransformation::ProcessData | ( | byte * | outString,
|  | const byte * | inString,
|  | size_t | length |
| ) |  |  | `[pure virtual, inherited]`

encrypt or decrypt an array of bytes of specified length

Note:
  either inString == outString, or they don't overlap

Implemented in Weak1::ARC4_Base, AuthenticatedSymmetricCipherBase, and PublicBlumBlumShub.

Referenced by AuthenticatedSymmetricCipherBase::ProcessData(), and StreamTransformation::ProcessLastBlock().

void StreamTransformation::ProcessLastBlock | ( | byte * | outString,
|  | const byte * | inString,
|  | size_t | length |
| ) |  |  | `[virtual, inherited]`

for ciphers where the last block of data is special, encrypt or decrypt the last block of data

For now the only use of this function is for CBC-CTS mode.

Definition at line 187 of file cryptlib.cpp.

References Algorithm::AlgorithmName(), StreamTransformation::MandatoryBlockSize(), StreamTransformation::MinLastBlockSize(), and StreamTransformation::ProcessData().

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

- cryptlib.h
- cryptlib.cpp