strciphr.h File Reference

Classes for implementing stream ciphers. More...

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Classes
class	AbstractPolicyHolder< POLICY_INTERFACE, BASE >
	Access a stream cipher policy object. More...
class	ConcretePolicyHolder< POLICY, BASE, POLICY_INTERFACE >
	Stream cipher policy object. More...
struct	AdditiveCipherAbstractPolicy
	Policy object for additive stream ciphers. More...
struct	AdditiveCipherConcretePolicy< WT, W, X, BASE >
	Base class for additive stream ciphers. More...
class	AdditiveCipherTemplate< BASE >
	Base class for additive stream ciphers with SymmetricCipher interface. More...
class	CFB_CipherAbstractPolicy
	Policy object for feeback based stream ciphers. More...
struct	CFB_CipherConcretePolicy< WT, W, BASE >
	Base class for feedback based stream ciphers. More...
struct	CFB_CipherConcretePolicy< WT, W, BASE >::RegisterOutput< B >
	Provides alternate access to a feedback register. More...
class	CFB_CipherTemplate< BASE >
	Base class for feedback based stream ciphers with SymmetricCipher interface. More...
class	CFB_EncryptionTemplate< BASE >
	Base class for feedback based stream ciphers in the forward direction with SymmetricCipher interface. More...
class	CFB_DecryptionTemplate< BASE >
	Base class for feedback based stream ciphers in the reverse direction with SymmetricCipher interface. More...
class	CFB_RequireFullDataBlocks< BASE >
	Base class for feedback based stream ciphers with a mandatory block size. More...
class	SymmetricCipherFinal< BASE, INFO >
	SymmetricCipher implementation. More...

Macros
#define	CRYPTOPP_KEYSTREAM_OUTPUT_WORD(x, b, i, a)   PutWord(bool(x & OUTPUT_ALIGNED), b, output+i*sizeof(WordType), (x & INPUT_NULL) ? (a) : (a) ^ GetWord<WordType>(bool(x & INPUT_ALIGNED), b, input+i*sizeof(WordType)));
	Helper macro to implement OperateKeystream. More...
#define	CRYPTOPP_KEYSTREAM_OUTPUT_XMM(x, i, a)
	Helper macro to implement OperateKeystream. More...
#define	CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH(x, y)
	Helper macro to implement OperateKeystream. More...

Enumerations
enum	KeystreamOperationFlags { OUTPUT_ALIGNED =1, INPUT_ALIGNED =2, INPUT_NULL = 4 }
	Keystream operation flags. More...
enum	KeystreamOperation {   WRITE_KEYSTREAM = INPUT_NULL, WRITE_KEYSTREAM_ALIGNED = INPUT_NULL | OUTPUT_ALIGNED, XOR_KEYSTREAM = 0, XOR_KEYSTREAM_INPUT_ALIGNED = INPUT_ALIGNED,   XOR_KEYSTREAM_OUTPUT_ALIGNED = OUTPUT_ALIGNED, XOR_KEYSTREAM_BOTH_ALIGNED = OUTPUT_ALIGNED | INPUT_ALIGNED }
	Keystream operation flags. More...

Detailed Description

Classes for implementing stream ciphers.

This file contains helper classes for implementing stream ciphers. All this infrastructure may look very complex compared to what's in Crypto++ 4.x, but stream ciphers implementations now support a lot of new functionality, including better performance (minimizing copying), resetting of keys and IVs, and methods to query which features are supported by a cipher.

Here's an explanation of these classes. The word "policy" is used here to mean a class with a set of methods that must be implemented by individual stream cipher implementations. This is usually much simpler than the full stream cipher API, which is implemented by either AdditiveCipherTemplate or CFB_CipherTemplate using the policy. So for example, an implementation of SEAL only needs to implement the AdditiveCipherAbstractPolicy interface (since it's an additive cipher, i.e., it xors a keystream into the plaintext). See this line in seal.h:

    typedef SymmetricCipherFinal<ConcretePolicyHolder<SEAL_Policy<B>, AdditiveCipherTemplate<> > > Encryption;

AdditiveCipherTemplate and CFB_CipherTemplate are designed so that they don't need to take a policy class as a template parameter (although this is allowed), so that their code is not duplicated for each new cipher. Instead they each get a reference to an abstract policy interface by calling AccessPolicy() on itself, so AccessPolicy() must be overridden to return the actual policy reference. This is done by the ConceretePolicyHolder class. Finally, SymmetricCipherFinal implements the constructors and other functions that must be implemented by the most derived class.

Definition in file strciphr.h.

Macro Definition Documentation

CRYPTOPP_KEYSTREAM_OUTPUT_WORD

#define CRYPTOPP_KEYSTREAM_OUTPUT_WORD	(		x,
			b,
			i,
			a
	)		PutWord(bool(x & OUTPUT_ALIGNED), b, output+i*sizeof(WordType), (x & INPUT_NULL) ? (a) : (a) ^ GetWord<WordType>(bool(x & INPUT_ALIGNED), b, input+i*sizeof(WordType)));

Helper macro to implement OperateKeystream.

Parameters

x	KeystreamOperation mask
b	Endian order
i	index in output buffer
a	value to output

Definition at line 255 of file strciphr.h.

CRYPTOPP_KEYSTREAM_OUTPUT_XMM

#define CRYPTOPP_KEYSTREAM_OUTPUT_XMM	(		x,
			i,
			a
	)

Value:

{\
    __m128i t = (x & INPUT_NULL) ? a : _mm_xor_si128(a, (x & INPUT_ALIGNED) ? _mm_load_si128((__m128i *)input+i) : _mm_loadu_si128((__m128i *)input+i));\
    if (x & OUTPUT_ALIGNED) _mm_store_si128((__m128i *)output+i, t);\
    else _mm_storeu_si128((__m128i *)output+i, t);}

Helper macro to implement OperateKeystream.

Parameters

x	KeystreamOperation mask
i	index in output buffer
a	value to output

Definition at line 262 of file strciphr.h.

CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH

#define CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH	(		x,
			y
	)

Value:

switch (operation)                          \
    {                                           \
        case WRITE_KEYSTREAM:                   \
            x(WRITE_KEYSTREAM)                  \
            break;                              \
        case XOR_KEYSTREAM:                     \
            x(XOR_KEYSTREAM)                    \
            input += y;                         \
            break;                              \
        case XOR_KEYSTREAM_INPUT_ALIGNED:       \
            x(XOR_KEYSTREAM_INPUT_ALIGNED)      \
            input += y;                         \
            break;                              \
        case XOR_KEYSTREAM_OUTPUT_ALIGNED:      \
            x(XOR_KEYSTREAM_OUTPUT_ALIGNED)     \
            input += y;                         \
            break;                              \
        case WRITE_KEYSTREAM_ALIGNED:           \
            x(WRITE_KEYSTREAM_ALIGNED)          \
            break;                              \
        case XOR_KEYSTREAM_BOTH_ALIGNED:        \
            x(XOR_KEYSTREAM_BOTH_ALIGNED)       \
            input += y;                         \
            break;                              \
    }                                           \
    output += y;

Helper macro to implement OperateKeystream.

Definition at line 268 of file strciphr.h.

Enumeration Type Documentation

KeystreamOperationFlags

enum KeystreamOperationFlags

Keystream operation flags.

See also

AdditiveCipherAbstractPolicy::GetBytesPerIteration(), AdditiveCipherAbstractPolicy::GetOptimalBlockSize() and AdditiveCipherAbstractPolicy::GetAlignment()

Enumerator
OUTPUT_ALIGNED	Output buffer is aligned.
INPUT_ALIGNED	Input buffer is aligned.
INPUT_NULL	Input buffer is NULL.

Definition at line 76 of file strciphr.h.

KeystreamOperation

enum KeystreamOperation

Keystream operation flags.

See also

AdditiveCipherAbstractPolicy::GetBytesPerIteration(), AdditiveCipherAbstractPolicy::GetOptimalBlockSize() and AdditiveCipherAbstractPolicy::GetAlignment()

Enumerator
WRITE_KEYSTREAM	Wirte the keystream to the output buffer, input is NULL.
WRITE_KEYSTREAM_ALIGNED	Wirte the keystream to the aligned output buffer, input is NULL.
XOR_KEYSTREAM	XOR the input buffer and keystream, write to the output buffer.
XOR_KEYSTREAM_INPUT_ALIGNED	XOR the aligned input buffer and keystream, write to the output buffer.
XOR_KEYSTREAM_OUTPUT_ALIGNED	XOR the input buffer and keystream, write to the aligned output buffer.
XOR_KEYSTREAM_BOTH_ALIGNED	XOR the aligned input buffer and keystream, write to the aligned output buffer.

Definition at line 88 of file strciphr.h.