Implments the SRTP encryption modes as defined in RFC3711. More...

#include <SrtpSymCrypto.h>

Collaboration diagram for SrtpSymCrypto:

Public Member Functions
	SrtpSymCrypto (int algo=SrtpEncryptionAESCM)

	SrtpSymCrypto (uint8_t *key, int32_t key_length, int algo=SrtpEncryptionAESCM)
	Constructor that initializes key data. More...

	~SrtpSymCrypto ()

void	encrypt (const uint8_t input, uint8_t output)
	Encrypts the inpout to the output. More...

bool	setNewKey (const uint8_t *key, int32_t keyLength)
	Set new key. More...

void	get_ctr_cipher_stream (uint8_t output, uint32_t length, uint8_t iv)
	Computes the cipher stream for AES CM mode. More...

void	ctr_encrypt (const uint8_t input, uint32_t inputLen, uint8_t output, uint8_t *iv)
	Counter-mode encryption. More...

void	ctr_encrypt (uint8_t data, uint32_t data_length, uint8_t iv)
	Counter-mode encryption, in place. More...

void	f8_deriveForIV (SrtpSymCrypto f8Cipher, uint8_t key, int32_t keyLen, uint8_t *salt, int32_t saltLen)
	Derive a AES context to compute the IV'. More...

void	f8_encrypt (const uint8_t data, uint32_t dataLen, uint8_t iv, SrtpSymCrypto *f8Cipher)
	AES F8 mode encryption, in place. More...

void	f8_encrypt (const uint8_t data, uint32_t dataLen, uint8_t out, uint8_t iv, SrtpSymCrypto f8Cipher)
	AES F8 mode encryption. More...

Private Member Functions
int	processBlock (F8_CIPHER_CTX f8ctx, const uint8_t in, int32_t length, uint8_t *out)

Private Attributes
void *	key

int32_t	algorithm

Detailed Description

Implments the SRTP encryption modes as defined in RFC3711.

The SRTP specification defines two encryption modes, AES-CTR (AES Counter mode) and AES-F8 mode. The AES-CTR is required, AES-F8 is optional.

Both modes are desinged to encrypt/decrypt data of arbitrary length (with a specified upper limit, refer to RFC 3711). These modes do not require that the amount of data to encrypt is a multiple of the AES blocksize (16 bytes), no padding is necessary.

The implementation uses the openSSL library as its cryptographic backend.

Author: Erik Eliasson elias.nosp@m.son@.nosp@m.it.kt.nosp@m.h.se; Johan Bilien jobi@.nosp@m.via..nosp@m.ecp.f.nosp@m.r; Werner Dittmann Werne.nosp@m.r.Di.nosp@m.ttman.nosp@m.n@t-.nosp@m.onlin.nosp@m.e.de

Definition at line 77 of file SrtpSymCrypto.h.

Constructor & Destructor Documentation

SrtpSymCrypto::SrtpSymCrypto ( int algo = SrtpEncryptionAESCM )

Definition at line 49 of file gcryptSrtpSymCrypto.cpp.

SrtpSymCrypto::SrtpSymCrypto	(	uint8_t *	key,
		int32_t	key_length,
		int	algo = `SrtpEncryptionAESCM`
	)

Constructor that initializes key data.

Parameters

key	Pointer to key bytes.
key_length	Number of key bytes.

Definition at line 53 of file gcryptSrtpSymCrypto.cpp.

SrtpSymCrypto::~SrtpSymCrypto ( )

Definition at line 60 of file gcryptSrtpSymCrypto.cpp.

Member Function Documentation

void SrtpSymCrypto::ctr_encrypt	(	const uint8_t *	input,
		uint32_t	inputLen,
		uint8_t *	output,
		uint8_t *	iv
	)

Counter-mode encryption.

This method performs the AES CM encryption.

Parameters

input	Pointer to input buffer, must be `inputLen` bytes.
inputLen	Number of bytes to process.
output	Pointer to output buffer, must be `inputLen` bytes.
iv	The initialization vector as input to create the cipher stream. Refer to chapter 4.1.1 in RFC 3711.

Definition at line 151 of file gcryptSrtpSymCrypto.cpp.

void SrtpSymCrypto::ctr_encrypt	(	uint8_t *	data,
		uint32_t	data_length,
		uint8_t *	iv
	)

Counter-mode encryption, in place.

This method performs the AES CM encryption.

Parameters

data	Pointer to input and output block, must be `dataLen` bytes.
data_length	Number of bytes to process.
iv	The initialization vector as input to create the cipher stream. Refer to chapter 4.1.1 in RFC 3711.

Definition at line 184 of file gcryptSrtpSymCrypto.cpp.

void SrtpSymCrypto::encrypt	(	const uint8_t *	input,
		uint8_t *	output
	)

Encrypts the inpout to the output.

Encrypts one input block to one output block. Each block is 16 bytes according to the AES encryption algorithm used.

Parameters

input	Pointer to input block, must be 16 bytes
output	Pointer to output block, must be 16 bytes

Definition at line 117 of file gcryptSrtpSymCrypto.cpp.

void SrtpSymCrypto::f8_deriveForIV	(	SrtpSymCrypto *	f8Cipher,
		uint8_t *	key,
		int32_t	keyLen,
		uint8_t *	salt,
		int32_t	saltLen
	)

Derive a AES context to compute the IV'.

See chapter 4.1.2.1 in RFC 3711.

Parameters

f8Cipher	Pointer to the AES context that will be used to encrypt IV to IV'
key	The master key
keyLen	Length of the master key.
salt	Master salt.
saltLen	length of master salt.

Definition at line 224 of file gcryptSrtpSymCrypto.cpp.

void SrtpSymCrypto::f8_encrypt	(	const uint8_t *	data,
		uint32_t	dataLen,
		uint8_t *	iv,
		SrtpSymCrypto *	f8Cipher
	)

AES F8 mode encryption, in place.

This method performs the AES F8 encryption, see chapter 4.1.2 in RFC 3711.

Parameters

data	Pointer to input and output block, must be `dataLen` bytes.
dataLen	Number of bytes to process.
iv	The initialization vector as input to create the cipher stream. Refer to chapter 4.1.1 in RFC 3711.
f8Cipher	An AES cipher context used to encrypt IV to IV'.

Definition at line 217 of file gcryptSrtpSymCrypto.cpp.

void SrtpSymCrypto::f8_encrypt	(	const uint8_t *	data,
		uint32_t	dataLen,
		uint8_t *	out,
		uint8_t *	iv,
		SrtpSymCrypto *	f8Cipher
	)

AES F8 mode encryption.

This method performs the AES F8 encryption, see chapter 4.1.2 in RFC 3711.

Parameters

data	Pointer to input and output block, must be `dataLen` bytes.
dataLen	Number of bytes to process.
out	Pointer to output buffer, must be `dataLen` bytes.
iv	The initialization vector as input to create the cipher stream. Refer to chapter 4.1.1 in RFC 3711.
f8Cipher	An AES cipher context used to encrypt IV to IV'.

Definition at line 260 of file gcryptSrtpSymCrypto.cpp.

void SrtpSymCrypto::get_ctr_cipher_stream	(	uint8_t *	output,
		uint32_t	length,
		uint8_t *	iv
	)

Computes the cipher stream for AES CM mode.

Parameters

output	Pointer to a buffer that receives the cipher stream. Must be at least `length` bytes long.
length	Number of cipher stream bytes to produce. Usually the same length as the data to be encrypted.
iv	The initialization vector as input to create the cipher stream. Refer to chapter 4.1.1 in RFC 3711.

Definition at line 128 of file gcryptSrtpSymCrypto.cpp.

int SrtpSymCrypto::processBlock	(	F8_CIPHER_CTX *	f8ctx,
		const uint8_t *	in,
		int32_t	length,
		uint8_t *	out
	)

private

Definition at line 297 of file gcryptSrtpSymCrypto.cpp.

bool SrtpSymCrypto::setNewKey	(	const uint8_t *	key,
		int32_t	keyLength
	)

Set new key.

Parameters

key	Pointer to key data, must have at least a size of keyLength
keyLength	Length of the key in bytes, must be 16, 24, or 32

Returns: false if key could not set.

Definition at line 74 of file gcryptSrtpSymCrypto.cpp.

Field Documentation

int32_t SrtpSymCrypto::algorithm

private

Definition at line 248 of file SrtpSymCrypto.h.

void* SrtpSymCrypto::key

private

Definition at line 247 of file SrtpSymCrypto.h.

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

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Field Documentation