ctr.h File Reference

Counter mode of operation for block ciphers. More...

Detailed Description

Counter mode of operation for block ciphers.

Author

Freie Universitaet Berlin, Computer Systems & Telematics

Nico von Geyso nico..nosp@m.geys.nosp@m.o@fu-.nosp@m.berl.nosp@m.in.de

Definition in file ctr.h.

#include "crypto/ciphers.h"

Include dependency graph for ctr.h:

Go to the source code of this file.

int	cipher_encrypt_ctr (const cipher_t *cipher, uint8_t nonce_counter[16], uint8_t nonce_len, const uint8_t *input, size_t length, uint8_t *output)
	Encrypt data of arbitrary length in counter mode.
int	cipher_decrypt_ctr (const cipher_t *cipher, uint8_t nonce_counter[16], uint8_t nonce_len, const uint8_t *input, size_t length, uint8_t *output)
	Decrypt data of arbitrary length in counter mode.

Function Documentation

cipher_decrypt_ctr()

int cipher_decrypt_ctr	(	const cipher_t *	cipher,
		uint8_t	nonce_counter[16],
		uint8_t	nonce_len,
		const uint8_t *	input,
		size_t	length,
		uint8_t *	output
	)

Decrypt data of arbitrary length in counter mode.

Encryption and decryption in ctr mode are basically the same.

Parameters

cipher	Already initialized cipher struct
nonce_counter	A nounce and a counter encoded in 16 octets. The counter will be modified in each block encryption.
nonce_len	Length of the nonce in octets. As nounce and counter have to fit in one aligned 16 octet block, maximum length of nonce is limited by input_len: 16 - log_2(input_len)
input	pointer to input data to encrypt
length	length of the input data
output	pointer to allocated memory for encrypted data. It has to be of size data_len.

Returns

Length of decrypted data on a successful decryption

A negative error code if something went wrong

cipher_encrypt_ctr()

int cipher_encrypt_ctr	(	const cipher_t *	cipher,
		uint8_t	nonce_counter[16],
		uint8_t	nonce_len,
		const uint8_t *	input,
		size_t	length,
		uint8_t *	output
	)

Encrypt data of arbitrary length in counter mode.

Parameters

cipher	Already initialized cipher struct
nonce_counter	A nounce and a counter encoded in 16 octets. The counter will be modified in each block encryption.
nonce_len	Length of the nonce in octets. As nounce and counter have to fit in one aligned 16 octet block, maximum length of nonce is limited by input_len: 16 - log_2(input_len)
input	pointer to input data to encrypt
length	length of the input data
output	pointer to allocated memory for encrypted data. It has to be of size data_len.

Returns

Length of encrypted data on a successful encryption

A negative error code if something went wrong