ocb.h File Reference

Offset Codebook (OCB3) AEAD mode as specified in RFC 7253. More...

Detailed Description

Offset Codebook (OCB3) AEAD mode as specified in RFC 7253.

NOTE: The OCB algorithm is covered by patents in the USA owned by Phillip Rogaway. A free licence is granted for any open-source or non-military project. Check http://web.cs.ucdavis.edu/~rogaway/ocb/grant.htm for details.

Author

Mathias Tausig mathi.nosp@m.as@t.nosp@m.ausig.nosp@m..at

Definition in file ocb.h.

#include "crypto/ciphers.h"
#include <stdint.h>
#include <stddef.h>

Include dependency graph for ocb.h:

Go to the source code of this file.

Functions
int32_t	cipher_encrypt_ocb (const cipher_t *cipher, const uint8_t *auth_data, size_t auth_data_len, uint8_t tag_len, const uint8_t *nonce, size_t nonce_len, const uint8_t *input, size_t input_len, uint8_t *output)
	Encrypt and authenticate data of arbitrary length in OCB mode. More...
int32_t	cipher_decrypt_ocb (const cipher_t *cipher, const uint8_t *auth_data, size_t auth_data_len, uint8_t tag_len, const uint8_t *nonce, size_t nonce_len, const uint8_t *input, size_t input_len, uint8_t *output)
	Decrypt and verify the authentication of OCB encrypted data. More...

OCB error codes
#define	OCB_ERR_INVALID_NONCE_LENGTH   (-2)
	Returned if a nonce of bad length (empty or more than 15 bytes) was used.
#define	OCB_ERR_INVALID_BLOCK_LENGTH   (-3)
	OCB only works with ciphers with a block size of 128 bit.
#define	OCB_ERR_INVALID_DATA_LENGTH   (-3)
	Returned if the amount of input data cannot be handled by this implementation.
#define	OCB_ERR_INVALID_TAG_LENGTH   (-4)
	Returned if a tag of bad length was requested (empty or more than 16 bytes)
#define	OCB_ERR_INVALID_TAG   (-5)
	Returned if the authentication failed during decryption.

Function Documentation

cipher_decrypt_ocb()

int32_t cipher_decrypt_ocb	(	const cipher_t *	cipher,
		const uint8_t *	auth_data,
		size_t	auth_data_len,
		uint8_t	tag_len,
		const uint8_t *	nonce,
		size_t	nonce_len,
		const uint8_t *	input,
		size_t	input_len,
		uint8_t *	output
	)

Decrypt and verify the authentication of OCB encrypted data.

Parameters

cipher	Already initialized cipher struct
auth_data	Additional data to authenticate in MAC
auth_data_len	Length of additional data
tag_len	Length of the appended tag (at least 1, at most 16 bytes)
nonce	Nonce for the encryption (must be unique)
nonce_len	Length of the nonce in bytes (at most 15)
input	pointer to the ciphertext with the tag appended
input_len	length of the input data. input_len - tag_len must be smaller than INT32_MAX (2^31-1)
output	pointer to allocated memory for the plaintext data. It has to be of size input_len - tag_len. Will contain only zeroes, if the authentication fails.

Returns

Length of the plaintext data or a (negative) error code

cipher_encrypt_ocb()

int32_t cipher_encrypt_ocb	(	const cipher_t *	cipher,
		const uint8_t *	auth_data,
		size_t	auth_data_len,
		uint8_t	tag_len,
		const uint8_t *	nonce,
		size_t	nonce_len,
		const uint8_t *	input,
		size_t	input_len,
		uint8_t *	output
	)

Encrypt and authenticate data of arbitrary length in OCB mode.

Parameters

cipher	Already initialized cipher struct
auth_data	Additional data to authenticate in MAC
auth_data_len	Length of additional data
tag_len	Length of the appended tag (at least 1, at most 16 bytes)
nonce	Nonce for the encryption (must be unique)
nonce_len	Length of the nonce in bytes (at most 15)
input	pointer to input data to encrypt
input_len	length of the input data. input_len + tag_len must be smaller than INT32_MAX (2^31-1)
output	pointer to allocated memory for encrypted data. The tag will be appended to the ciphertext. It has to be of size data_len + tag_len.

Returns

Length of the encrypted data (including the tag) or a (negative) error code