tc_cbc_mode.c File Reference

#include "tc_cbc_mode.h"
#include "tc_constants.h"
#include "tc_utils.h"

Functions
int	tc_cbc_mode_encrypt (uint8_t *out, unsigned int outlen, const uint8_t *in, unsigned int inlen, const uint8_t *iv, const TCAesKeySched_t sched)
	CBC encryption procedure CBC encrypts inlen bytes of the in buffer into the out buffer using the encryption key schedule provided, prepends iv to out. More...
int	tc_cbc_mode_decrypt (uint8_t *out, unsigned int outlen, const uint8_t *in, unsigned int inlen, const uint8_t *iv, const TCAesKeySched_t sched)
	CBC decryption procedure CBC decrypts inlen bytes of the in buffer into the out buffer using the provided encryption key schedule. More...

Function Documentation

tc_cbc_mode_decrypt()

int tc_cbc_mode_decrypt	(	uint8_t *	out,
		unsigned int	outlen,
		const uint8_t *	in,
		unsigned int	inlen,
		const uint8_t *	iv,
		const TCAesKeySched_t	sched
	)

CBC decryption procedure CBC decrypts inlen bytes of the in buffer into the out buffer using the provided encryption key schedule.

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: out == NULL or in == NULL or sched == NULL or inlen == 0 or outlen == 0 or (inlen % TC_AES_BLOCK_SIZE) != 0 or (outlen % TC_AES_BLOCK_SIZE) != 0 or outlen != inlen + TC_AES_BLOCK_SIZE

Note

Assumes:- in == iv + ciphertext, i.e. the iv and the ciphertext are contiguous. This allows for a very efficient decryption algorithm that would not otherwise be possible

• sched was configured by aes_set_decrypt_key
• out buffer is large enough to hold the decrypted plaintext and is a contiguous buffer
• inlen gives the number of bytes in the in buffer

Parameters

out	IN/OUT – buffer to receive decrypted data
outlen	IN – length of plaintext buffer in bytes
in	IN – ciphertext to decrypt, including IV
inlen	IN – length of ciphertext buffer in bytes
iv	IN – the IV for the this encrypt/decrypt
sched	IN – AES key schedule for this decrypt

tc_cbc_mode_encrypt()

int tc_cbc_mode_encrypt	(	uint8_t *	out,
		unsigned int	outlen,
		const uint8_t *	in,
		unsigned int	inlen,
		const uint8_t *	iv,
		const TCAesKeySched_t	sched
	)

CBC encryption procedure CBC encrypts inlen bytes of the in buffer into the out buffer using the encryption key schedule provided, prepends iv to out.

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: out == NULL or in == NULL or ctr == NULL or sched == NULL or inlen == 0 or (inlen % TC_AES_BLOCK_SIZE) != 0 or (outlen % TC_AES_BLOCK_SIZE) != 0 or outlen != inlen + TC_AES_BLOCK_SIZE

Note

Assumes: - sched has been configured by aes_set_encrypt_key

• iv contains a 16 byte random string
• out buffer is large enough to hold the ciphertext + iv
• out buffer is a contiguous buffer
• in holds the plaintext and is a contiguous buffer
• inlen gives the number of bytes in the in buffer

Parameters

out	IN/OUT – buffer to receive the ciphertext
outlen	IN – length of ciphertext buffer in bytes
in	IN – plaintext to encrypt
inlen	IN – length of plaintext buffer in bytes
iv	IN – the IV for the this encrypt/decrypt
sched	IN – AES key schedule for this encrypt