tc_cbc_mode_decrypt() function

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

Syntax

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Summary

Declaration

Definition

from cbc_mode.h:143

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);

Implemented in cbc_mode.c:77

Arguments

Argument

Description

out

IN/OUT -- buffer to receive decrypted data

outlen

IN -- length of plaintext buffer in bytes

IN -- ciphertext to decrypt, including IV

inlen

IN -- length of ciphertext buffer in bytes

IN -- the IV for the this encrypt/decrypt

sched

IN -- AES key schedule for this decrypt

Return value

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

Notes

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