Hello,
I have a question concerning the decryption of a 90 byte AES CTR ciphertext with a given 16 byte key and 12 byte IV (=8 byte nonce, 4 byte counter).
I've tried to set my variables (ct, key, iv) in the aes_ctr example. The problem is now that my 12 byte IV cannot be set using the function psa_cipher_set_iv.
Next, I've tried to generate a 12 byte IV and found out that the length is not accepted. However, according to the psa api specification, 12 byte is a valid length for an IV.
In more detail I get the following errors:
#define NRF_CRYPTO_EXAMPLE_AES_BLOCK_SIZE (12)
#define NRF_CRYPTO_EXAMPLE_AES_MAX_TEXT_SIZE (90)
/* AES IV buffer */
static uint8_t m_iv[NRF_CRYPTO_EXAMPLE_AES_BLOCK_SIZE];
status = psa_cipher_generate_iv(&operation, m_iv, sizeof(m_iv), &olen); // status is (Error: -138) => PSA_ERROR_BUFFER_TOO_SMALL
and
status = psa_cipher_set_iv(&operation, m_iv, /sizeof(m_iv)); // status is (Error: -135) => PSA_ERROR_INVALID_ARGUMENT
Could you please tell me how I can solve this problem and decrypt my ciphertext?
Thanks in advance.
Best regards
PS I'm working on the nrf9160 with SDK version 1.6.1.
