Hi,
Could someone explain what the masks CRYPTO_TFM_REQ_MASK and
CRYPTO_TFM_RES_MASK do and why they must be manipulated before and after
crypto_cipher_setkey(...)?
Here is an example use (from crypto_pcbc_setkey):
crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
err = crypto_cipher_setkey(child, key, keylen);
crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
It would be very useful if someone added some comments to these
definitions (found in linux/crypto.h):
/*
* Transform masks and values (for crt_flags).
*/
#define CRYPTO_TFM_REQ_MASK 0x000fff00
#define CRYPTO_TFM_RES_MASK 0xfff00000
#define CRYPTO_TFM_REQ_WEAK_KEY 0x00000100
#define CRYPTO_TFM_REQ_MAY_SLEEP 0x00000200
#define CRYPTO_TFM_REQ_MAY_BACKLOG 0x00000400
#define CRYPTO_TFM_RES_WEAK_KEY 0x00100000
#define CRYPTO_TFM_RES_BAD_KEY_LEN 0x00200000
#define CRYPTO_TFM_RES_BAD_KEY_SCHED 0x00400000
#define CRYPTO_TFM_RES_BAD_BLOCK_LEN 0x00800000
#define CRYPTO_TFM_RES_BAD_FLAGS 0x01000000
Thanks,
Dimitris
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