From 355912852115cd8aa4ad02c25182ae615ce925fb Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Tue, 14 Jun 2016 07:34:13 +0200 Subject: crypto: drbg - use CTR AES instead of ECB AES The CTR DRBG derives its random data from the CTR that is encrypted with AES. This patch now changes the CTR DRBG implementation such that the CTR AES mode is employed. This allows the use of steamlined CTR AES implementation such as ctr-aes-aesni. Unfortunately there are the following subtile changes we need to apply when using the CTR AES mode: - the CTR mode increments the counter after the cipher operation, but the CTR DRBG requires the increment before the cipher op. Hence, the crypto_inc is applied to the counter (drbg->V) once it is recalculated. - the CTR mode wants to encrypt data, but the CTR DRBG is interested in the encrypted counter only. The full CTR mode is the XOR of the encrypted counter with the plaintext data. To access the encrypted counter, the patch uses a NULL data vector as plaintext to be "encrypted". Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- include/crypto/drbg.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/crypto') diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h index d961b2b..b2fe15d 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -43,6 +43,7 @@ #include #include #include +#include #include #include #include @@ -115,6 +116,14 @@ struct drbg_state { /* some memory the DRBG can use for its operation */ unsigned char *scratchpad; void *priv_data; /* Cipher handle */ + + struct crypto_skcipher *ctr_handle; /* CTR mode cipher handle */ + struct skcipher_request *ctr_req; /* CTR mode request handle */ + __u8 *ctr_null_value_buf; /* CTR mode unaligned buffer */ + __u8 *ctr_null_value; /* CTR mode aligned zero buf */ + struct completion ctr_completion; /* CTR mode async handler */ + int ctr_async_err; /* CTR mode async error */ + bool seeded; /* DRBG fully seeded? */ bool pr; /* Prediction resistance enabled? */ struct work_struct seed_work; /* asynchronous seeding support */ -- cgit v1.1