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authorStephan Mueller <smueller@chronox.de>2016-06-14 07:34:13 +0200
committerHerbert Xu <herbert@gondor.apana.org.au>2016-06-15 17:07:53 +0800
commit355912852115cd8aa4ad02c25182ae615ce925fb (patch)
treef25c7201d6538cebae6a4d5ded1998a2164717de /crypto/Kconfig
parente123be16120df6cdda4e1811a49326125f0aa4dd (diff)
downloadlinux-stericsson-355912852115cd8aa4ad02c25182ae615ce925fb.tar.gz
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 <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/Kconfig')
-rw-r--r--crypto/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 1d33beb6a1ae..c903f1832f2c 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1567,6 +1567,7 @@ config CRYPTO_DRBG_HASH
config CRYPTO_DRBG_CTR
bool "Enable CTR DRBG"
select CRYPTO_AES
+ depends on CRYPTO_CTR
help
Enable the CTR DRBG variant as defined in NIST SP800-90A.