diff options
Diffstat (limited to 'arch/arm/crypto/Kconfig')
| -rw-r--r-- | arch/arm/crypto/Kconfig | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/arm/crypto/Kconfig b/arch/arm/crypto/Kconfig index 847b7a003356..5ff49a5e9afc 100644 --- a/arch/arm/crypto/Kconfig +++ b/arch/arm/crypto/Kconfig @@ -166,10 +166,9 @@ config CRYPTO_AES_ARM config CRYPTO_AES_ARM_BS tristate "Ciphers: AES, modes: ECB/CBC/CTR/XTS (bit-sliced NEON)" depends on KERNEL_MODE_NEON + select CRYPTO_AES_ARM select CRYPTO_SKCIPHER select CRYPTO_LIB_AES - select CRYPTO_AES - select CRYPTO_CBC select CRYPTO_SIMD help Length-preserving ciphers: AES cipher algorithms (FIPS-197) @@ -183,8 +182,15 @@ config CRYPTO_AES_ARM_BS Bit sliced AES gives around 45% speedup on Cortex-A15 for CTR mode and for XTS mode encryption, CBC and XTS mode decryption speedup is around 25%. (CBC encryption speed is not affected by this driver.) - This implementation does not rely on any lookup tables so it is - believed to be invulnerable to cache timing attacks. + + The bit sliced AES code does not use lookup tables, so it is believed + to be invulnerable to cache timing attacks. However, since the bit + sliced AES code cannot process single blocks efficiently, in certain + cases table-based code with some countermeasures against cache timing + attacks will still be used as a fallback method; specifically CBC + encryption (not CBC decryption), the encryption of XTS tweaks, XTS + ciphertext stealing when the message isn't a multiple of 16 bytes, and + CTR when invoked in a context in which NEON instructions are unusable. config CRYPTO_AES_ARM_CE tristate "Ciphers: AES, modes: ECB/CBC/CTS/CTR/XTS (ARMv8 Crypto Extensions)" |