Ciphers: AES, modes: ECB/CBC/CTR/XTS (bit-sliced NEON)
modulename: aes-arm-bs.ko
configname: CONFIG_CRYPTO_AES_ARM_BS
Linux Kernel Configuration
└─>Cryptographic API
└─>Accelerated Cryptographic Algorithms for CPU (arm)
└─>Ciphers: AES, modes: ECB/CBC/CTR/XTS (bit-sliced NEON)
In linux kernel since version 3.10 (release Date: 2013-06-30)
Length-preserving ciphers: AES cipher algorithms (FIPS-197)
with block cipher modes:
- ECB (Electronic Codebook) mode (NIST SP800-38A)
- CBC (Cipher Block Chaining) mode (NIST SP800-38A)
- CTR (Counter) mode (NIST SP800-38A)
- XTS (XOR Encrypt XOR with ciphertext stealing) mode (NIST SP800-38E
and IEEE 1619)
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.)
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.
with block cipher modes:
- ECB (Electronic Codebook) mode (NIST SP800-38A)
- CBC (Cipher Block Chaining) mode (NIST SP800-38A)
- CTR (Counter) mode (NIST SP800-38A)
- XTS (XOR Encrypt XOR with ciphertext stealing) mode (NIST SP800-38E
and IEEE 1619)
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.)
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.