Remove the duplicated boilerplate help text and add a bit of
explanation about the nature of the various AES implementations that
exist for various architectures. In particular, highlight the time
variant nature of some implementations, and the fact that they can be
omitted if required.
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
arch/arm/crypto/Kconfig | 16 ++-
arch/arm64/crypto/Kconfig | 30 +++++-
crypto/Kconfig | 104 +++++++-------------
3 files changed, 75 insertions(+), 75 deletions(-)
diff --git a/arch/arm/crypto/Kconfig b/arch/arm/crypto/Kconfig
index b9adedcc5b2e..f611127c5ef9 100644
--- a/arch/arm/crypto/Kconfig
+++ b/arch/arm/crypto/Kconfig
@@ -62,11 +62,23 @@ config CRYPTO_SHA512_ARM
using optimized ARM assembler and NEON, when available.
config CRYPTO_AES_ARM
- tristate "Scalar AES cipher for ARM"
+ tristate "Table based AES cipher for 32-bit ARM"
select CRYPTO_ALGAPI
select CRYPTO_AES
help
- Use optimized AES assembler routines for ARM platforms.
+ Table based implementation in 32-bit ARM assembler of the FIPS-197
+ Advanced Encryption Standard (AES) symmetric cipher algorithm. This
+ driver reuses the tables exposed by the generic AES driver.
+
+ For CPUs that lack the special ARMv8-CE instructions, this is the
+ fastest implementation available of the core cipher, but it may be
+ susceptible to known-plaintext attacks on the key due to the
+ correlation between the processing time and the input of the first
+ round. Therefore, it is recommended to also enable the time invariant
+ NEON based driver below (CRYPTO_AES_ARM_BS), which will supersede
+ this driver on NEON capable CPUs when using AES in CBC, CTR and XTS
+ modes. If time invariance is a requirement, this driver should not
+ be enabled.
config CRYPTO_AES_ARM_BS
tristate "Bit sliced AES using NEON instructions"
diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
index d92293747d63..bf38680a2dbb 100644
--- a/arch/arm64/crypto/Kconfig
+++ b/arch/arm64/crypto/Kconfig
@@ -42,13 +42,37 @@ config CRYPTO_CRC32_ARM64_CE
select CRYPTO_HASH
config CRYPTO_AES_ARM64
- tristate "AES core cipher using scalar instructions"
+ tristate "Table based AES cipher for 64-bit ARM"
select CRYPTO_AES
+ help
+ Table based implementation in 64-bit ARM assembler of the FIPS-197
+ Advanced Encryption Standard (AES) symmetric cipher algorithm. This
+ driver reuses the tables exposed by the generic AES driver.
+
+ For CPUs that lack the special ARMv8-CE instructions, this is the
+ fastest implementation available of the core cipher, but it may be
+ susceptible to known-plaintext attacks on the key due to the
+ correlation between the processing time and the input of the first
+ round. Therefore, it is recommended to also enable the time invariant
+ drivers below (CRYPTO_AES_ARM64_NEON_BLK and CRYPTO_AES_ARM64_BS),
+ which will supersede this driver when using AES in the specific modes
+ that they implement. If time invariance is a requirement, this driver
+ should not be enabled.
config CRYPTO_AES_ARM64_CE
- tristate "AES core cipher using ARMv8 Crypto Extensions"
- depends on ARM64 && KERNEL_MODE_NEON
+ tristate "AES cipher using ARMv8 Crypto Extensions"
+ depends on KERNEL_MODE_NEON
select CRYPTO_ALGAPI
+ help
+ Implementation in assembler of the FIPS-197 Advanced Encryption
+ Standard (AES) symmetric cipher algorithm, using instructions from
+ ARM's optional ARMv8 Crypto Extensions. This implementation is time
+ invariant, and is by far the preferred option for CPUs that support
+ this extension.
+
+ If in doubt, enable as a module: it will be loaded automatically on
+ CPUs that support it, and supersede other implementations of the AES
+ cipher.
config CRYPTO_AES_ARM64_CE_CCM
tristate "AES in CCM mode using ARMv8 Crypto Extensions"
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 8f4b9f3381e2..9bec9f7a81d9 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -909,51 +909,37 @@ config CRYPTO_AES
block.
config CRYPTO_AES_586
- tristate "AES cipher algorithms (i586)"
+ tristate "Table based AES cipher for 32-bit x86"
depends on (X86 || UML_X86) && !64BIT
select CRYPTO_ALGAPI
select CRYPTO_AES
help
- AES cipher algorithms (FIPS-197). AES uses the Rijndael
- algorithm.
-
- Rijndael appears to be consistently a very good performer in
- both hardware and software across a wide range of computing
- environments regardless of its use in feedback or non-feedback
- modes. Its key setup time is excellent, and its key agility is
- good. Rijndael's very low memory requirements make it very well
- suited for restricted-space environments, in which it also
- demonstrates excellent performance. Rijndael's operations are
- among the easiest to defend against power and timing attacks.
-
- The AES specifies three key sizes: 128, 192 and 256 bits
-
- See <http://csrc.nist.gov/encryption/aes/> for more information.
+ Table based implementation in 32-bit x86 assembler of the FIPS-197
+ Advanced Encryption Standard (AES) symmetric cipher algorithm. For
+ older 32-bit x86 CPUs that lack the special AES-NI instructions, it
+ is the fastest implementation available, but it may be susceptible to
+ known-plaintext attacks on the key due to the correlation between the
+ processing time and the input of the first round. It reuses the
+ tables exposed by the generic AES driver. If time invariance is a
+ requirement, this driver should not be enabled.
config CRYPTO_AES_X86_64
- tristate "AES cipher algorithms (x86_64)"
+ tristate "Table based AES cipher for 64-bit x86"
depends on (X86 || UML_X86) && 64BIT
select CRYPTO_ALGAPI
select CRYPTO_AES
help
- AES cipher algorithms (FIPS-197). AES uses the Rijndael
- algorithm.
-
- Rijndael appears to be consistently a very good performer in
- both hardware and software across a wide range of computing
- environments regardless of its use in feedback or non-feedback
- modes. Its key setup time is excellent, and its key agility is
- good. Rijndael's very low memory requirements make it very well
- suited for restricted-space environments, in which it also
- demonstrates excellent performance. Rijndael's operations are
- among the easiest to defend against power and timing attacks.
-
- The AES specifies three key sizes: 128, 192 and 256 bits
-
- See <http://csrc.nist.gov/encryption/aes/> for more information.
+ Table based implementation in 64-bit x86 assembler of the FIPS-197
+ Advanced Encryption Standard (AES) symmetric cipher algorithm. For
+ older 64-bit x86 CPUs that lack the special AES-NI instructions, it
+ is the fastest implementation available, but it may be susceptible to
+ known-plaintext attacks on the key due to the correlation between the
+ processing time and the input of the first round. It reuses the
+ tables exposed by the generic AES driver. If time invariance is a
+ requirement, this driver should not be enabled.
config CRYPTO_AES_NI_INTEL
- tristate "AES cipher algorithms (AES-NI)"
+ tristate "AES cipher for x86 using AES-NI instructions"
depends on X86
select CRYPTO_AEAD
select CRYPTO_AES_CORE
@@ -962,52 +948,29 @@ config CRYPTO_AES_NI_INTEL
select CRYPTO_GLUE_HELPER_X86 if 64BIT
select CRYPTO_SIMD
help
- Use Intel AES-NI instructions for AES algorithm.
-
- AES cipher algorithms (FIPS-197). AES uses the Rijndael
- algorithm.
-
- Rijndael appears to be consistently a very good performer in
- both hardware and software across a wide range of computing
- environments regardless of its use in feedback or non-feedback
- modes. Its key setup time is excellent, and its key agility is
- good. Rijndael's very low memory requirements make it very well
- suited for restricted-space environments, in which it also
- demonstrates excellent performance. Rijndael's operations are
- among the easiest to defend against power and timing attacks.
-
- The AES specifies three key sizes: 128, 192 and 256 bits
-
- See <http://csrc.nist.gov/encryption/aes/> for more information.
+ Implementation in x86 assembler of the FIPS-197 Advanced Encryption
+ Standard (AES) symmetric cipher algorithm, using instructions from
+ Intel's optional AES-NI ISA extension. This implementation is time
+ invariant, and is by far the preferred option for CPUs that support
+ this extension.
In addition to AES cipher algorithm support, the acceleration
for some popular block cipher mode is supported too, including
ECB, CBC, LRW, PCBC, XTS. The 64 bit version has additional
acceleration for CTR.
+ If in doubt, enable as a module: it will be loaded automatically on
+ CPUs that support it, and supersede other implementations of the AES
+ cipher.
+
config CRYPTO_AES_SPARC64
- tristate "AES cipher algorithms (SPARC64)"
+ tristate "AES cipher for SPARC64 using crypto opcodes"
depends on SPARC64
select CRYPTO_CRYPTD
select CRYPTO_ALGAPI
help
- Use SPARC64 crypto opcodes for AES algorithm.
-
- AES cipher algorithms (FIPS-197). AES uses the Rijndael
- algorithm.
-
- Rijndael appears to be consistently a very good performer in
- both hardware and software across a wide range of computing
- environments regardless of its use in feedback or non-feedback
- modes. Its key setup time is excellent, and its key agility is
- good. Rijndael's very low memory requirements make it very well
- suited for restricted-space environments, in which it also
- demonstrates excellent performance. Rijndael's operations are
- among the easiest to defend against power and timing attacks.
-
- The AES specifies three key sizes: 128, 192 and 256 bits
-
- See <http://csrc.nist.gov/encryption/aes/> for more information.
+ Implementation of the FIPS-197 Advanced Encryption Standard (AES)
+ symmetric cipher algorithm, using SPARC64 crypto opcodes.
In addition to AES cipher algorithm support, the acceleration
for some popular block cipher mode is supported too, including
@@ -1017,8 +980,9 @@ config CRYPTO_AES_PPC_SPE
tristate "AES cipher algorithms (PPC SPE)"
depends on PPC && SPE
help
- AES cipher algorithms (FIPS-197). Additionally the acceleration
- for popular block cipher modes ECB, CBC, CTR and XTS is supported.
+ Implementation of the FIPS-197 Advanced Encryption Standard (AES)
+ symmetric cipher algorithm. Additionally, the acceleration for
+ popular block cipher modes ECB, CBC, CTR and XTS is supported.
This module should only be used for low power (router) devices
without hardware AES acceleration (e.g. caam crypto). It reduces the
size of the AES tables from 16KB to 8KB + 256 bytes and mitigates
--
2.9.3
