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Improve AES documentation

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- Separate "\file" blocks from copyright, so that Doxygen doesn't repeat
  the copyright information in all the Detailed Descriptions.
- Improve phrasing and clarity of functions, parameters, defines and enums.

GitHub PR: #1292
This commit is contained in:
Rose Zadik 2018-01-22 11:48:23 +00:00 committed by Jaeden Amero
parent 3b8fbaab87
commit 7f44127c71
2 changed files with 199 additions and 131 deletions
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328
include/mbedtls/aes.h
View file

@ -1,10 +1,18 @@
/**
* \file aes.h
*
* \brief AES block cipher
* \brief The Advanced Encryption Standard (AES) specifies a FIPS-approved
* cryptographic algorithm that can be used to protect electronic
* data.
*
* The AES algorithm is a symmetric block cipher that can
* encrypt and decrypt information. For more information, see
* <em>FIPS Publication 197: Advanced Encryption Standard</em> and
* <em>ISO/IEC 18033-2:2006: Information technology -- Security
* techniques -- Encryption algorithms -- Part 2: Asymmetric
* ciphers</em>.
*/
/*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
/* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
@ -19,8 +27,9 @@
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
* This file is part of Mbed TLS (https://tls.mbed.org)
*/
#ifndef MBEDTLS_AES_H
#define MBEDTLS_AES_H
@ -34,15 +43,15 @@
#include <stdint.h>
/* padlock.c and aesni.c rely on these values! */
#define MBEDTLS_AES_ENCRYPT 1
#define MBEDTLS_AES_DECRYPT 0
#define MBEDTLS_AES_ENCRYPT 1 /**< AES encryption. */
#define MBEDTLS_AES_DECRYPT 0 /**< AES decryption. */
/* Error codes in range 0x0020-0x0022 */
#define MBEDTLS_ERR_AES_INVALID_KEY_LENGTH -0x0020 /**< Invalid key length. */
#define MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH -0x0022 /**< Invalid data input length. */
/* Error codes in range 0x0023-0x0025 */
#define MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE -0x0023 /**< Feature not available, e.g. unsupported AES key size. */
#define MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE -0x0023 /**< Feature not available. For example, an unsupported AES key size. */
#define MBEDTLS_ERR_AES_HW_ACCEL_FAILED -0x0025 /**< AES hardware accelerator failed. */
#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
@ -59,68 +68,90 @@ extern "C" {
#endif
/**
* \brief AES context structure
*
* \note buf is able to hold 32 extra bytes, which can be used:
* - for alignment purposes if VIA padlock is used, and/or
* - to simplify key expansion in the 256-bit case by
* generating an extra round key
* \brief The AES context-type definition.
*/
typedef struct
{
int nr; /*!< number of rounds */
uint32_t *rk; /*!< AES round keys */
uint32_t buf[68]; /*!< unaligned data */
int nr; /*!< The number of rounds. */
uint32_t *rk; /*!< AES round keys. */
uint32_t buf[68]; /*!< Unaligned data buffer. This buffer can
hold 32 extra Bytes, which can be used for
one of the following purposes:
<ul><li>Alignment if VIA padlock is
used.</li>
<li>Simplifying key expansion in the 256-bit
case by generating an extra round key.
</li></ul> */
}
mbedtls_aes_context;
/**
* \brief Initialize AES context
* \brief This function initializes the specified AES context.
*
* \param ctx AES context to be initialized
* It must be the first API called before using
* the context.
*
* \param ctx The AES context to initialize.
*/
void mbedtls_aes_init( mbedtls_aes_context *ctx );
/**
* \brief Clear AES context
* \brief This function releases and clears the specified AES context.
*
* \param ctx AES context to be cleared
* \param ctx The AES context to clear.
*/
void mbedtls_aes_free( mbedtls_aes_context *ctx );
/**
* \brief AES key schedule (encryption)
* \brief This function sets the encryption key.
*
* \param ctx AES context to be initialized
* \param key encryption key
* \param keybits must be 128, 192 or 256
* \param ctx The AES context to which the key should be bound.
* \param key The encryption key.
* \param keybits The size of data passed in bits. Valid options are:
* <ul><li>128 bits</li>
* <li>192 bits</li>
* <li>256 bits</li></ul>
*
* \return 0 if successful, or MBEDTLS_ERR_AES_INVALID_KEY_LENGTH
* \return \c 0 on success or #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH
* on failure.
*/
int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
unsigned int keybits );
/**
* \brief AES key schedule (decryption)
* \brief This function sets the decryption key.
*
* \param ctx AES context to be initialized
* \param key decryption key
* \param keybits must be 128, 192 or 256
* \param ctx The AES context to which the key should be bound.
* \param key The decryption key.
* \param keybits The size of data passed. Valid options are:
* <ul><li>128 bits</li>
* <li>192 bits</li>
* <li>256 bits</li></ul>
*
* \return 0 if successful, or MBEDTLS_ERR_AES_INVALID_KEY_LENGTH
* \return \c 0 on success, or #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
*/
int mbedtls_aes_setkey_dec( mbedtls_aes_context *ctx, const unsigned char *key,
unsigned int keybits );
/**
* \brief AES-ECB block encryption/decryption
* \brief This function performs an AES single-block encryption or
* decryption operation.
*
* \param ctx AES context
* \param mode MBEDTLS_AES_ENCRYPT or MBEDTLS_AES_DECRYPT
* \param input 16-byte input block
* \param output 16-byte output block
* It performs the operation defined in the \p mode parameter
* (encrypt or decrypt), on the input data buffer defined in
* the \p input parameter.
*
* \return 0 if successful
* mbedtls_aes_init(), and either mbedtls_aes_setkey_enc() or
* mbedtls_aes_setkey_dec() must be called before the first
* call to this API with the same context.
*
* \param ctx The AES context to use for encryption or decryption.
* \param mode The AES operation: #MBEDTLS_AES_ENCRYPT or
* #MBEDTLS_AES_DECRYPT.
* \param input The 16-Byte buffer holding the input data.
* \param output The 16-Byte buffer holding the output data.
* \return \c 0 on success.
*/
int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
int mode,
@ -129,26 +160,40 @@ int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
#if defined(MBEDTLS_CIPHER_MODE_CBC)
/**
* \brief AES-CBC buffer encryption/decryption
* Length should be a multiple of the block
* size (16 bytes)
* \brief This function performs an AES-CBC encryption or decryption operation
* on full blocks.
*
* \note Upon exit, the content of the IV is updated so that you can
* call the function same function again on the following
* block(s) of data and get the same result as if it was
* encrypted in one call. This allows a "streaming" usage.
* If on the other hand you need to retain the contents of the
* IV, you should either save it manually or use the cipher
* module instead.
* It performs the operation defined in the \p mode
* parameter (encrypt/decrypt), on the input data buffer defined in
* the \p input parameter.
*
* \param ctx AES context
* \param mode MBEDTLS_AES_ENCRYPT or MBEDTLS_AES_DECRYPT
* \param length length of the input data
* \param iv initialization vector (updated after use)
* \param input buffer holding the input data
* \param output buffer holding the output data
* It can be called as many times as needed, until all the input
* data is processed. mbedtls_aes_init(), and either
* mbedtls_aes_setkey_enc() or mbedtls_aes_setkey_dec() must be called
* before the first call to this API with the same context.
*
* \return 0 if successful, or MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
* \note This function operates on aligned blocks, that is, the input size
* must be a multiple of the AES block size of 16 Bytes.
*
* \note Upon exit, the content of the IV is updated so that you can
* call the same function again on the next
* block(s) of data and get the same result as if it was
* encrypted in one call. This allows a "streaming" usage.
* If you need to retain the contents of the IV, you should
* either save it manually or use the cipher module instead.
*
*
* \param ctx The AES context to use for encryption or decryption.
* \param mode The AES operation: #MBEDTLS_AES_ENCRYPT or
* #MBEDTLS_AES_DECRYPT.
* \param length The length of the input data in Bytes. This must be a
* multiple of the block size (16 Bytes).
* \param iv Initialization vector (updated after use).
* \param input The buffer holding the input data.
* \param output The buffer holding the output data.
*
* \return \c 0 on success, or #MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
* on failure.
*/
int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
int mode,
@ -160,29 +205,38 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
#if defined(MBEDTLS_CIPHER_MODE_CFB)
/**
* \brief AES-CFB128 buffer encryption/decryption.
* \brief This function performs an AES-CFB128 encryption or decryption
* operation.
*
* Note: Due to the nature of CFB you should use the same key schedule for
* both encryption and decryption. So a context initialized with
* mbedtls_aes_setkey_enc() for both MBEDTLS_AES_ENCRYPT and MBEDTLS_AES_DECRYPT.
* It performs the operation defined in the \p mode
* parameter (encrypt or decrypt), on the input data buffer
* defined in the \p input parameter.
*
* \note Upon exit, the content of the IV is updated so that you can
* call the function same function again on the following
* block(s) of data and get the same result as if it was
* encrypted in one call. This allows a "streaming" usage.
* If on the other hand you need to retain the contents of the
* IV, you should either save it manually or use the cipher
* module instead.
* For CFB, you must set up the context with mbedtls_aes_setkey_enc(),
* regardless of whether you are performing an encryption or decryption
* operation, that is, regardless of the \p mode parameter. This is
* because CFB mode uses the same key schedule for encryption and
* decryption.
*
* \param ctx AES context
* \param mode MBEDTLS_AES_ENCRYPT or MBEDTLS_AES_DECRYPT
* \param length length of the input data
* \param iv_off offset in IV (updated after use)
* \param iv initialization vector (updated after use)
* \param input buffer holding the input data
* \param output buffer holding the output data
* \note Upon exit, the content of the IV is updated so that you can
* call the same function again on the next
* block(s) of data and get the same result as if it was
* encrypted in one call. This allows a "streaming" usage.
* If you need to retain the contents of the
* IV, you must either save it manually or use the cipher
* module instead.
*
* \return 0 if successful
*
* \param ctx The AES context to use for encryption or decryption.
* \param mode The AES operation: #MBEDTLS_AES_ENCRYPT or
* #MBEDTLS_AES_DECRYPT.
* \param length The length of the input data.
* \param iv_off The offset in IV (updated after use).
* \param iv The initialization vector (updated after use).
* \param input The buffer holding the input data.
* \param output The buffer holding the output data.
*
* \return \c 0 on success.
*/
int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
int mode,
@ -193,28 +247,36 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
unsigned char *output );
/**
* \brief AES-CFB8 buffer encryption/decryption.
* \brief This function performs an AES-CFB8 encryption or decryption
* operation.
*
* Note: Due to the nature of CFB you should use the same key schedule for
* both encryption and decryption. So a context initialized with
* mbedtls_aes_setkey_enc() for both MBEDTLS_AES_ENCRYPT and MBEDTLS_AES_DECRYPT.
* It performs the operation defined in the \p mode
* parameter (encrypt/decrypt), on the input data buffer defined
* in the \p input parameter.
*
* \note Upon exit, the content of the IV is updated so that you can
* call the function same function again on the following
* block(s) of data and get the same result as if it was
* encrypted in one call. This allows a "streaming" usage.
* If on the other hand you need to retain the contents of the
* IV, you should either save it manually or use the cipher
* module instead.
* Due to the nature of CFB, you must use the same key schedule for
* both encryption and decryption operations. Therefore, you must
* use the context initialized with mbedtls_aes_setkey_enc() for
* both #MBEDTLS_AES_ENCRYPT and #MBEDTLS_AES_DECRYPT.
*
* \param ctx AES context
* \param mode MBEDTLS_AES_ENCRYPT or MBEDTLS_AES_DECRYPT
* \param length length of the input data
* \param iv initialization vector (updated after use)
* \param input buffer holding the input data
* \param output buffer holding the output data
* \note Upon exit, the content of the IV is updated so that you can
* call the same function again on the next
* block(s) of data and get the same result as if it was
* encrypted in one call. This allows a "streaming" usage.
* If you need to retain the contents of the
* IV, you should either save it manually or use the cipher
* module instead.
*
* \return 0 if successful
*
* \param ctx The AES context to use for encryption or decryption.
* \param mode The AES operation: #MBEDTLS_AES_ENCRYPT or
* #MBEDTLS_AES_DECRYPT
* \param length The length of the input data.
* \param iv The initialization vector (updated after use).
* \param input The buffer holding the input data.
* \param output The buffer holding the output data.
*
* \return \c 0 on success.
*/
int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
int mode,
@ -226,26 +288,32 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
#if defined(MBEDTLS_CIPHER_MODE_CTR)
/**
* \brief AES-CTR buffer encryption/decryption
* \brief This function performs an AES-CTR encryption or decryption
* operation.
*
* Warning: You have to keep the maximum use of your counter in mind!
* This function performs the operation defined in the \p mode
* parameter (encrypt/decrypt), on the input data buffer
* defined in the \p input parameter.
*
* Note: Due to the nature of CTR you should use the same key schedule for
* both encryption and decryption. So a context initialized with
* mbedtls_aes_setkey_enc() for both MBEDTLS_AES_ENCRYPT and MBEDTLS_AES_DECRYPT.
* Due to the nature of CTR, you must use the same key schedule
* for both encryption and decryption operations. Therefore, you
* must use the context initialized with mbedtls_aes_setkey_enc()
* for both #MBEDTLS_AES_ENCRYPT and #MBEDTLS_AES_DECRYPT.
*
* \param ctx AES context
* \param length The length of the data
* \param nc_off The offset in the current stream_block (for resuming
* within current cipher stream). The offset pointer to
* should be 0 at the start of a stream.
* \param nonce_counter The 128-bit nonce and counter.
* \param stream_block The saved stream-block for resuming. Is overwritten
* by the function.
* \param input The input data stream
* \param output The output data stream
* \warning You must keep the maximum use of your counter in mind.
*
* \return 0 if successful
* \param ctx The AES context to use for encryption or decryption.
* \param length The length of the input data.
* \param nc_off The offset in the current \p stream_block, for
* resuming within the current cipher stream. The
* offset pointer should be 0 at the start of a stream.
* \param nonce_counter The 128-bit nonce and counter.
* \param stream_block The saved stream block for resuming. This is
* overwritten by the function.
* \param input The buffer holding the input data.
* \param output The buffer holding the output data.
*
* \return \c 0 on success.
*/
int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
size_t length,
@ -257,30 +325,30 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
#endif /* MBEDTLS_CIPHER_MODE_CTR */
/**
* \brief Internal AES block encryption function
* (Only exposed to allow overriding it,
* see MBEDTLS_AES_ENCRYPT_ALT)
* \brief Internal AES block encryption function. This is only
* exposed to allow overriding it using
* \c MBEDTLS_AES_ENCRYPT_ALT.
*
* \param ctx AES context
* \param input Plaintext block
* \param output Output (ciphertext) block
* \param ctx The AES context to use for encryption.
* \param input The plaintext block.
* \param output The output (ciphertext) block.
*
* \return 0 if successful
* \return \c 0 on success.
*/
int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] );
/**
* \brief Internal AES block decryption function
* (Only exposed to allow overriding it,
* see MBEDTLS_AES_DECRYPT_ALT)
* \brief Internal AES block decryption function. This is only
* exposed to allow overriding it using see
* \c MBEDTLS_AES_DECRYPT_ALT.
*
* \param ctx AES context
* \param input Ciphertext block
* \param output Output (plaintext) block
* \param ctx The AES context to use for decryption.
* \param input The ciphertext block.
* \param output The output (plaintext) block.
*
* \return 0 if successful
* \return \c 0 on success.
*/
int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx,
const unsigned char input[16],
@ -296,11 +364,11 @@ int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx,
* \brief Deprecated internal AES block encryption function
* without return value.
*
* \deprecated Superseded by mbedtls_aes_encrypt_ext() in 2.5.0
* \deprecated Superseded by mbedtls_aes_encrypt_ext() in 2.5.0.
*
* \param ctx AES context
* \param input Plaintext block
* \param output Output (ciphertext) block
* \param ctx The AES context to use for encryption.
* \param input Plaintext block.
* \param output Output (ciphertext) block.
*/
MBEDTLS_DEPRECATED void mbedtls_aes_encrypt( mbedtls_aes_context *ctx,
const unsigned char input[16],
@ -310,11 +378,11 @@ MBEDTLS_DEPRECATED void mbedtls_aes_encrypt( mbedtls_aes_context *ctx,
* \brief Deprecated internal AES block decryption function
* without return value.
*
* \deprecated Superseded by mbedtls_aes_decrypt_ext() in 2.5.0
* \deprecated Superseded by mbedtls_aes_decrypt_ext() in 2.5.0.
*
* \param ctx AES context
* \param input Ciphertext block
* \param output Output (plaintext) block
* \param ctx The AES context to use for decryption.
* \param input Ciphertext block.
* \param output Output (plaintext) block.
*/
MBEDTLS_DEPRECATED void mbedtls_aes_decrypt( mbedtls_aes_context *ctx,
const unsigned char input[16],
@ -336,9 +404,9 @@ extern "C" {
#endif
/**
* \brief Checkup routine
* \brief Checkup routine.
*
* \return 0 if successful, or 1 if the test failed
* \return \c 0 on success, or \c 1 on failure.
*/
int mbedtls_aes_self_test( int verbose );

2
library/error.c
View file

@ -569,7 +569,7 @@ void mbedtls_strerror( int ret, char *buf, size_t buflen )
if( use_ret == -(MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH) )
mbedtls_snprintf( buf, buflen, "AES - Invalid data input length" );
if( use_ret == -(MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE) )
mbedtls_snprintf( buf, buflen, "AES - Feature not available, e.g. unsupported AES key size" );
mbedtls_snprintf( buf, buflen, "AES - Feature not available. For example, an unsupported AES key size" );
if( use_ret == -(MBEDTLS_ERR_AES_HW_ACCEL_FAILED) )
mbedtls_snprintf( buf, buflen, "AES - AES hardware accelerator failed" );
#endif /* MBEDTLS_AES_C */