Neil Thiessen / AES

A lightweight AES implementation with Cipher Block Chaining and Ciphertext Stealing.

Dependents:   AES_HelloWorld AES_ExtendedTests AESslave_modified_test AESslave_modified_test_27-9-2017 ... more

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AES Class Reference
Public Types | Public Member Functions

AES Class Reference

AES class. More...

#include <AES.h>

Public Types

enum  KeySize { KEY_128 = 4, KEY_192 = 6, KEY_256 = 8 }
 

Represents the different AES key sizes.

More...
enum  CipherMode { MODE_ECB, MODE_CBC }
 

Represents the different cipher modes.

More...

Public Member Functions

 AES ()
 Create a blank AES object.
 AES (const char *key, KeySize keySize, CipherMode mode=MODE_ECB, const char *iv=NULL)
 Create an AES object with the specified parameters.
 ~AES ()
 Destructor.
void setup (const char *key, KeySize keySize, CipherMode mode=MODE_ECB, const char *iv=NULL)
 Set up this AES object for encryption/decryption with the specified parameters.
void encrypt (void *data, size_t length)
 Encrypt the specified data in-place, using CTS or zero-padding if necessary.
void encrypt (const void *src, char *dest, size_t length)
 Encrypt the specified data, using CTS or zero-padding if necessary.
void decrypt (void *data, size_t length)
 Decrypt the specified data in-place, and remove the padding if necessary.
void decrypt (const char *src, void *dest, size_t length)
 Decrypt the specified data, and remove the padding if necessary.
void clear ()
 Erase any sensitive information in this AES object.

Detailed Description

AES class.

Used for encrypting/decrypting data using the AES block cipher.

Example: 

 #include "mbed.h"
 #include "AES.h"

 char message[] = {
     "Hello World!"
 };

 const char key[32] = {
     0x60, 0x3D, 0xEB, 0x10, 0x15, 0xCA, 0x71, 0xBE,
     0x2B, 0x73, 0xAE, 0xF0, 0x85, 0x7D, 0x77, 0x81,
     0x1F, 0x35, 0x2C, 0x07, 0x3B, 0x61, 0x08, 0xD7,
     0x2D, 0x98, 0x10, 0xA3, 0x09, 0x14, 0xDF, 0xF4
 };

 const char iv[16] = {
     0x74, 0x11, 0xF0, 0x45, 0xD6, 0xA4, 0x3F, 0x69,
     0x18, 0xC6, 0x75, 0x42, 0xDF, 0x4C, 0xA7, 0x84
 };

 void printData(const void* data, size_t length)
 {
     const char* dataBytes = (const char*)data;
     for (size_t i = 0; i < length; i++) {
         if ((i % 8) == 0)
             printf("\n\t");
         printf("0x%02X, ", dataBytes[i]);
     }
     printf("\n");
 }

 int main()
 {
     AES aes;

     //Print the original message
     printf("Original message: \"%s\"", message);
     printData(message, sizeof(message));

     //Encrypt the message in-place
     aes.setup(key, AES::KEY_256, AES::MODE_CBC, iv);
     aes.encrypt(message, sizeof(message));
     aes.clear();

     //Print the encrypted message
     printf("Encrypted message:");
     printData(message, sizeof(message));

     //Decrypt the message in-place
     aes.setup(key, AES::KEY_256, AES::MODE_CBC, iv);
     aes.decrypt(message, sizeof(message));
     aes.clear();

     //Print the decrypted message
     printf("Decrypted message: \"%s\"", message);
     printData(message, sizeof(message));
 }

Definition at line 85 of file AES.h.

Member Enumeration Documentation

enum CipherMode

Represents the different cipher modes.

Enumerator:
MODE_ECB 

Electronic codebook.

MODE_CBC 

Cipher block chaining.

Definition at line 98 of file AES.h.

enum KeySize

Represents the different AES key sizes.

Enumerator:
KEY_128 

128-bit AES key

KEY_192 

192-bit AES key

KEY_256 

256-bit AES key

Definition at line 90 of file AES.h.

Constructor & Destructor Documentation

AES (  )

Create a blank AES object.

Definition at line 95 of file AES.cpp.

AES ( const char *  key,
KeySize  keySize,
CipherMode  mode = MODE_ECB,
const char *  iv = NULL 
)

Create an AES object with the specified parameters.

Parameters:
keyPointer to the AES key.
keySizeThe AES key size as a KeySize enum.
modeThe cipher mode as a CipherMode enum (MODE_ECB by default).
ivPointer to the 16B initialization vector (NULL by default).

Definition at line 103 of file AES.cpp.

~AES (  )

Destructor.

Definition at line 109 of file AES.cpp.

Member Function Documentation

void clear (  )

Erase any sensitive information in this AES object.

Definition at line 328 of file AES.cpp.

void decrypt ( const char *  src,
void *  dest,
size_t  length 
)

Decrypt the specified data, and remove the padding if necessary.

Parameters:
srcPointer to the data to decrypt (minimum 16B).
destPointer to an array in which to store the decrypted data.
lengthThe length of the decrypted data without padding in bytes.

Definition at line 247 of file AES.cpp.

void decrypt ( void *  data,
size_t  length 
)

Decrypt the specified data in-place, and remove the padding if necessary.

Parameters:
dataPointer to the data to decrypt (minimum 16B).
lengthThe length of the decrypted data without padding in bytes.

Definition at line 241 of file AES.cpp.

void encrypt ( const void *  src,
char *  dest,
size_t  length 
)

Encrypt the specified data, using CTS or zero-padding if necessary.

Parameters:
srcPointer to the data to encrypt.
destPointer to an array in which to store the encrypted data (minimum 16B).
lengthThe length of the data to encrypt in bytes.

Definition at line 148 of file AES.cpp.

void encrypt ( void *  data,
size_t  length 
)

Encrypt the specified data in-place, using CTS or zero-padding if necessary.

Parameters:
dataPointer to the data to encrypt (minimum 16B for output).
lengthThe length of the data to encrypt in bytes.

Definition at line 142 of file AES.cpp.

void setup ( const char *  key,
KeySize  keySize,
CipherMode  mode = MODE_ECB,
const char *  iv = NULL 
)

Set up this AES object for encryption/decryption with the specified parameters.

Parameters:
keyPointer to the AES key.
keySizeThe AES key size as a KeySize enum.
modeThe cipher mode as a CipherMode enum (MODE_ECB by default).
ivPointer to the 16B initialization vector (NULL by default).

Definition at line 115 of file AES.cpp.

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