The Advanced Encryption Standard (AES) cipher, also known as "Rijndael" is a popular, secure, widely used symmetric key block cipher algorithm, used officially as recommended encryption technology standard in the United States. AES operates using block size of 128 bits and symmetric keys of length128, 160, 192, 224 and 256 bits. Show
AES is Secure and Very Popular Symmetric Encryption AlgorithmThe AES symmetric encryption algorithm is considered highly secure (when configured correctly) and no significant practical attacks are known for AES in its history. AES is used internally by the most Internet Web sites today for serving Due to its wide use in the Internet secure communication, modern CPU hardware implements AES instructions at the microprocessor level to speed-up the AES encryption and decryption. The AES algorithm can operate with different key lengths, but the block size is always 128 bits. For most application 128-bit AES encryption (AES-128) is enough, but for higher encryption level, it is recommended to use AES-256 (256-bit key length). Like any other block ciphers, AES can use one of several modes of operation (CBC, ECB, CTR, …) to allow encryption of data of arbitrary length. The recommended mode for the general case and for encrypting blockchain wallets is "CTR". Most modes of operation require an initial vector (IV). When using a counter mode (CTR), i.e. AES-128-CTR (128-bit) or AES-256-CTR (256-bit) for example, first a non-secret random salt (IV) should be generated and saved along with the encrypted ciphertext output. The size of the IV is always the same as the size of the block, i.e. 128 bits (16 bytes). The AES encryption, combined with CTR block mode and random IV causes the encryption algorithm to produce different encrypted ciphertext each time, when the same input data is encrypted. This ensures that nobody can construct a dictionary to reverse back the encrypted ciphertext. AES encryption in CBC mode uses a padding algorithm (like PKCS7 or ANSI X.923) to help splitting the input data into blocks of fixed block-size (e.g. 128 bits) before passing the blocks to the AES-CBC algorithm. Most developers use the CTR mode of operation for AES, so they don't need padding. Without using a block mode, the ciphertext, generated by the AES algorithm is exactly 128 bits (16 bytes), just like the block size. The input data is also exactly 128 bits. The ciphertext, generated by the AES-CTR algorithm (AES in CTR cipher block mode) has the same size like the size of the input data. No padding is required. The ciphertext, generated by the AES-CBC algorithm (AES in CBC ciphertext mode), has size of 128 bits (16 bytes) or multiple of 128 bits. The input data should be padded before encryption and unpadded after decryption. The AES algorithm often is
used along with a password-to-key derivation function, e.g. Integrated Message Authentication Code (MAC)The AES algorithm may use
MAC (message authentication code) to check the password validity, e.g. The MAC code is typically integrated (see the concept of integrated encryption) in the algorithm's output. It is calculated from the input message, together with the encryption key. From the calculated MAC, it is impossible to reveal the input message or the key, so the MAC itself is not a secret. Some block cipher modes (like AES-GCM) integrate message authentication in the obtained ciphertext as part of their work, so you don't need to add MAC explicitly. Typically MAC is calculated and used like this:
The AES Encryption ProcessThe entire AES encryption process (password-based authenticated encryption) looks like this:
The AES Decryption ProcessThe opposite AES decryption process (password-based authenticated decryption) looks like this:
Now it is time to illustrate the above described concepts through working source code to AES encrypt / decrypt an input msg by given password. What is CCM mode in AES?CCM — AES CCM mode encryption. Cipher block chaining - message authentication code (CCM) mode is an authenticated encryption algorithm designed to provide both authentication and confidentiality during data transfer.
Which two types of attacks apply to specifically to MAC algorithms?12.4 SECURITY OF MACS:
Just as with symmetric and public-key encryption, we can group attacks on hash functions and MACs into two categories: brute-force attacks and cryptanalysis.
What encryption algorithm is used in CCMP for confidentially?CCMP uses the AES cipher to encrypt sensitive data. It employs 128-bit keys and a 48-bit initialization vector (IV), also known as a CCM nonce block, to detect replays and minimize vulnerability to replay attacks.
What are the different modes of operation in DES?Experts using DES have five different modes of operation to choose from.. Electronic Codebook (ECB). Each 64-bit block is encrypted and decrypted independently.. Cipher Block Chaining (CBC). ... . Cipher Feedback (CFB). ... . Output Feedback (OFB). ... . Counter (CTR).. |