Is AES and AES-CBC the same?
AES-CBC is an encryption algorithm, whereas SHA is a hashing algorithm, they are seperate algorithms. AES-GCM algorithm performs both encryption and hashing functions without requiring a seperate hashing algorithm, it is the latest Suite B Next Generation algorithm and probably not supported on as ASA 5505.
AES-GCM is a more secure cipher than AES-CBC, because AES-CBC, operates by XOR'ing (eXclusive OR) each block with the previous block and cannot be written in parallel. This affects performance due to the complex mathematics involved requiring serial encryption.
CBC (short for cipher-block chaining) is a AES block cipher mode that trumps the ECB mode in hiding away patterns in the plaintext. CBC mode achieves this by XOR-ing the first plaintext block (B1) with an initialization vector before encrypting it.
Out of 128-bit, 192-bit, and 256-bit AES encryption, 256-bit AES encryption is technically the most secure because of its key length size. Some go as far as to label 256-bit AES encryption overkill because it, based on some estimations, would take trillions of years to crack using a brute-force attack.
From a cryptographic perspective, though, both AES-CBC and AES-GCM are highly secure. GCM provides authentication, removing the need for an HMAC SHA hashing function. It is also slightly faster than CBC because it uses hardware acceleration (by threading to multiple processor cores).
XTS mode is the most common if you are encoding a random accessible data (like a hard disk or RAM). OCB is by far the best mode, as it allows encryption and authentication in a single pass.
Both the AES-CBC and AES-GCM are able to secure your valuable data with a good implementation. but to prevent complex CBC attacks such as Chosen Plaintext Attack(CPA) and Chosen Ciphertext Attack(CCA) it is necessary to use Authenticated Encryption.
Microsoft believes that it's no longer safe to decrypt data encrypted with the Cipher-Block-Chaining (CBC) mode of symmetric encryption when verifiable padding has been applied without first ensuring the integrity of the ciphertext, except for very specific circumstances.
Our best guidance is that AES-128 provides more than adequate security while being faster and more resource-efficient but readers who want that extra security provided by greater key sizes and more rounds in the algorithm should choose AES-256.
The Cipher Block Chaining (CBC) mode is a typical block cipher mode of operation using block cipher algorithm. In this version, we provide Data Encryption Standard (DES) and Advanced Encryption Standard (AES) processing ability, the cipherkey length for DES should be 64 bits, and 128/192/256 bits for AES.
What is the biggest advantage of CBC mode of operation?
A major advantage of CBC mode is that, while encryption must be performed sequentially, decryption can be parallelized. The first IV is a public value and all other blocks use a ciphertext as an IV, which are public. This can make decryption faster than other block cipher modes of operation.
In CBC mode, the current plaintext block is added to the previous ciphertext block, and then the result is encrypted with the key. Decryption is thus the reverse process, which involves decrypting the current ciphertext and then adding the previous ciphertext block to the result.
AES 256 is virtually impenetrable using brute-force methods. While a 56-bit DES key can be cracked in less than a day, AES would take billions of years to break using current computing technology. Hackers would be foolish to even attempt this type of attack. Nevertheless, no encryption system is entirely secure.
In today's level of technology, it is still impossible to break or brute-force a 256-bit encryption algorithm. In fact, with the kind of computers currently available to the public it would take literally billions of years to break this type of encryption.
Even if you use Tianhe-2 (MilkyWay-2), the fastest supercomputer in the world, it will take millions of years to crack 256-bit AES encryption.
CBC has the advantage over the ECB mode in that the XORing process hides plaintext patterns. Even if the first plaintext block and third plaintext block were the exact same segment of plaintext, it is highly unlikely that the first ciphertext block and third ciphertext block would be the same.
CBC is widely used in many encrypted Flash drives. AES-XTS Block Cipher Mode. Originally specified as IEEE Std 1619-2007, NIST added XTS to the list of AES block cipher modes in 2010. XTS is the newest block cipher mode and is the cipher mode used by DataTraveler 4000G2 and DataTraveler Vault Privacy 3.0.
AES has never been cracked yet and is safe against any brute force attacks contrary to belief and arguments. However, the key size used for encryption should always be large enough that it could not be cracked by modern computers despite considering advancements in processor speeds based on Moore's law.
Brute-force attacks on a 256-bit key are impossible (physically impossible, actually). However, mathematical weaknesses in AES could be discovered in the future (or could already have been discovered and kept secret) that would make it feasible to decrypt AES-encrypted data without the key.
The EE Times points out that even using a supercomputer, a “brute force” attack would take one billion years to crack AES 128-bit encryption.
Are CBC ciphers insecure?
Cipher Block Chaining:
Additionally, the CBC mode is vulnerable to plain-text attacks in TLS 1.0, SSL 3.0 and lower. A fix has been introduced with TLS 1.2 in form of the GCM mode which is not vulnerable to the BEAST attack.
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GCM = Galois/Counter Mode, and CBC = Cipher Block Chaining... other definitions include MAC (Message Authentication Code), IV (Initialisation Vector), and CTR (CounTeR Mode).
AES-GCM is a block cipher mode of operation that provides high speed of authenticated encryption and data integrity. Todays, the level of privacy protection is insufficient and make the data is been hacked easily.
GCM is defined for block ciphers with a block size of 128 bits. Galois Message Authentication Code (GMAC) is an authentication-only variant of the GCM which can form an incremental message authentication code. Both GCM and GMAC can accept initialization vectors of arbitrary length.