How long does it take to break a 128 bit encryption?
As shown above, even with a supercomputer, it would take 1 billion billion years to crack the 128-bit AES key using brute force attack. This is more than the age of the universe (13.75 billion years).
Today's encryption algorithms can be broken. Their security derives from the wildly impractical lengths of time it can take to do so. Let's say you're using a 128-bit AES cipher. If a quantum system had to crack a 256-bit key, it would take about as much time as a conventional computer needs to crack a 128-bit key.
- Each cipher encrypts and decrypts data in blocks of 128 bits using cryptographic keys of 128-, 192- and 256-bits, respectively. The Rijndael cipher was designed to accept additional block sizes and key lengths, but for AES, those functions were not adopted.
- You can not encrypt then decrypt with private key only, nor can you do the same with public keys alone. Remus nailed it; encrypting with the private key doesn't make much sense when the decryption key is well know and public. Also, you can derive the public key from the private key, but not vice versa.
- RSA is an algorithm used by modern computers to encrypt and decrypt messages. It is an asymmetric cryptographic algorithm. Asymmetric means that there are two different keys. This is also called public key cryptography, because one of them can be given to everyone. The other key must be kept private.
The cipher AES-256 is used among other places in SSL/TLS across the Internet. It's considered among the top ciphers. In theory it's not crackable since the combinations of keys are massive. Although NSA has categorized this in Suite B, they have also recommended using higher than 128-bit keys for encryption.
- SHA isn't encryption, it's a one-way hash function. AES (Advanced_Encryption_Standard) is a symmetric encryption standard. SHA is a family of "Secure Hash Algorithms" that have been developed by the National Security Agency. It is "symmetric" because the key allows for both encryption and decryption.
- The key difference between encryption and hashing is that encrypted strings can be reversed back into their original decrypted form if you have the right key. In symmetric key encryption, the key to both encrypt and decrypt is exactly the same. This is what most people think of when they think of encryption.
- RSA is used mostly in hybrid encryption schemes and digital signatures. In the former it is used to encrypt a symmetric key and send it to a second party who has requested it. This is because RSA is comparatively slow so you would never use it to encrypt a whole file.
128-bit encryption is a data/file encryption technique that uses a 128-bit key to encrypt and decrypt data or files. It is one of the most secure encryption methods used in most modern encryption algorithms and technologies. 128-bit encryption is considered to be logically unbreakable.
- An AES 128-bit key can be expressed as a hexadecimal string with 32 characters. It will require 24 characters in base64.
An AES 256-bit key can be expressed as a hexadecimal string with 64 characters. It will require 44 characters in base64.
- The MD5 algorithm is a widely used hash function producing a 128-bit hash value. Like most hash functions, MD5 is neither encryption nor encoding. It can be cracked by brute-force attack and suffers from extensive vulnerabilities as detailed in the security section below.
- Hashing is not encryption (it is hashing), so we do not "decrypt" MD5 hashes, since they were not "encrypted" in the first place. Hashing is one-way, but deterministic: hash twice the same value, and you get twice the same output.
Updated: 28th November 2019