What does 2048 bit encryption mean?
2048-bit encryption refers to the size of an SSL certificate. SSL stands for secure sockets layer and is the way secure connections are created between your web browser and a website. The advantage of 2048-bit encryption is strength, although it is less than that of a true 2048-bit key.
A 2048-bit RSA key provides 112-bit of security. Given that TLS certificates are valid for two years maximum (soon to be decreased to one), 2048-bit RSA key length fulfills the NIST recommendation until late in this decade.
It would take a classical computer around 300 trillion years to break a RSA-2048 bit encryption key.
Measuring encryption strength
NIST tells us a 2048 bit RSA key is equivalent to a 112 bit symmetric cipher. NIST says a 2048 bit RSA key has a strength of 112 bits: i.e., there are theoretically 2112 possibilities to crack the private key.
AES 256-bit encryption is the strongest and most robust encryption standard that is commercially available today. While it is theoretically true that AES 256-bit encryption is harder to crack than AES 128-bit encryption, AES 128-bit encryption has never been cracked.
Fortunately, companies like Google, that also have a high internet presence, are recognizing the potential problems and taking steps to address them. One such solution is 2048-bit encryption.
RSA-2048 has 617 decimal digits (2,048 bits). It is the largest of the RSA numbers and carried the largest cash prize for its factorization, $200,000.
AES-256 is indeed cracked, because it doesn't hold its original 256bit security. You ask if it is secure - security isn't a yes/no question, it is 231bit secure, and common wisdom is that 128bit+ is "pretty secure", and 90bit- is close to practically broken.
RSA-4096 is a legitimate encryption cipher. It is one of the best encryption systems that you can use to protect your data in transmission. But, unfortunately, a system that is universally available can be used by miscreants as well as honest business people.
Most of the updated algorithms being used are currently "secure enough" for the time being until quantum computing is developed further specifically for bruteforcing passwords or cracking hashes. At minimum it would take a month, or up to a year to crack a single "standard" strong password of constant computing.
Why is key length 2048?
While doubling key strength delivers an exponential increase in protection -- encryption strength is directly tied to key size -- the computational power required to process 2,048-bit certificates is five to 30 times greater than that for 1,024-bit certificates.
How To Generate RSA Public and Private Key Pair with OpenSSL

RSA is more computationally intensive than AES, and much slower. It's normally used to encrypt only small amounts of data.
One of the most secure encryption types, Advanced Encryption Standard (AES) is used by governments and security organizations as well as everyday businesses for classified communications. AES uses “symmetric” key encryption.
The one-way function that is proposed for use in the creation of the TESLA keychain is the SHA256 algorithm. This Secure Hash Algorithm (SHA) acts as a standard one-way function in cryptography that is capable of taking an arbitrarily sized bit-field and creating a 256-bit output.
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There is no AES-512. AES only comes in 128, 192 and 256 bit flavors.
A typical value is 256 bits. The public key is a group element, which is much larger than the private key. A typical value is 2048 bits. So with finite field crypto the public key is much larger than the private key.
Kaspersky Lab is launching an international distributed effort to crack a 1024-bit RSA key used by the Gpcode Virus. From their website: We estimate it would take around 15 million modern computers, running for about a year, to crack such a key.
In 2003, RSA Security claimed that 1024-bit keys were likely to become crackable some time between 2006 and 2010, while 2048-bit keys are sufficient until 2030.
How secure is 4096 bit?
RSA-4096 is a legitimate encryption cipher. It is one of the best encryption systems that you can use to protect your data in transmission. But, unfortunately, a system that is universally available can be used by miscreants as well as honest business people.
Encryption algorithms using 1024-bit keys are no longer secure, due to the emergence of 'trapdoored' primes. Expert Michael Cobb explains how the encryption backdoor works. The National Institute of Standards and Technology (NIST) has recommended minimum key sizes of 2048-bits for the...
For RSA keys, the minimum size for clear RSA keys and secure RSA keys on the public key data set (PKDS) is 512 bits. The minimum size for secure RSA keys on the token key data set (TKDS) is 1024 bits and the size must be a multiple of 256.