In computing, 56-bit encryption refers to a

key size In cryptography, key size, key length, or key space refer to the number of bits in a key used by a cryptographic algorithm (such as a cipher). Key length defines the upper-bound on an algorithm's security (i.e. a logarithmic measure of the fastest ...

of fifty-six

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

s, or seven

byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...

s, for

symmetric encryption Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between th ...

. While stronger than

40-bit encryption 40-bit encryption refers to a (now broken) key size of forty bits, or five bytes, for symmetric encryption; this represents a relatively low level of security. A forty bit length corresponds to a total of 240 possible keys. Although this is a larg ...

, this still represents a relatively low

level of security In cryptography, security level is a measure of the strength that a cryptographic primitive — such as a cipher or hash function — achieves. Security level is usually expressed as a number of "bits of security" (also security strength ...

in the context of a

brute force attack In cryptography, a brute-force attack consists of an attacker submitting many passwords or passphrases with the hope of eventually guessing correctly. The attacker systematically checks all possible passwords and passphrases until the correct ...

Description

The US government traditionally regulated encryption for reasons of national security, law enforcement and foreign policy. Encryption was regulated from 1976 by the

Arms Export Control Act The Arms Export Control Act of 1976 (Title II of , codified at ) gives the President of the United States the authority to control the import and export of defense articles and defense services. The H.R. 13680 legislation was passed by the 94th ...

until control was transferred to the

Department of Commerce The United States Department of Commerce is an executive department of the U.S. federal government concerned with creating the conditions for economic growth and opportunity. Among its tasks are gathering economic and demographic data for bu ...

in 1996. 56-bit refers to the size of a symmetric key used to encrypt data, with the number of unique possible permutations being

2^

(72,057,594,037,927,936). 56-bit encryption has its roots in

DES Des is a masculine given name, mostly a short form (hypocorism) of Desmond. People named Des include: People * Des Buckingham, English football manager * Des Corcoran, (1928–2004), Australian politician * Des Dillon (disambiguation), sever ...

, which was the official standard of the US

National Bureau of Standards The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

from 1976, and later also the

RC5 In cryptography, RC5 is a symmetric-key block cipher notable for its simplicity. Designed by Ronald Rivest in 1994, ''RC'' stands for "Rivest Cipher", or alternatively, "Ron's Code" (compare RC2 and RC4). The Advanced Encryption Standard (AES) c ...

algorithm. US government regulations required any users of stronger 56-bit symmetric keys to submit to key recovery through algorithms like CDMF or key escrow, effectively reducing the key strength to 40-bit, and thereby allowing organisations such as the

NSA The National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collectio ...

to brute-force this encryption. Furthermore, from 1996 software products

exported An export in international trade is a good produced in one country that is sold into another country or a service provided in one country for a national or resident of another country. The seller of such goods or the service provider is an ...

from the United States were not permitted to use stronger than 56-bit encryption, requiring different software editions for the US and export markets. In 1999, US allowed 56-bit encryption to be exported without key escrow or any other key recovery requirements. The advent of commerce on the Internet and faster computers raised concerns about the security of electronic transactions initially with 40-bit, and subsequently also with 56-bit encryption. In February 1997,

RSA Data Security RSA Security LLC, formerly RSA Security, Inc. and doing business as RSA, is an American computer and network security company with a focus on encryption and encryption standards. RSA was named after the initials of its co-founders, Ron Rivest ...

ran a brute force competition with a $10,000 prize to demonstrate the weakness of 56-bit encryption; the contest was won four months later. In July 1998, a successful brute-force attack was demonstrated against 56-bit encryption with

Deep Crack In cryptography, the EFF DES cracker (nicknamed "Deep Crack") is a machine built by the Electronic Frontier Foundation (EFF) in 1998, to perform a brute force search of the Data Encryption Standard (DES) cipher's key space – that is, to decr ...

in just 56 hours. In 2000, all restrictions on key length were lifted, except for exports to embargoed countries. 56-bit DES encryption is now obsolete, having been replaced as a standard in 2002 by the 128-bit (and stronger)

Advanced Encryption Standard The Advanced Encryption Standard (AES), also known by its original name Rijndael (), is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a variant ...

. DES continues to be used as a symmetric cipher in combination with Kerberos because older products do not support newer ciphers like AES.

References

{{reflist Symmetric-key cryptography History of cryptography

Description

See also

References