Multiple encryption is the serve of encrypting an already encrypted message one or more times, either using the lapp or a different algorithm. It is besides known as cascade encryption, cascade ciphering, multiple encryption, and superencipherment. Superencryption refers to the outer-level encoding of a multiple encoding. Some cryptographers, like Matthew Green of Johns Hopkins University, say multiple encoding addresses a problem that by and large does n’t exist : Modern ciphers rarely get broken… You’re far more likely to get hit by malware or an implementation bug than you are to suffer a catastrophic attack on AES. [ 1 ] …. and in that quote lies the reason for multiple encoding, namely poor people implementation. Using two different cryptomodules and keying processes from two different vendors requires both vendors ‘ wares to be compromised for security to fail completely .
mugwump keys [edit ]
Picking any two ciphers, if the key used is the lapp for both, the second gear calculate could possibly undo the first nothing, partially or wholly. This is true of ciphers where the decoding work is precisely the same as the encoding process—the moment code would completely undo the first. If an attacker were to recover the key through cryptanalysis of the first encoding level, the attacker could possibly decrypt all the remaining layers, assuming the same key is used for all layers.
Reading: Multiple encryption – Wikipedia
To prevent that risk, one can use keys that are statistically independent for each level ( e.g. freelancer RNGs ). ideally each identify should have break and different generation, sharing, and management processes .
independent Initialization Vectors [edit ]
For en/decryption processes that necessitate sharing an Initialization Vector ( IV ) / nonce these are typically, openly shared or made known to the recipient ( and everyone else ). Its good security policy never to provide the same datum in both plaintext and ciphertext when using the same key and IV. Therefore, its commend (although at this moment without specific evidence) to use distinguish IVs for each level of encoding .
importance of the first layer [edit ]
With the exception of the erstwhile embroider, no nothing has been theoretically proven to be unbreakable. Furthermore, some recurring properties may be found in the ciphertexts generated by the first zero. Since those ciphertexts are the plaintexts used by the second zero, the second zero may be rendered vulnerable to attacks based on known plaintext properties ( see references below ). This is the lawsuit when the beginning layer is a program P that always adds the like string S of characters at the beginning ( or end ) of all ciphertexts ( normally known as a magic number ). When found in a file, the string S allows an operate system to know that the program P has to be launched in order to decrypt the file. This string should be removed before adding a second level. To prevent this kind of attack, one can use the method acting provided by Bruce Schneier : [ 2 ]
- Generate a random pad R of the same size as the plaintext.
- Encrypt R using the first cipher and key.
- XOR the plaintext with the pad, then encrypt the result using the second cipher and a different (!) key.
- Concatenate both ciphertexts in order to build the final ciphertext.
A cryptanalyst must break both ciphers to get any data. This will, however, have the drawback of making the ciphertext twice arsenic long as the original plaintext. eminence, however, that a weak inaugural nothing may merely make a second nothing that is vulnerable to a chosen plaintext assail besides vulnerable to a known plaintext attack. however, a barricade nothing must not be vulnerable to a chosen plaintext attack to be considered procure. therefore, the second cipher described above is not impregnable under that definition, either. consequently, both ciphers still need to be broken. The attack illustrates why impregnable assumptions are made about secure stop ciphers and ciphers that are even partially broken should never be used.
The Rule of Two [edit ]
The Rule of Two is a data security principle from the NSA ‘s commercial Solutions for Classified Program ( CSfC ). [ 3 ] It specifies two wholly independent layers of cryptanalysis to protect data. For exercise, data could be protected by both hardware encoding at its lowest tied and software encoding at the application layer. It could mean using two FIPS -validated software cryptomodules from different vendors to en/decrypt data. The importance of seller and/or model diverseness between the layers of components centers around removing the possibility that the manufacturers or models will share a vulnerability. This way if one components is compromised there is still an entire level of encoding protecting the information at rest or in transit. The CSfC Program offers solutions to achieve diversity in two ways. “ The first is to implement each layer using components produced by different manufacturers. The second is to use components from the same manufacturer, where that manufacturer has provided NSA with sufficient attest that the implementations of the two components are independent of one another. ” [ 4 ] The principle is practiced in the NSA ‘s secure mobile telephone called Fishbowl. [ 5 ] The phones use two layers of encoding protocols, IPsec and Secure Real-time Transport Protocol ( SRTP ), to protect voice communications. The Samsung Galaxy S9 Tactical Edition is besides an approve CSfC Component .
Examples [edit ]
The name shows from inside to outside the process of how the code capsule is formed in the context of Echo Protocol, used by the Software Application GoldBug Messenger. [ 6 ] GoldBug has implemented a loanblend system for authenticity and confidentiality. [ 5 ]
First layer of the encryption: The ciphertext of the master clear message is hashed, and subsequently the symmetrical keys are encrypted via the asymmetrical identify – e.g. deploying the algorithm RSA. In an intercede footstep the ciphertext, and the hash digest of the ciphertext are combined into a condensation, and packed together. It follows the set about : Encrypt-then-MAC. In order for the telephone receiver to verify that the ciphertext has not been tampered with, the compilation is computed before the ciphertext is decrypted. Second layer of encryption: Optionally it is still possible, consequently to encrypt the capsule of the first base layer in summation with an AES-256, – comparable to a normally shared, 32-character long symmetrical password. hybrid encoding is then added to multiple encoding.
Third layer of the encryption: then, this encapsulate is transmitted via a procure SSL/TLS connection to the communication partner
References [edit ]
farther interpretation [edit ]
- “Multiple encryption” in “Ritter’s Crypto Glossary and Dictionary of Technical Cryptography”
- Confidentiality through Multi-Encryption, in: Adams, David / Maier, Ann-Kathrin (2016): BIG SEVEN Study, open source crypto-messengers to be compared – or: Comprehensive Confidentiality Review & Audit of GoldBug, Encrypting E-Mail-Client & Secure Instant Messenger, Descriptions, tests and analysis reviews of 20 functions of the application GoldBug based on the essential fields and methods of evaluation of the 8 major international audit manuals for IT security investigations including 38 figures and 87 tables., URL: https://sf.net/projects/goldbug/files/bigseven-crypto-audit.pdf – English / German Language, Version 1.1, 305 pages, June 2016 (ISBN: DNB 110368003X – 2016B14779).
- A “way to combine multiple block algorithms” so that “a cryptanalyst must break both algorithms” in §15.8 of Applied Cryptography, Second Edition: Protocols, Algorithms, and Source Code in C by Bruce Schneier. Wiley Computer Publishing, John Wiley & Sons, Inc.
- S. Even and O. Goldreich, On the power of cascade ciphers, ACM Transactions on Computer Systems, vol. 3, pp. 108–116, 1985.
- M. Maurer and J. L. Massey, Cascade ciphers: The importance of being first, Journal of Cryptology, vol. 6, no. 1, pp. 55–61, 1993.