Portable or "traveller mode" means the encryption software can be run without installation to the system hard drive. In this mode, the software typically installs a temporary driver from the portable media. Since it is installing a driver (albeit temporarily), administrative privileges are still required.

more...

Hardware designed for a particular purpose can often achieve better performance than software implementations. And disk encryption hardware can be made more transparent to software than encryption done in software. As soon as the key has been initialized, the hardware should in principle be completely transparent to the OS and thus work with any OS.

more...

Nearly everything including the swap space and the temporary files is encrypted. Encrypting these files is important, as they can reveal important confidential data. With a software implementation, the bootstrapping code cannot be encrypted however. (For example, Bitlocker leaves an unencrypted volume to boot from, while the volume containing the operating system is fully encrypted.)

more...

A hash function that is injective — that is, maps each valid input to a different hash values — is said to be perfect. With such a function one can directly locate the desired entry in a hash table, without any additional searching.

more...

A perfect function for a given set of n keys, suitable for use in a hash table, can be found in time proportional to n, can be represented in less than 3*n bits, and can be evaluated in a constant number of operations. There are generators that will emit optimized executable code to evaluate a perfect hash for a given input set.

more...

In ordinary applictions, this advantage may be too small to offset their much higher cost. [6] However, this method can provide uniformly distributed hashes even when the keys are chosen by a malicious agent. This feature may help protect services against denial of service attacks.

more...

In computer science, geometric hashing is a method for efficiently finding two-dimensional objects represented by discrete points that have undergone an affine transformation. (Extensions exist to some other object representations and transformations.)

more...

It was finally explicitly recognized in the 19th century that secrecy of a cipher's algorithm is not a sensible or practical safeguard; in fact, it was further realized that any adequate cryptographic scheme (including ciphers) should remain secure even if the adversary fully understands the cipher algorithm itself. Secrecy of the key should alone be sufficient for a good cipher to maintain confidentiality under an attack.

more...

With the invention of polyalphabetic ciphers came more sophisticated aids such as Alberti's own cipher disk, Johannes Trithemius' tabula recta scheme, and Thomas Jefferson's multi-cylinder (reinvented independently by Bazeries around 1900). Several mechanical encryption/decryption devices were invented early in the 20th century, and many patented, among them rotor machines — famously including the Enigma machine used by the German government and military from the late 20s and during World War II.

more...

The development of digital computers and electronics after WWII made possible much more complex ciphers. Furthermore, computers allowed for the encryption of any kind of data representable within computers in any binary format, unlike classical ciphers which only encrypted written language texts.

more...

Symmetric-key cryptography refers to encryption methods in which both the sender and receiver share the same key (or, less commonly, in which their keys are different, but related in an easily computable way). This was the only kind of encryption publicly known until June 1976.

more...

A cryptographic system is any computer system that involves cryptography. Such systems include for instance, a system for secure electronic mail which might include methods for digital signatures, cryptographic hash functions, key management techniques, and so on. Cryptographic systems are made up of cryptographic primitives, and are usually rather complex.

more...

Typically, a cryptosystem consists of three algorithms: one for key generation, one for encryption, and one for decryption. The term cipher (sometimes cypher) is often used to refer to a pair of algorithms, one for encryption and one for decryption. Therefore, the term "cryptosystem" is most often used when the key generation algorithm is important.

more...

Anonymous Internet Banking is the name given to the proposed use of strong financial cryptography to make electronic bank secrecy (or more precisely pseudonymous banking) possible. The bank issues currency in the form of electronic tokens that can be converted on presentation to the bank to some other currency.

more...

Anonymous internet banking depends on the mathematics of public key cryptography and blind signature algorithms. In this simple example we have Alice and Bob and a banker. The banker generates an RSA public key with modulus n = PQ, where P and Q are large primes. As described in RSA operation, the bank also generates public key exponent e and private key exponent d.

more...

Events such as the GURPS Cyberpunk raid lent weight to the idea that private individuals needed to take steps themselves to protect their privacy. In its heyday, the list discussed the public policy issues related to cryptography, as well as more practical nuts-and-bolts mathematical, computational, technological, and cryptographic matters themselves.

more...

However, if the IP source address is false, there will be no easy way to trace the originating node (and so the originating entity for the packet). In addition, all standards-based email messages contain defined fields in their headers in which the source and transmitting entities (and Internet nodes as well) are required to be included. However, since most users of email do not have very much technical expertise, the full headers are usually suppressed by mail reading software.

more...

Symmetric ciphers have historically been susceptible to known-plaintext attacks, chosen plaintext attacks, differential cryptanalysis and linear cryptanalysis. Careful construction of the functions for each round can greatly reduce the chances of a successful attack.

more...

The Data Encryption Standard (DES) is a block cipher (a form of shared secret encryption) that was selected by the National Bureau of Standards as an official Federal Information Processing Standard (FIPS) for the United States in 1976 and which has subsequently enjoyed widespread use internationally.

more...

The algorithm's overall structure is shown in Figure 1: there are 16 identical stages of processing, termed rounds. There is also an initial and final permutation, termed IP and FP, which are inverses (IP "undoes" the action of FP, and vice versa). IP and FP have almost no cryptographic significance, but were apparently included in order to facilitate loading blocks in and out of mid-1970s hardware, as well as to make DES run slower in software.

more...