S-HTTP (Secure Hypertext Transfer Protocol)

is one of the two methods to secure Internet data. This extension to HTTP provides security features. It manages exchange of data encrypting keys and encryption. It uses systems such as RSA, KERBEROS, DES, IDEA, RC2. It operates at the application layer. The other method is SSL.

SAFER (Secure Fast Encryption Routine)

is a block cipher developed by MASSEY. In the initial version, the block size is of 64 bits. The key is 64 bit large. The number of rounds is in the range 0 to 10. It is recommended to have at least 6 rounds.


is a fraudulent business scheme. It often refers to farud using SPAMs. The best representative categories is the Nigerian SPAM where a supposed dignitary proposes you to serve as an intermediary for an important fund transfer.

SCSSI (Service Centrale de la Sécurité des Systèmes d’Informations)

was the French organization that deals with all the cryptographic algorithms. Its authorization is mandatory to cipher with a key longer than 40-bit.  The new name is DCSSI

SEAL (Software optimized Encryption Algorithm)

is a fast stream cipher for 32 bit machines.

Secret key cryptography

(also called symmetric cryptography): In this type of cryptography, the sender uses a secret key to encrypt the message. The receiver uses the same key to decrypt the message.

Secret Sharing Schemes

are a way to distribute a secret to different persons so that certain subsets of these persons can together recover the secret. The general model is called m-out-of-n scheme or (m, n) threshold scheme with integers 1 ≤ m ≤ n.  There is a sender, or dealer, and n participants. The sender divides the secret in n parts called shares or shadows. Any part of m shares can put together the secret whereas m-1 parts reveal no information about the secret.
To illustrate we provide the basic 2-out-of-3 scheme. The secret is a value defined by the intersection of a line with the abscise axis. The shares are three distinct points of belonging to the line. With two points, it is possible to find the intersection point. With one point, different from the secret point, it is not possible to find the secret.
The most renown secret sharing schemes are SHAMIR and BLAKLEY’s ones.

Secure Electronic Transaction

is a protocol developed by VISA International and Master Card for secure bank card transaction over open networks. It uses DES for encryption, and RSA for authentication and digital signatures.

Secure Socket Layer

is a protocol developed by NETSCAPE to provide security and privacy over Internet. The protocol supports server and client authentication. This session layer protocol operates at the transport layer on top of TCP/IP. The current version, 3.0, is estimated to be sure. It is widely in use on Internet.

Secure Hypertext Transfer Protocol

see S-HTTP

Semantic attack

is a category of attacks that compromises the truth of information and the integrity of sources. This type of attacks is very often used on the mail when spreading rumors for instance to push up or down stakes of companies. Web page defacements or Hoaxes are typical semantic attacks.


see Secure Electronic Transaction

SHA (Secure Hash Algorithm)

is a hash function developed by NIST. The input message must be at maximum 264-bit long. It produces a 160-bit result. It is slower than MD5 but more secure against brute force collision attack and inversion attack.

In 2007, the first attack generating collisions was disclosed.

Shrinking Generator

is a high-speed stream cipher based on the outputs of two LSFRs.


is a mean to insure the authenticity of a document. Hand written signature serves for written document. Digital signatures are used for digital document or information.

Single Sign On

is a procedure that allows to securely present only once his password for a full session in order to sign on applications requiring their own password presentation.
In simple words, when successfully logging on, you will never have to present a password although the level of security remains high. SSO allows the user to use one unique password for all the applications of the enterprise.


is a block cipher using a 80-bit ke. Until June 1998, it was classified by the US government. SKIPJACK was designed in order to prevent software implementation. It was in the chip CLIPPER. Highly questioned by the community.

S/MIME (Secure MIME)

is a protocol that adds digital signatures and encryption to MIME messages on Internet.

Social engineering

encompasses methods based on social interaction a hacker uses to get illegal access to an asset. Social engineering uses many methods, including online, telephone and even physically impersonating an individual.  A typical example is using an attractive subject for a mail for user to open it to launch a virus (I love you, Kurnikova, …)


means unsollicited electronic message either for advertising means or for frauding.


is a class of attacks in which commands from an outsider computer are disguised as if they are coming from another, friendlier computer.


is any software which employs a user’s Internet connection in the background (the so-called “backchannel”) without their knowledge or explicit permission. A spyware may be a hacker tool, or also a commercial tool. The versions of Real Networks software that reported the selections of user were commercial spywares. Many tools, such as Pest Patrol, Ad Aware, are able to detect spywares on PC.


see Secure Socket Layer


see Single Sign On

Station To Station

See Authenticated Diffie Hellman Agreement.


is the art of technique allowing to conceal the existence of a message within other messages so that potential monitors do not even know that a message is being sent. It comes from the ancient Greek words steganw (to covert) and grafein (to write) and can be translated as “covert writing”. B. Pfitzmann defined the steganography general scheme  as follows:

Important features of an information hiding technique are its capacity (payload of the embedded media compared to the payload of the covert media), its imperceptibility (to human visual or audible system if the covert media is an image or a sound, to computer in the example of viruses hidden in executable files) and its robustness (the embedded media is still detectable after the manipulation of the active warden).

Stream Cipher

is a symmetric encryption algorithm. It is faster than a block cipher. It operates on smaller units of plain text such as bits. The same block of plain text encrypted with the same key produces the same cipher text with block ciphers. It is not the case with stream ciphers.

Strong Primes

are prime numbers with properties that make the product of two of them hard to factory by specific factoring methods.

Symmetric cryptography

See Secret key cryptography

Leave a Reply

Your email address will not be published. Required fields are marked *