Cryptography

Cryptography (or cryptology; from Greek κρυπτός kryptós, “hidden, secret”; and γράφειν graphein, “writing”, or -λογία -logia, “study”, respectively) is the practice and study of techniques for secure communication in the presence of third parties (called adversaries). More generally, it is about constructing and analyzing protocols that block adversaries; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce.

Rbcafe » Cryptography

Securityd

Securityd

securityd — Security context daemon for Authorization and cryptographic
operations

SYNOPSIS

securityd

DESCRIPTION

securityd maintains security contexts and arbitrates cryptographic opera-
tions and Security Authorizations. Access to keychain items is routed
through securityd to enforce access controls and to keep private keys out
of user process address space. Authorization calls also communicate with
securityd to enforce rules contained in the /etc/authorization database.
All user interaction with securityd is mediated through the Security
Agent.

This command is not intended to be invoked directly.

HISTORY

securityd was first introduced in Mac OS X version 10.0 (Cheetah) as the
“Security Server” and was renamed in 10.4 (Panther).

AUTHORS

Perry Kiehtreiber

EOF

Rbcafe » Cryptography

RC4

RC4

RC4_set_key, RC4 – RC4 encryption

SYNOPSIS

#include (openssl/rc4.h)

void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);

void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
unsigned char *outdata);

DESCRIPTION

This library implements the Alleged RC4 cipher, which is described for
example in Applied Cryptography. It is believed to be compatible with
RC4[TM], a proprietary cipher of RSA Security Inc.

RC4 is a stream cipher with variable key length. Typically, 128 bit
(16 byte) keys are used for strong encryption, but shorter insecure key
sizes have been widely used due to export restrictions.

RC4 consists of a key setup phase and the actual encryption or decryp-
tion phase.

RC4_set_key() sets up the RC4_KEY key using the len bytes long key at
data.

RC4() encrypts or decrypts the len bytes of data at indata using key
and places the result at outdata. Repeated RC4() calls with the same
key yield a continuous key stream.

Since RC4 is a stream cipher (the input is XORed with a pseudo-random
key stream to produce the output), decryption uses the same function
calls as encryption.

Applications should use the higher level functions EVP_EncryptInit(3)
etc. instead of calling the RC4 functions directly.

RETURN VALUES

RC4_set_key() and RC4() do not return values.

NOTE

Certain conditions have to be observed to securely use stream ciphers.
It is not permissible to perform multiple encryptions using the same
key stream.

EOF

Página 3 de 512345
Rbcafe © 2004- | Rb Cafe 1.3 | Contacto Rbcafe | Rbcafe en Twitter | Rbcafe en Facebook | Política de privacidad