Adaptec 2940U - AHA Storage Controller Ultra SCSI 20 MBps Información técnica descargar pdf (Pagina 115)

Chapter 4 Securing the Enterprise 101

The disadvantage of a symmetric key algorithm is that the secret key used to

encrypt the data must be sent to whoever needs to decrypt the data. If there was a

secure channel to transmit the key, the data could be sent the same way and

encryption would be unnecessary.

The second type of algorithm is a public-private key algorithm. It relies on certain

mathematical properties to create a set of keys, such that one key can only encrypt

data and the other key can only decrypt the data. The encrypt-only key is called a

public key. The decrypt-only key is called a private key. A message encrypted

with the public key can only be decrypted by the private key.

The public key can be openly transmitted without compromising the security of

the encrypted data. Knowing the public key does not allow anyone to decrypt the

encrypted data.

Many modern encryption programs combine the two types of algorithms. A

symmetric key algorithm encrypts the data. The secret key is exchanged using a

public-private key algorithm. This provides the speed of a symmetric key

algorithm with the security of a public-private key algorithm.

RC5 is a symmetric key algorithm. The Diffie-Hellman key agreement algorithm

is a public-private key algorithm.

Understanding Government Export Restrictions

The United States government restricts the export of strong cryptography.

Encryption strength is usually defined by the size of the keys used to encrypt and

decrypt data.

Encryption products using keys greater than 56 bits are usually restricted from

export. However, larger keys can be exported for use in authentication products.

SecureICA Services comes in two versions: North American and Global. The

North American version of SecureICA Services uses a 128-bit key during user

logon. A selectable 40-, 56-, or 128-bit key is used to encrypt the remainder of the

session. The Global version uses a 128-bit key during user logon. A 56-bit key is

used to encrypt the remainder of the session.

United States export policy regarding encryption has been known to allow for

export of stronger data keys to subsidiaries of North American based financial

institutions. The export of these stronger keys must be applied for and is

controlled on a per-application basis.

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Adaptec 2940U - AHA Storage Controller Ultra SCSI 20 MBps Información técnica Pagina 115