2
Configuring Data Encryption and Integrity

This chapter describes how to configure native Oracle Net Services data encryption and integrity for Oracle Advanced Security. It contains the following topics:

• Oracle Advanced Security Encryption
• Oracle Advanced Security Data Integrity
• Diffie-Hellman Based Key Management
• Configuring Data Encryption and Integrity

Oracle Advanced Security Encryption

This section describes data encryption algorithms available in the current release of Oracle Advanced Security:

• Overview
• Advanced Encryption Standard
• DES Algorithm Support
• Triple-DES Support
• RSA RC4 Algorithm for High Speed Encryption

  Note: Prior to Release 8.1.7, Oracle Advanced Security provided three editions: Domestic, Upgrade, and Export--each with different key lengths. This release now contains a complete complement of the available encryption algorithms and key lengths, previously only available in the Domestic edition. Users deploying prior versions of the product can obtain the Domestic edition for a specific product release.

Overview

The purpose of a secure cryptosystem is to convert plaintext data into unintelligible ciphertext based on a key, in such a way that it is very hard (computationally infeasible) to convert ciphertext back into its corresponding plaintext without knowledge of the correct key. In a symmetric cryptosystem, the same key is used both for encryption and decryption of the same data. Oracle Advanced Security provides the DES, 3DES, and RC4 symmetric cryptosystems for protecting the confidentiality of Oracle Net Services traffic.

Advanced Encryption Standard

In this release, the new Federal Information Processing Standard (FIPS) encryption algorithm, Advanced Encryption Standard (AES), is supported. AES can be used by all U.S. government organizations and businesses to protect sensitive data over a network. This encryption algorithm defines three standard key lengths, which are 128-bit, 192-bit, and 256-bit. All versions operate in outer Cipher Block Chaining (CBC) mode.

DES Algorithm Support

Oracle Advanced Security provides the Data Encryption Standard (DES) algorithm. DES has been a U.S. government standard for many years and is sometimes mandated in the financial services industry. Because it has been a standard for so long, DES is deployed throughout the world for use in a wide variety of applications.

Triple-DES Support

Oracle Advanced Security supports Triple-DES encryption (3DES), which encrypts message data with three passes of the DES algorithm. 3DES provides a high degree of message security, but with a performance penalty--the magnitude of which is dependent upon on the speed of the processor performing the encryption; 3DES typically takes three times as long to encrypt a data block as compared with the standard DES algorithm.

3DES is available in two-key and three-key versions, with effective key lengths of 112-bits and 168-bits, respectively. Both versions operate in outer Cipher Block Chaining (CBC) mode.

DES40 Algorithm

The DES40 algorithm, available in every release of Oracle Advanced Security, Oracle Advanced Networking Option, and Secure Network Services, is a variant of DES in which the secret key is preprocessed to provide 40 effective key bits. It was designed to provide DES-based encryption to customers outside the U.S. and Canada at a time when the U.S. export laws were more restrictive. Now, in Oracle Advanced Security Release 2 (9.2), DES40, DES, and 3DES are all available for export. DES40 is still supported to provide backward-compatibility for international customers.

RSA RC4 Algorithm for High Speed Encryption

The RC4 algorithm, developed by RSA Data Security Inc., has become the international standard for high-speed data encryption. RC4 is a variable key-length stream cipher that operates at several times the speed of DES, making it possible to encrypt large, bulk data transfers with minimal performance consequences.

Oracle Advanced Security Release 2 (9.2) provides an RC4 implementation with 40-bit, 56-bit, 128-bit, and 256-bit key lengths. This provides backward-compatibility and strong encryption, with no material performance compromise.

Oracle Advanced Security Data Integrity

Encryption of network data provides data privacy, so that unauthorized parties are not able to view plaintext data as it passes over the network. Oracle Advanced Security also provides protection against two forms of active attack:

• Data modification attack

  This type of attack occurs when an unauthorized party intercepts data in transit, alters it, and retransmits it. For example, if a bank deposit of $100 is intercepted and the monetary amount is to $10,000, and then the higher amount is retransmitted that is a data modification attack.

• Replay attack

  This type of attack occurs when an entire set of valid data is repetitively retransmitted. For example, if a bank withdrawal of $100 is intercepted and then retransmitted ten times so the final withdrawal amount equals $10,000 then that is a replay attack.

Data Integrity Algorithms Supported

Oracle Advanced Security lets you select a keyed, sequenced implementation of the Message Digest 5 (MD5) algorithm or the Secure Hash Algorithm (SHA-1) to protect against both of these forms of attack. Both of these hash algorithms create a checksum that changes if the data is altered in any way. This protection operates independently from the encryption process--you can enable data integrity with or without enabling encryption.

Diffie-Hellman Based Key Management

The secrecy of encrypted data depends upon the existence of a secret key shared between the communicating parties. A key is a secret exclusively shared by parties on both sides of a connection. Without the key, it is extremely difficult (computationally infeasible) to decrypt an encrypted message or to alter a cryptographic-checksummed message without detection. Providing and maintaining such secret keys is referred to as key management.

Secure key distribution is difficult in a multiuser environment. Oracle Advanced Security uses the well known Diffie-Hellman key negotiation algorithm to perform secure key distribution for both encryption and data integrity.

When encryption is used to protect the security of encrypted data, keys must be changed frequently to minimize the effects of a compromised key. Accordingly, the Oracle Advanced Security key management function changes the session key with every session.

Authentication Key Fold-in

The purpose of Authentication Key Fold-in is to defeat a possible third party attack (historically called the man-in-the-middle attack) on the Diffie-Hellman key negotiation. It strengthens the session key significantly by combining a shared secret, known only to the client and the server, with the original session key negotiated by Diffie-Hellman.

The client and the server begin communicating using the session key generated by Diffie-Hellman. When the client authenticates to the server, they establish a shared secret that is only known to both parties. Oracle Advanced Security combines the shared secret and the Diffie-Hellman session key to generate a stronger session key designed to defeat a man-in-the-middle attack.

Configuring Data Encryption and Integrity

This section describes how to configure Oracle Advanced Security native Oracle Net Services encryption and integrity, and presumes the prior installation of Oracle Net Services.

The network or security administrator sets up the encryption and integrity configuration parameters. The profile on client and server systems using data encryption and integrity (sqlnet.ora file) must contain some or all of the parameters listed in this section, under the following topics:

• Activating Encryption and Integrity
• Negotiating Encryption and Integrity
• Setting the Encryption Seed
• Configuring Encryption and Integrity Parameters Using Oracle Net Manager

  See Also: Chapter 7, Configuring Secure Sockets Layer Authentication, to configure the SSL feature for encryption, integrity, and authentication

Activating Encryption and Integrity

In any network connection, it is possible for both the client and server to each support more than one encryption algorithm and more than one integrity algorithm. When a connection is made, the server selects which algorithm to use, if any, from those algorithms specified in the sqlnet.ora files.

The server searches for a match between the algorithms available on both the client and the server, and picks the first algorithm in its own list that also appears in the client list. If one side of the connection does not specify an algorithm list, all the algorithms installed on that side are acceptable. The connection fails with error message ORA-12650 if either side specifies an algorithm that is not installed.

Encryption and integrity parameters are defined by modifying a sqlnet.ora file on the clients and the servers on the network.

You can choose to configure any or all of the available Oracle Oracle Advanced Security encryption algorithms (Table 2-2), and either or both of the available integrity algorithms (Table 2-3). Only one encryption algorithm and one integrity algorithm are used for each connect session.

Negotiating Encryption and Integrity

To negotiate whether to turn on encryption or integrity, you can specify four possible values for the Oracle Advanced Security encryption and integrity configuration parameters. The four values are listed in the order of increasing security. The value REJECTED provides the minimum amount of security between client and server communications, and the value REQUIRED provides the maximum amount of network security:

• REJECTED
• ACCEPTED
• REQUESTED
• REQUIRED

The default value for each of the parameters is ACCEPTED.

REJECTED

Select this value if you do not elect to enable the security service, even if required by the other side.

In this scenario, this side of the connection specifies that the security service is not permitted. If the other side is set to REQUIRED, the connection terminates with error message ORA-12650. If the other side is set to REQUESTED, ACCEPTED, or REJECTED, the connection continues without error and without the security service enabled.

ACCEPTED

Select this value to enable the security service if required or requested by the other side.

In this scenario, this side of the connection does not require the security service, but it is enabled if the other side is set to REQUIRED or REQUESTED. If the other side is set to REQUIRED or REQUESTED, and an encryption or integrity algorithm match is found, the connection continues without error and with the security service enabled. If the other side is set to REQUIRED and no algorithm match is found, the connection terminates with error message ORA-12650.

If the other side is set to REQUESTED and no algorithm match is found, or if the other side is set to ACCEPTED or REJECTED, the connection continues without error and without the security service enabled.

REQUESTED

Select this value to enable the security service if the other side permits it.

In this scenario, this side of the connection specifies that the security service is desired but not required. The security service is enabled if the other side specifies ACCEPTED, REQUESTED, or REQUIRED. There must be a matching algorithm available on the other side--otherwise the service is not enabled. If the other side specifies REQUIRED and there is no matching algorithm, the connection fails.

REQUIRED

Select this value to enable the security service or preclude the connection.

In this scenario, this side of the connection specifies that the security service must be enabled. The connection fails if the other side specifies REJECTED or if there is no compatible algorithm on the other side.

Table 2-1 shows whether the security service is enabled, based on a combination of client and server configuration parameters. If either the server or client has specified REQUIRED, the lack of a common algorithm causes the connection to fail. Otherwise, if the service is enabled, lack of a common service algorithm results in the service being disabled.

Table 2-1 Encryption and Data Integrity Negotiation

	Client
		REJECTED	ACCEPTED	REQUESTED	REQUIRED
Server	REJECTED	OFF	OFF	OFF	Connection fails
	ACCEPTED	OFF	OFFFoot 1	ON	ON
	REQUESTED	OFF	ON	ON	ON
	REQUIRED	Connection fails	ON	ON	ON

1 This value defaults to OFF. Cryptography and data integrity are not enabled until the user changes this parameter using Oracle Net Manager or by modifying the sqlnet.ora file.

Setting the Encryption Seed

Three seeds are used to generate a random number on the client and on the server. One of the seeds is a user-defined encryption seed (sqlnet.crypto_seed=) that can be 10 to 70 characters in length--and changed at any time. The Diffie-Hellman key exchange uses the random numbers to generate unique session keys for every connect session.

Configuring Encryption and Integrity Parameters Using Oracle Net Manager

You can set up or change encryption and integrity parameter settings using Oracle Net Manager. This section describes the following topics:

• Configuring Encryption on the Client and the Server
• Configuring Integrity on the Client and the Server

  See Also: Appendix A, Data Encryption and Integrity Parameters, for valid encryption algorithms Oracle Net Manager online help, for more detailed configuration information

Configuring Encryption on the Client and the Server

To configure encryption on the client and on the server:

1. Start Oracle Net Manager:
   • On UNIX, run netmgr from $ORACLE_HOME/bin.
   • On Windows NT, choose Start > Programs > Oracle - HOME_NAME > Network Administration > Oracle Net Manager.
2. In the Navigator window, expand Local > Profile.
3. From the list in the right window pane, select Oracle Advanced Security; the Oracle Advanced Security tabbed window appears (Figure 2-1):

Figure 2-1 Oracle Advanced Security Encryption Window

Text description of the illustration asoencry.gif

• Choose the Encryption tab.
• Depending upon which system you are configuring, select CLIENT or SERVER from the pull-down list.
• From the Encryption Type list, select one of the following:
  • REQUESTED
  • REQUIRED
  • ACCEPTED
  • REJECTED
• In the Encryption Seed field, enter between 10 and 70 random characters; the encryption seed for the client should not be the same as that for the server.
• Select an encryption algorithm in the Available Methods list. Move it to the Selected Methods list by choosing the right arrow [>]. Repeat for each additional method you want to use.
• Choose File > Save Network Configuration; the sqlnet.ora file is updated.
• Repeat this procedure to configure encryption on the other system. The sqlnet.ora file on the two systems should contain the following entries:
  • On the server:

    SQLNET.ENCRYPTION_SERVER = [accepted | rejected | requested | required]
    SQLNET.ENCRYPTION_TYPES_SERVER = (valid_encryption_algorithm [,valid_
    encryption_algorithm])
    SQLNET.CRYPTO_SEED = "10-70 random characters"
    

  • On the client:

    SQLNET.ENCRYPTION_CLIENT = [accepted | rejected | requested | required]
    SQLNET.ENCRYPTION_TYPES_CLIENT = (valid_encryption_algorithm [,valid_
    encryption_algorithm])
    SQLNET.CRYPTO_SEED = "10-70 random characters"
    
    

  Valid encryption algorithms and their associated legal values are summarized by Table 2-2:

  Table 2-2 Valid Encryption Algorithms

  Algorithm Name	Legal Value
  RC4 256-bit key	RC4_256
  RC4 128-bit key	RC4_128
  RC4 56-bit key	RC4_56
  RC4 40-bit key	RC4_40
  AES 256-bit key	AES256
  AES 192-bit key	AES192
  AES 128-bit key	AES128
  3-key 3DES	3DES168
  2-key 3DES	3DES112
  DES 56-bit key	DES
  DES 40-bit key	DES40

  
  
  

  Configuring Integrity on the Client and the Server

  To configure data integrity on the client and on the server:

  1. Start Oracle Net Manager:
     • On UNIX, run netmgr from $ORACLE_HOME/bin.
     • On Windows NT, choose Start > Programs > Oracle - HOME_NAME > Network Administration > Oracle Net Manager.
  2. In the Navigator window, expand Local > Profile.
  3. From the list in the right pane, select Oracle Advanced Security; the Oracle Advanced Security tabbed window appears (Figure 2-2):

  Figure 2-2 Oracle Advanced Security Integrity Window

  

  Text description of the illustration cfig0002.gif

• Choose the Integrity tab.
• Depending upon which system you are configuring, choose the Server or Client check box.
• From the Checksum Level list, select one of the following checksum level values:
  • REQUESTED
  • REQUIRED
  • ACCEPTED
  • REJECTED
• Select an integrity algorithm in the Available Methods list. Move it to the Selected Methods list by choosing the right arrow [>]. Repeat for each additional method you want to use.
• Choose File > Save Network Configuration; the sqlnet.ora file is updated.
• Repeat this procedure to configure integrity on the other system. The sqlnet.ora file on the two systems should contain the following entries:
  • On the server:

    SQLNET.CRYPTO_CHECKSUM_SERVER = [accepted | rejected | requested | 
    required]
    SQLNET.CRYPTO_CHECKSUM_TYPES_SERVER = (valid_crypto_checksum_algorithm 
    [,valid_crypto_checksum_algorithm])
    

  • On the client:

    SQLNET.CRYPTO_CHECKSUM_CLIENT = [accepted | rejected | requested | 
    required]
    SQLNET.CRYPTO_CHECKSUM_TYPES_CLIENT = (valid_crypto_checksum_algorithm 
    [,valid_crypto_checksum_algorithm])
    
    

  Valid integrity algorithms and their associated legal values are displayed by Table 2-3:

  Table 2-3 Valid Integrity Algorithms

  Algorithm Name	Legal Values
  MD5	MD5
  SHA-1	SHA1