Network Encryption from Client to Server on Oracle Database connections.

For symmetric cryptsystem  , the same key is used for encryption and decryption .Oracle has a solution to encrypt data on wire.
In order to make secure data transmission from client to server we can make some configuration in sqlnet.ora file.

First we look at network encryption from client to server. For this reason ; the easiest way is to change the sqlnet.ora at client side.

Below you can see some definitions in sqlnet.ora file at client side. Simply client requests to server for secure transmission. If server Acccepts it ; network encryption starts automaticly.

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SQLNETSQLNET.ENCRYPTION_CLIENT =   Requested.
ENCRYPTION_TYPES_CLIENT = ( AES128 )
SQLNET.CRYPTO_CHECKSUM_CLIENT =   Requested
SQLNET.CRYPTO_CHECKSUM_TYPES_CLIENT = (SHA1)

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at this example ; we assume  that there is no configuration about data encryption at server side.
It means that default value for

SQLNET.ENCRYPTION_SERVER =   Accepted

If there is a configuration at server side; like this

SQLNET.ENCRYPTION_SERVER =   Rejected

You can not start data encryption between client and server.   Because your  configuration is in Requested mode and you can create connection without encryption 

In order to check data encrption we can open trace files with the following configuration in sqlnet.ora file at client side

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TRACE_LEVEL_CLIENT = 10
TRACE_DIRECTORY_CLIENT =  C:\Users\u003475\Oracle\oradiag_u003475\diag\clients\user_u003475\host_389884333_11\trace

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After changing sqlnet.ora file look at the trace files and search for  "encryption is active"  words. 
If you find  these words at trace file. It means that you succesfuly started a secure connection between client and Server.

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the inside of trace file

2014-07-03 15:08:21.586127 : nau_adi:exit

2014-07-03 15:08:21.586146 : na_tns: authentication is not active

2014-07-03 15:08:21.586166 : na_tns: encryption is active, using RC4_128

2014-07-03 15:08:21.586186 : na_tns: crypto-checksumming is not active

2014-07-03 15:08:21.586205 : na_tns:exit

2014-07-03 15:08:21.586224 : na_coco:exit

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