DESEncrypt Procedure

The DESEncrypt procedure generates the encrypted form of the input data. An example of the DESEncrypt procedure appears at the end of this chapter.

The DES algorithm encrypts data in 64-bit blocks using a 56-bit key. The DES algorithm throws away 8 bits of the supplied key (the particular bits which are thrown away is beyond the scope of this documentation). However, developers using the algorithm must supply a 64-bit key or the package will raise an error.

Parameters

Table 30-1 and Table 30-2 list the parameters for the DESEncrypt syntax, their modes, types, and descriptions.

Table 30-1 DESEncrypt parameters for raw data

Parameter Name	Mode	Type	Description
input	IN	RAW	data to be encrypted
key	IN	RAW	encryption key
encrypted_data	OUT	RAW	encrypted data

Table 30-2 DESEncrypt parameters for string data

Parameter Name	Mode	Type	Description
input_string	IN	VARCHAR2	string to be encrypted
key_string	IN	VARCHAR2	encryption key string
encrypted_string	OUT	VARCHAR2	encrypted string

If the input data or key given to the PL/SQL DESEncrypt procedure is empty, then the procedure raises the error ORA-28231 "Invalid input to Obfuscation toolkit".

If the input data given to the DESEncrypt procedure is not a multiple of 8 bytes, the procedure raises the error ORA-28232 "Invalid input size for Obfuscation toolkit".

If the user tries to double encrypt data using the DESEncrypt procedure, then the procedure raises the error ORA-28233 "Double encryption not supported".

If the key length is missing or is less than 8 bytes, then the procedure raises the error ORA-28234 "Key length too short." Note that if larger keys are used, extra bytes are ignored. So a 9-byte key will not generate an exception.

Restrictions

The DESEncryption procedure has two restrictions. The first is that the DES key length for encryption is fixed at 56 bits; you cannot alter this key length.

The second is that you cannot execute multiple passes of encryption. That is, you cannot re-encrypt previously encrypted data by calling the function twice.

Note: Both the key length limitation and the prevention of multiple encryption passes are requirements of US regulations governing the export of cryptographic products.