Oracle9i Supplied PL/SQL Packages and Types Reference Release 1 (9.0.1) Part Number A89852-02 |
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DBMS_OBFUSCATION_TOOLKIT , 5 of 5
The purpose of the DES3Decrypt procedure is to generate the decrypted form of the input data. An example of the DES3Decrypt procedure appears at the end of this chapter.
Table 30-7 and Table 30-8 list the parameters for the DES3Decrypt syntax, their modes, types, and descriptions.
If the input data or key given to the DES3Decrypt procedure is empty, then the procedure raises the error ORA-28231 "Invalid input to Obfuscation toolkit".
If the input data given to the DES3Decrypt procedure is not a multiple of 8 bytes, the procedure raises the error ORA-28232 "Invalid input size for Obfuscation toolkit". ORA-28233 is NOT applicable for the DES3Decrypt function.
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.
If an incorrect value is specified for the WHICH parameter, ORA-28236 "Invalid Triple DES mode" is generated. Only the values 0 (TwoKeyMode) and 1 (ThreeKeyMode) are valid.
As stated above, a developer must supply a single key of either 128 bits for a 2-key implementation (of which only 112 are used), or a single key of 192 bits for a 3-key implementation (of which 168 bits are used). Oracle automatically truncates the supplied key into 56-bit lengths for decryption. This key length is fixed and cannot be altered.
Following is a sample PL/SQL program for your reference. Segments of the code are numbered and contain narrative text explaining portions of the code.
DECLARE input_string VARCHAR2(16) := 'tigertigertigert'; raw_input RAW(128) := UTL_RAW.CAST_TO_RAW(input_string); key_string VARCHAR2(16) := 'scottscottscotts'; raw_key RAW(128) := UTL_RAW.CAST_TO_RAW(key_string); encrypted_raw RAW(2048); encrypted_string VARCHAR2(2048); decrypted_raw RAW(2048); decrypted_string VARCHAR2(2048); error_in_input_buffer_length EXCEPTION; PRAGMA EXCEPTION_INIT(error_in_input_buffer_length, -28232); INPUT_BUFFER_LENGTH_ERR_MSG VARCHAR2(100) := '*** DES INPUT BUFFER NOT A MULTIPLE OF 8 BYTES - IGNORING EXCEPTION ***'; double_encrypt_not_permitted EXCEPTION; PRAGMA EXCEPTION_INIT(double_encrypt_not_permitted, -28233); DOUBLE_ENCRYPTION_ERR_MSG VARCHAR2(100) := '*** CANNOT DOUBLE ENCRYPT DATA - IGNORING EXCEPTION ***'; -- 1. Begin testing raw data encryption and decryption BEGIN dbms_output.put_line('> ========= BEGIN TEST RAW DATA ========='); dbms_output.put_line('> Raw input : ' || UTL_RAW.CAST_TO_VARCHAR2(raw_input)); BEGIN dbms_obfuscation_toolkit.DES3Encrypt(input => raw_input, key => raw_key, encrypted_data => encrypted_raw ); dbms_output.put_line('> encrypted hex value : ' || rawtohex(encrypted_raw)); dbms_obfuscation_toolkit.DES3Decrypt(input => encrypted_raw, key => raw_key, decrypted_data => decrypted_raw); dbms_output.put_line('> Decrypted raw output : ' || UTL_RAW.CAST_TO_VARCHAR2(decrypted_raw)); dbms_output.put_line('> '); if UTL_RAW.CAST_TO_VARCHAR2(raw_input) = UTL_RAW.CAST_TO_VARCHAR2(decrypted_raw) THEN dbms_output.put_line('> Raw DES3 Encyption and Decryption successful'); END if; EXCEPTION WHEN error_in_input_buffer_length THEN dbms_output.put_line('> ' || INPUT_BUFFER_LENGTH_ERR_MSG); END; dbms_output.put_line('> '); END; -- 2. Begin testing string data encryption and decryption dbms_output.put_line('> ========= BEGIN TEST STRING DATA ========='); BEGIN dbms_output.put_line('> input string : ' || input_string); dbms_obfuscation_toolkit.DES3Encrypt( input_string => input_string, key_string => key_string, encrypted_string => encrypted_string ); dbms_output.put_line('> encrypted hex value : ' || rawtohex(UTL_RAW.CAST_TO_RAW(encrypted_string))); dbms_obfuscation_toolkit.DES3Decrypt( input_string => encrypted_string, key_string => key_string, decrypted_string => decrypted_string ); dbms_output.put_line('> decrypted string output : ' || decrypted_string); if input_string = decrypted_string THEN dbms_output.put_line('> String DES3 Encyption and Decryption successful'); END if; EXCEPTION WHEN error_in_input_buffer_length THEN dbms_output.put_line(' ' || INPUT_BUFFER_LENGTH_ERR_MSG); END; dbms_output.put_line('> '); END;
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