I have been playing around with the DBMS_CRYPTO package, trying to generate a lot of hashes. I want to study the distribution of hashes for different inputs using assorted hash functions. The HASH() function seemed easy enough. Just pass two parameters: the input your want to hash, plus the hash function you want it to use. Unfortunately, I ran into trouble.
The DBMS_CRTPYO package defines six hash types in its packages specification. For example, HASH_MD4. But when I tried to specify MD4 using this variable, I kept getting PL/SQL: ORA-00904: "SYS"."DBMS_CRYPTO"."HASH_MD4": invalid identifier. What was going on here? I was explicitly granted EXECUTE on the DMB_CRYPTO. I should be able to see that variable.
I searched the web and was about to give up. Just hard coded the hash function values. Then I found the answer on TalkAPEX. My problem was that I was trying to use the package variable from SQL*Plus. Not allowed. You can only get access to the package variable from PL/SQL. Aha!
So now I just wrote a procedure to run my hashing. The procedure, via definer's rights, has EXECUTE on the package. And it can access the package spec variables. Now I am good to go. Only thing left to do is feed these hashes a whole lot more inputs.
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