I have a method used to generate a hash:
public static string GetMD5Hash(string input)
{
System.Security.Cryptography.MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();
byte[] bs = System.Text.Encoding.UTF8.GetBytes(input);
bs = x.ComputeHash(bs);
System.Text.StringBuilder s = new System.Text.StringBuilder();
foreach (byte b in bs)
{
s.Append(b.ToString("x2").ToLower());
}
return s.ToString();
}
I then save that hash in a varchar(255) column. Knowing what the original input string was, would it be possible to to arrive at the same hash value stored in the varchar(255) column, using sql (2005)??
I have tried like crazy using different data types, conversions and the hashbytes() function, but have not been able to get close.
Example of my failed attempt :(
select convert(varchar, hashbytes('MD5', convert(varbinary(200), '<censored>',0)))
A Hash Table in C/C++ (Associative array) is a data structure that maps keys to values. This uses a hash function to compute indexes for a key. Based on the Hash Table index, we can store the value at the appropriate location.
A fast hash map/hash table (whatever you want to call it) for the C programming language. It can associate a key with a pointer or integer value in O(1) time.
There is no hashtable in the standard C library because either: no-one has submitted a proposal to the working group; or. the working group has deemed it unnecessary.
from #c with "bleepbloop" : 04d3f95947702213e23730a0e8fac6c3
Then
select convert(varchar(32), hashbytes('MD5', 'bleepbloop'), 2)
>> 04D3F95947702213E23730A0E8FAC6C3
Or You could just store & compare as binary.
The problem here is that x2
is getting the hex encoding of the data, where-as convert
is getting your server's configured decoding of the bytes (which isn't really valid, since that data is not text-based). Very different things. If you keep as varbinary and compare to a byte[]
you should be fine.
If you are using SQL Server 2008, you can also use:
select convert(varchar(32), hashbytes('MD5', convert(varbinary(200),
'<censored>',0)), 2)
to get the hex-encoded version (you can use 1
instead of 2
to get a leading 0x
)
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