Save byte array in sql server

Question

Am looking to use an approach in saving passwords that requires using byte array as in this post

So which data type should i use in sql server to save byte array? and how can i pass and retrieve the byte array using SqlCommand?

Achieve

Answer 1

If it's always going to be the same length, then binary(length) would be suitable. If it's going to vary in length, use varbinary(maxlength).

binary and varbinary.

And, as @p.s.w.g says, you pass it from code by placing it into a suitable parameter.

Thistledown

Thanks for the answer! Really helped me a lot. I got confused at the beginning and think is important to remark that varbinary(maxlength) doesn't refer to varbinary(max). 'maxlength' refers to the maximum posible length for your hashed passwords – Tade

Answer 2

Just use a byte[] the same way you would any other parameter, specifying SqlDbType.Binary as the parameter type. Here a sample in C#

// Generate your password hash some way
byte[] passwordHash = new byte[] { 0x0, 0x1, 0x2 ... };

...

command.Parameters.Add("@passwordHash", SqlDbType.Binary);
command.Parameters["@passwordHash"].Value = passwordHash;

Or if you prefer VB.NET

' Generate your password hash some way
Dim passwordHash As Byte() = New Byte() { &H0, &H1, &H2 ... }

...

command.Parameters.Add("@passwordHash", SqlDbType.Binary)
command.Parameters("@passwordHash").Value = passwordHash

Torsk

is it fine to use binary sql data type? as i googled some people telling its use for big binary files like images, do you agree with that? – Achieve

@user2155873 Use VARBINARY(MAX) for files which are somewhat large or are of varying length. For password hashes use BINARY(32) (or however long your hash is). – Torsk

@user2155873 - given that you can declare a binary(5), that allocates storage for 5 bytes, would you say that that was only suitable for storing a big file? – Thistledown

Answer 3

I'd recommend using nvarchar(45) and Base64 your 32 bytes into a string. This is the standard way of saving a hash.

Alternatively you could do nvarchar(64) and store it as a hex string.

Ozone

I've read the Microsoft docs about this subject and never saw the recommendation to convert the hash to Base64. Anyway, why not saving the hash as a byte array? – Baker