C# use SHA1 to hash string into byte array

Question

I'm using SHA1 to encrypt some values like password. This is my code:

String passwd = Membership.GeneratePassword(10, 2);
SHA1 sha = new SHA1CryptoServiceProvider();
byte [] password = sha.ComputeHash(passwd);

But VS returns error, because passwd is a string. I have to store the password in a byte array, so is there a way to solve this?

You are using unsalted SHA1, just like LinkedIn in the past. As you might have heard, that didn't work out too well for them. Instead use bcrypt, it slows down password crackers a couple orders of magnitude and has built-in salting. — Wim Coenen
– Wim Coenen, Commented Mar 24, 2014 at 0:01

meziantou · Accepted Answer · 2014-03-23 23:51:25Z

15

String passwd = Membership.GeneratePassword(10, 2);
byte[] bytes = System.Text.Encoding.UTF8.GetBytes(passwd);
SHA1 sha = new SHA1CryptoServiceProvider();
byte [] password = sha.ComputeHash(bytes);

Note that SHA1 does not encrypt data but hash them instead. Encrypted data can be decrypted. Hash algorithms are one way.

edited Mar 23, 2014 at 23:51

answered Mar 23, 2014 at 23:32

meziantou

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2 Comments

Racil Hilan Over a year ago

Although @tvanfosson got it correctly first, +1 from me for enhancing your answer after being accepted.

Ryan Nel Over a year ago

byte[] password = new SHA1Managed().ComputeHash(Encoding.UTF8.GetBytes(input)); as a one liner.

tvanfosson · Accepted Answer · 2014-03-23 23:47:02Z

1

Use an Encoding to convert the string to a byte array

var bytes= Encoding.UTF8.GetBytes(passwd);
var password = sha.ComputeHash(bytes);

edited Mar 23, 2014 at 23:47

answered Mar 23, 2014 at 23:32

tvanfosson

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2 Comments

Racil Hilan Over a year ago

I would change the variable name to encoded, otherwise this is a bit confusing, isn't it?

Racil Hilan Over a year ago

The new name bytes is much better. And I'd go with your answer using UTF8 rather that the accepted answer with Unicode. You beat me to it, so +1 from me ;).

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