Hashing in SQL Server

Before we look into how to implement hashing in SQL Server, we need to understand the difference between hashing and encryption.

Encryption VS Hashing:

Encryption its a reversible operation i.e., you can decrypt the encrypted value with a key.
Hashing value cannot decrypted back to its original value.

HASHBYTES:

HASHBYTES function in SQL Server returns the hash value of a given input string.

this function uses following algorithms to hash the value.

1. MD2
2. MD4
3. MD5
4. SHA
5. SHA1
6. SHA2
7. SHA2_256(Applies to SQL Server 2012 to SQL Server 2014)
8. SHA2_512(Applies to SQL Server 2012 to SQL Server 2014)

this function returns type is Varbinary

syntax:

HASHBYTES ( '<algorithm>', { @input | 'input' } )

Example:

 DECLARE @HashThis nvarchar(4000);

 SET @HashThis = CONVERT(nvarchar(4000),'pranay1231232');

 SELECT HASHBYTES('SHA1', @HashThis);

 Result:

 0x52A99EAE34513AB695801F775D9F9FE2EEBBF3DB

we can use this function while storing the User Sensitive data.This is the much simple approach than TDE.