What is the purpose of using generateDigest method of Crypto Class?

Hi Suraj

generateDigest(algorithmName, input)
Computes a secure, one-way hash digest based on the supplied input string and algorithm name.
Signature
public static Blob generateDigest(String algorithmName, Blob input)
Parameters
algorithmName
Type: String
Valid values for algorithmName are:

MD5
SHA1
SHA-256
SHA-512
input
Type: Blob
Return Value
Type: Blob
Example
Blob targetBlob = Blob.valueOf(‘ExampleMD5String’);
Blob hash = Crypto.generateDigest(‘MD5’, targetBlob);

Hope it may help