SHA-1 hashing

SHA-1 hashes are 160 bits or 20 bytes long. It comprises of hexadecimal numbers 40 digits long. The message digest is similar to the Rivest design for MD4 MD5. Take 5 blocks of 32 bits each, unsigned and in Big-Indian. Then do a preprocessing to the message. Append the bit 1 to the message. Append a padding of upto 512 bits so that the message aligns with 448. Append the legneth of the message as an unsigned number. Then do the processing on successive 512 bit chunks. For each chink, break the chunk into sizteen 32bit big endian words. Initializes the hash value for this chunk as h0, h1, h2, h3 and h4. Extend the sixteen 32 bit words into eighty 32 bit words this way: for each of the 16 to 79 th word, XOR the word that appears 3, 8, 14, and 16 words earlier and then leftrotate by 1. Initialize the hash value for this chunk as set of 5. In the main loop for i from 0 to 7, for each of the four equal ranges, apply the and and the or to the chunks in a predefined manner specified differently for each range. Then recompute the hash values for the chunks by exchanging them and re-assinging the first and left rotating the third by 30. At the end of the look, recompute the chunk's hash to the result so far. The final hash value is the appending of each of these chunks.
.Net Library packages this up with ComputeHash method:
A hash can be computed like this:
            var bytesToSign = Encoding.UTF8.GetBytes(content);
            HMAC hmacSha256 = new HMACSHA256(secretKeyBytes);
            byte[] hashBytes = hmacSha256.ComputeHash(bytesToSign);
            return Convert.ToBase64String(hashBytes);