SSL uses a cryptographic hash function similar to checksum, to ensure data integrity in transit and detect accidental alterations in the data. The hash is encrypted with a secret key with the private key belonging to the sender encrypts the hash for the digital signature of the message.

When secret key information is included with the cryptographic hash, the resulting hash is known as a Keyed-Hashing Message Authentication Code (HMAC) value. HMAC is a mechanism for message authentication that uses cryptographic hash functions. Use this mechanism with any iterative cryptographic hash function, in combination with a secret shared key.

In the product, both well known one-way hash algorithms, MD5 and SHA-1, are supported. One-way hash is an algorithm that converts processing data into a string of bits known as a hash value or a message digest. One-way means that it is extremely difficult to turn the fixed string back into the original data. The following explanation includes both the MD5 and SHA-1 one-way hash algorithms...

Refer to the Transport Layer Security (TLS) specification at for further information.