Today, we will explain in a concise manner what is SHA1? SHA1 stands for Secure Hash Algorithm 1. It is a cryptographic has function which was designed by United States National Security Agency. SHA1 algorithm generates a 160-bit hash value which is equivalent to 20 bytes. This SHA1 hash value is also known as message digest. The SHA1 message digest is a 40 digits long hexadecimal number. This online SHA1 generator or SHA1 encryption tool will help you in generating SHA1 message digest for any of the given string.