SHA-1 (Secure Hash Algorithm 1) algorithm is a widely used cryptographic hash function.
The SHA-1 hash algorithm always produces the same 160-bit hash output for the same given input. An SHA-1 hash output is composed of 40 hexadecimal characters.
SHA-1 was used for digital signatures and was a part of several widely-used security applications and protocols, including TLS and SSL.
Revision control systems such as Git, use SHA-1 to identify revisions and to ensure that the data has not changed due to accidental corruption.
Security flaws were identified in SHA-1 in 2005, and it is no longer considered as a secure.
The successful attacks have yet been reported on the SHA-2 variants, they are algorithmically similar to SHA-1.