SHA1 Hash Check (XSHA1) - KB Article #2049Related Articles -- 2051, 2050, 2048, 1485
The XSHA1 command asks the server to perform a cyclic redundancy check using the SHA1 algorithm on the specified file. If the XSHA1 command is supported, the server will respond with the result of the calculation. FTP clients can use this command to verify that the file was transferred without corruption by comparing the server's response with its own calculation.
The SHA-1 algorithm operates by first breaking down the file into 512 byte blocks, then padding the last block so that it is also 512 bites in length. The algorithm then creates sixteen 32-bit words and extends them into eighty 32-bit words, then produces the final hash.