digest algorithm</a>. Many tools are available to calculate these sums. For example, you can use <a href="https://www.openssl.org/" target="_blank">OpenSSL</a>:
```
-$ openssl md5 < file
+$ openssl md5 < file
```
Platform-specific applications are also common, such as `md5sum` on linux:
With GnuPG:
```
-$ gpg --print-md MD5 [fileName] > [fileName].md5
+$ gpg --print-md MD5 [fileName] > [fileName].md5
```
Like <a href="#md5">MD5</a>, <a href="http://www.ietf.org/rfc/rfc3174.txt">SHA</a> is a <a href="#message-digest">message digest</a> algorithm. Using GnuPG, you can create a SHA1 signature as follows:
```
- $ gpg --print-md SHA1 [fileName] > [fileName].sha1
+ $ gpg --print-md SHA1 [fileName] > [fileName].sha1
```
**Avoid** further use of <a href="#sha1">SHA-1</a>. `SHA256` and `SHA512` use the same `SHA` algorithm family with longer hash