I created a plugin for NSIS. It is called HashInfo
HashInfo plugin for NSIS provides several cryptographic functions that allow you to generate hash values for a given string or file. Installer creator (NSIS based) can use one of many hash algorithms.
Name: SysInfo 2.0
License: Freeware
Min. OS: Win7
Min. NSIS: 3.0 (Win32/Win64 Unicode)
Current version of plugin (tested with NSIS 3.8) allows you to generate file or string hash using CRC/Checksums functions, Cryptographic Hash Functions and Non-cryptographic Hash Functions.
INFORMATION AND DOWNLOAD: HashInfo 2.0
More information and example usage of all supported functions can be found in demo script (HashInfoDemo.nsi) included in plugin zip package.
The plugin is based on the HashLib4Pascal library, which provides an easy-to-use interface for calculating hashes and checksums.
-Pawel