Free digital signature library in Delphi

Are there any free libraries that implement digital signature? I need it to work in Delphi 2010 and to be portable. By portable I mean that the library implements the actual algorithms, rather than uses Windows API.

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TurboPower LockBox doesn't work for me: here's an expalantion.

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OpenSSL should work. It's free and runs on many different platforms. It isn't a "Delphi" library but rather just an API, but it could be called from a Delphi application.

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You've got a free and fast implementation available at http://sourceforge.net/projects/openstrsecii

I'm not sure it will work as is with Delphi 2010...

OpenSSL is a great project, and you've got a Delphi use at http://www.ararat.cz/synapse/doku.php/public:howto:sslplugin

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Not exactly free, but signing functions of our SecureBlackbox product need just any license for any package, and prices for some packages are below $100.

Note, that for this price you get quite extensive functionality that covers PKCS#1 and PKCS#7 signing and encryption using RSA, DSA (signing only) and Elliptic Curves, as well as symmetric encryption, extensive certificate support and much more.

Alternatively you can use interface to OpenSSL, which also offers wide range of functions and is free. However, it's API is far from easy to understand, and as with any free software, support is questionable.