I'm looking for a Delphi implementation of an asymmetric encryption algorithm without any dependencies on external DLLs. Is there any available?
My goal is to encrypt/decrypt a string (or array of bytes) using a public/private key pair.
SecureBlackBox from Eldos offers a native, comprehensive solution - including certificate management and access to external crypto devices (i.e. USB tokens)
LockBox is now improved. It allows long keys for RSA, AES cipher and is in active development. It is free, Open Source and 100% native code with no DLLs.
You can try Lockbox - http://sourceforge.net/projects/tplockbox/. It's free and includes RSA among others (Blowfish, MD5, SHA-1, DES, triple-DES, Rijndael, & digital signing of messages).
It comes complete with a good RSA example that demonstrates how to generate your public/private keys and how to actually encrypt and decrypt data using the keys.
I'm currently using it with Delphi 2010.
I realize that the original question stated "no external DLLs" but in the absence of an acceptable answer maybe you should take a look at the OpenSSL DLLs along with this Delphi link which contains an import unit for the library and some good examples on how to use it, including RSA encryption.
I have tinkered with this and got it working pretty well. There are some changes required to make it work with unicode Delphi - but these are mostly to do with changing PChar to PAnsiChar or PBytes.
Simple Delphi wrappers now allow me to sign/verify/encrypt sym or asym and use SSL. And let's be honest - the distribution of the OpenSSL DLLs is a lot more straightforward than some of the Microsoft offerings. Plus it's free and well maintained.
Take a look at the FGInt package on this site: http://submanifold.be/
If you can stomach using Windows services, there is the Crypto API: http://msdn.microsoft.com/en-us/library/aa380255(v=VS.85).aspx
If you are targeting Vista and up, there is the new Cryptography API: Next Generation. This also supports Elliptic Curve crypto: http://msdn.microsoft.com/en-us/library/aa376210(VS.85).aspx
Another very good fairly complete package is the Delphi Encryption Compendium (DEC) 5.2. You can download (Free with source) from http://www.torry.net/pages.php?id=519#939342.
来源：https://stackoverflow.com/questions/2998885/delphi-asymmetric-encryption