I recently needed to implement RSA cryptography in Delphi, sticking to a few requirements of my own choosing:

1. The library used should be free

2. The library license should be permissive enough that I can use the library in a commercial application

3. The library should have as few extra files to include as possible

I looked initially at LockBox, but it came with a multitude of files to either copy to my source folder or include in my library path. I don't want other developers in my team to have to add yet more third party libraries, so I gave this a miss. Additionally, the documentation wasn't great and finding example online was quite tricky.

I then tried PGPCrypt, but could only find a version of that for Lazarus, the free Delphi compiler.

Next was the TMS Cryptography pack, but this isn't free, so again a non-starter.

Then I thought about OpenSSL. We already use OpenSSL as a DLL for a different, but related, purpose so the file is already present in our source and program folder. What we don't have are function headers as we're calling the DLL functions by importing them directly (we only use three at present), but RSA is more complicated and uses a particular structure that would need replicating in Delphi. I thought this might mean OpenSSL was also a non-starter, but after much searching online I came across the Delphi-OpenSSL project at https://github.com/UniGe/delphiopenssl/ which consists really of only three .pas files, only one of which is necessary for what I'm trying to implement: RSA encryption and decryption. For this purpose I need use only the LibEAY32.pas file coupled with the LibEAY32.dll file. We're using version 1.0.2 of this, and the Delphi-OpenSSL project is compatible with that. Great!

I needed to make a few minor changes, as despite the programmers' best efforts it seemed confused about the difference between Char and AnsiChar in Delphi 2009, but the changes were minimal and consisted, almost entirely, of me replacing references to PChar or PCharacter with PAnsiChar.

The next challenge was to see if I could use an existing key to encrypt a file.

I added my modulus, public exponent and private exponent (not needed for encryption) as Base64 encoded string constants and used:

_rsa = RSA_New();

to create a new RSA structure to populate with the key information. This actually returns a pointer to an RSA object, so it needs both dereferencing and casting when used. The properties we're interested in are the modulus, n; the public exponent, e; and the private exponent, d (when decrypting, later).

These properties take the form of BigNum objects as they can be sometimes thousands of bits long. The BigNums need to be created before being used:

RSA(_rsa^).n := BN_New();
RSA(_rsa^).e := BN_New();

The Base64 values were then decoded and altered, one byte at a time, to hex using IntToHex (which returns a string) and then BN_HexToBN was used to set the RSA record's properties accordingly:


BN_HexToBN(RSA(_rsa^).n, ansistring(public_modulus));
BN_HexToBN(RSA(_rsa^).e, ansistring(public_exponent));


The input string can then be encrypted by calling:

enc_in := SysUtils.TEncoding.ASCII.GetBytes(string(input_text));

to get the string character values as a byte array, followed by:

RSA_Public_Encrypt(length(enc_in),PAnsiChar(enc_in), PAnsiChar(@textout),_rsa,RSA_PKCS1_PADDING);

to do the actual encryption. The output cypher text is held in textout. This will look like garbage but can be converted to a Base64 string for convenient storage.

And that's it.

Two caveats:

I had to add an extra property to the RSA record to match the version of OpenSSL we're using. This was:

engine: pointer; 

below the meth property.

And I had to initialise the SSL library by calling:

SSLEay_version(_SSLEAY_VERSION);

before making any calls to encryption or decryption routines. There's probably a better way to do this, but this did the trick.

I put this information here in the hope that it helps someone else who struggled as much as I did to implement this!

Today I completed my first challenge on Say Something In Welsh, which was to say a sentence constructed around each of the below words and phrases out loud within five minutes:

I want to
I'm going to
I can't
I need
What
But
I wanted
I've just started
I've forgotten
I was trying
...that I need...
I must
I would like to

no doubt those passing me thought I was a little odd, as I sat in my car in McDonald's car park talking, mostly, about how I need to feed the dog, eat a burger or go to the pub!

Still, I feel I've achieved something. I shall wear my pink badge with pride (well, my avatar on the forum will).

The next challenge is to record the sentences and post them for the world to see. Oooeeer!

Five months or so ago, I embarked on a language learning adventure. I decided to learn Welsh. I'm not Welsh, I don't live in Wales, and I'm not planning on moving to Wales any time soon. Not that Wales isn't a lovely place, but it's not currently part of my plans.

It started as a bit of a joke. My partner's daughter, Lulu, started at Cardiff University last autumn and has the option of taking free Welsh lessons as part of her course. She scoffed at the idea, "Everyone speaks English! Why would I need to learn Welsh?". I explained that it might not be necessary, but why not take advantage of a free route to learning another language, but to no avail.

I can't say I blame her; I'd always been dismissive of the minority languages of the United Kingdom: Welsh, Gaelic, Cornish. They're dying out, aren't they?

Well, yes and no. Cornish is down to just a few scores of speakers and Gaelic has only around 50,000. But Welsh is a bit different. Welsh is still used. And it's still used by young people, for some of whom it's both a native and a first language. In fact, following a decline in the first half of the 20th century, Welsh is actually thriving somewhat, with the aim set by the Welsh Assembly to get one million speakers by 2050.

So back to Lulu. Every time we spoke following her enrollment at university I would ask her "Learning Welsh yet?" and every time she'd say "no", getting increasingly fed up with me asking, until one day she snapped, "If you love Welsh so much, why don't you bloody learn it?!". I saw that as a challenge and tentatively started looking for resources online.

My first port of call was Babbel, which I'd used in an aborted attempt to learn Spanish before, but alas they offer no Welsh course. I then found some excellent YouTube videos from WelshPlus, but they focussed entirely on familiarisation with the Welsh alphabet and pronunciation. Then someone suggested DuoLingo. DuoLingo courses are run by volunteers, who use the DuoLingo platform tools to create content to teach others. And DuoLingo has a Welsh course. And it's free. I signed up and dived into Cymraeg!

So, I'm now a Welsh learner, or Dysgwr Cymraeg, and I intend to chart my Welsh odyssey here.