CODEWITHSUNDEEP
delphicryptographyopenssl
M Schenkel
M Schenkel

Reputation: 6364

Reading Private Key in PEM format with LockBox

I have to digitally sign a string using the SHA-1 algorithm with RSA using PKCS#1 padding. I have downloaded Turbo Power Lockbox.

The private key I have is in PEM format and was created using openssl:

openssl req -x509 -nodes -days 365 -newkey rsa:1024 -sha1 -subj 
    "/C=US/ST=CA/L=Mountain View/CN=www.mycompany.com" 
    -keyout  myrsakey.pem -out c:\temp\myrsacert.pem

Here is what it looks like:

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

If I am not mistaken, the component I want to use is TLbRSAKey. So I have tried to create key object and read it from file:

var
  mPrivateKey: TLbRSAKey;
begin
  mPrivateKey := TLbRSAKey.Create(aks1024);
  mPrivateKey.LoadFromFile('C:\temp\myrsakey.pem');

On the LoadFromFile I get a "Invalid RSA Key" error. What am I doing wrong? Does Lockbox support keys in PEM format? None of the examples illustrate; everything seems to be in ASN format

Upvotes: 2

Views: 3620

Answers (1)

jheddings
jheddings

Reputation: 27573

I am not a delphi programmer, but I thought I'd try to provide some pointers.

First, make sure you generate a new private key for your real application. Now that you've shared your private key with us, we wouldn't want any open security holes out there.

Secondly, the ASN.1 format is generated using the DER output from OpenSSL. The PEM format is just the base-64 encoding of the binary ASN.1 structure (and the markers are added).

You can get back to DER in one of two ways:

1) You can parse and decode the base-64 data in the PEM envelope. To do this, just decode the data between the -----BEGIN/END RSA PRIVATE KEY----- markers.

Or, since you are creating a new key anyway... ;)

2) You could use the -outform DER argument when you generate your key using OpenSSL.

I'm not certain this will work for your application, but maybe it will help get you a little further.

TIP to convert a PEM provate key to DER format, use the rsa utility in OpenSSL:

openssl rsa -inform PEM -outform DER -in privkey.pem -out privkey.der

Upvotes: 3

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