Creating message with SHA256 RSA 2048 bits

VCL TMS VCL UI Pack
1

I have to create an appliccation that must sent a message with with SHA256 RSA 2048 bits and receive messages to decrypt. Can I use TMS Cryptography Pack for it. Is it a part of the UI pack or do I have to buy it separatly?

2

TMS Cryptography Pack is a separate product. It is not part of TMS VCL UI Pack.
The support center category for it is:

3

Thank you for your answer. I try to open a new ticket in Cryptography Pack but this is button is disabled, so I try it this way.

When I using chilkat I can encrypt en decrypt a message without probrems. Bu we're using TMS components, so it's logical to get it work in the Cryptography Pack.
If I convert my message to rsa 2056, there's a difference in the encrypted message (TMS and chilkat are not the same). Also when I want to decrypt, procedure RSA.FromPrivateKey() gives an error message: raised exception class ECryptoPack with message 'RSA Key Length not supported'.

How do I get the same results with my chilkat demo?

this is the result of chilkat:

encrypted

xIawYWsk1clicyOxSn6PyHPmvHcBMqXDw9f+ExpjttwgDOCujBwj2rllhaeISRvWzCM2IfqMqG/DqpM5GE1UlF4hsqCz6OrbgZh7qg9YFXAV4HFzHLdpb3CLKvbmyNydyPJ9MjYoVJqzC3RrNVCJ5rND4R/EbgGg/KlXFxLC3KcD/CsnUd+A94a9OGjq5r9HWrMjGXiCwVvBIwz8pSQ51VCfkXLHFE6Td6SjJveIL4nz6VtrNdtfKvEMmCTK9CG2d1/fadHir4CVPYY7HP4k0Wnq9cZnwRuGr2amArd+oQGSkpOHWTiTR5DuczPPM1r1pNFWCtXFUcsc8zYx+gDhjg==

decrypted

Dit is mijn eerste bericht

This is my code in Delphi with TMS

procedure TForm1.Button1Click(Sender: TObject);
var publickey  : string;
    privatekey : string;
    Mijnbericht: string;
    rsa, rsa2 : TRSAEncSign;

begin
  rsa  := TRSAEncSign.create;
  rsa2 := TRSAEncSign.create;
  publickey := '';
  privatekey := '';
  for var t1 := 0 to mmopublic.Lines.Count - 1 do
    publickey := publickey + mmopublic.Lines[t1];
  for var t2 := 0 to mmopublic.Lines.Count - 1 do
    privatekey := privatekey + mmoprivate.Lines[t2];
  mijnbericht := 'Dit is mijn eerste bericht';

  RSA.KeyLength := kl2048;
  RSA.OutputFormat := base64;
  RSA.Unicode := yesUni;
  RSA.FromPublicKey(publickey);

//  RSA.encType := TRSAEncType(0);
  mmoencrypt.lines.Text := RSA.Encrypt(mmoplain.lines.text);

  RSA.KeyLength := kl2048;
  RSA.OutputFormat := base64;
  RSA.Unicode := yesUni;
  RSA.FromPrivateKey(privatekey);
  MMOPlain.lines.Text := RSA.Decrypt(mmoencrypt.lines.text);

  rsa.free;
  rsa2.free;

end;
4

Hi Pieter,
Do you confirm you are using RSA 2056 with Chilkat?
"If I convert my message to rsa 2056, there's a difference in the encrypted message"
Regards,
bernard

5

I'm sorry. Should be 2048. My mistake

6

No problem.

Not knowing Chilkat, the next question is: what is their key format? Is it identical (including byte ordering) to TMS CP RSA key format?

7

I looked at my code again and notised it was generating its own public and private and shouldn't suppost to be.

To the basics.
I have a public and private key in string format. This is I want to use. with the chilkat tool I created this code:

procedure TForm2.Button1Click(Sender: TObject);
var
rsa: HCkRsa;
success: Boolean;
plainText: string;
rsaEncryptor: HCkRsa;
usePrivateKey: Boolean;
encryptedStr: PWideChar;
rsaDecryptor: HCkRsa;
decryptedStr: PWideChar;
jsontext : string;
mysignature : string;
signatureEncoded : string;


pubKey: HCkPublicKey;
sbPem: HCkStringBuilder;

privKey: HCkPrivateKey;
sbPem2: HCkStringBuilder;


begin
//unlock;

//lees the public key vanuit de memo
pubKey := CkPublicKey_Create();
sbPem := CkStringBuilder_Create();
CkStringBuilder_AppendLine(sbPem,'-----BEGIN PUBLIC KEY-----',True);
for var t  := 0 to mmoprivate.lines.Count - 1 do
  CkStringBuilder_AppendLine(sbPem,pchar(mmopublic.lines[t]),True);
CkStringBuilder_AppendLine(sbPem,'-----END PUBLIC KEY-----',True);

success := CkPublicKey_LoadFromString(PubKey,CkStringBuilder__getAsString(sbPem));
if (success <> True) then
begin
  mmolog.Lines.Add(CkPrivateKey__lastErrorText(PubKey));
  Exit;
end;

// lees provate key
privKey := CkPrivateKey_Create();

sbPem2 := CkStringBuilder_Create();
CkStringBuilder_AppendLine(sbPem2,'-----BEGIN RSA PRIVATE KEY-----',True);
for var t  := 0 to mmoprivate.lines.Count - 1 do
  CkStringBuilder_AppendLine(sbPem2,pchar(mmoprivate.lines[t]),True);
CkStringBuilder_AppendLine(sbPem2,'-----END RSA PRIVATE KEY-----',True);

success := CkPrivateKey_LoadPem(privKey,CkStringBuilder__getAsString(sbPem2));
if (success <> True) then
begin
  mmolog.Lines.Add(CkPrivateKey__lastErrorText(privKey));
  Exit;
end;

mmoencrypted.lines.Clear;
mmoDecrypted.lines.Clear;
mmojson.lines.Clear;

rsa := CkRsa_Create();
plainText := 'Dit is mijn eerste bericht';

var MyBase64 : string := plaintext ; //TBase64Encoding.base64.Encode(plainText);

// Start with a new RSA object to demonstrate that all we
// need are the keys previously exported:
rsaEncryptor := CkRsa_Create();

// Encrypted output is always binary.  In this case, we want
// to encode the encrypted bytes in a printable string.
// Our choices are "hex", "base64", "url", "quoted-printable".
CkRsa_putEncodingMode(rsaEncryptor,'base64');

// We'll encrypt with the public key and decrypt with the private
// key.  It's also possible to do the reverse.
success := CkRsa_ImportPublicKeyObj(rsaEncryptor,pubKey);

usePrivateKey := false;
encryptedStr := CkRsa__encryptStringENC(rsaEncryptor,pchar(MyBase64),usePrivateKey);
mmoencrypted.Lines.text := encryptedStr;

mysignature :=  'administratie@gsn.nl' + 'staging@infomedics.nl';

signatureEncoded := sign2(mysignature, encryptedStr);

// Now decrypt:
rsaDecryptor := CkRsa_Create();

CkRsa_putEncodingMode(rsaDecryptor,'base64');
success := CkRsa_ImportPrivateKeyObj(rsaDecryptor,privKey);

usePrivateKey := True;
decryptedStr := CkRsa__decryptStringENC(rsaDecryptor,encryptedStr,usePrivateKey);

mmodecrypted.Lines.text := decryptedStr; //TBase64Encoding.base64.Decode(decryptedStr);

CreateJSon(JSONText, signatureEncoded);
startrequest(JSonText);

mmojson.lines.Text := JSONText;

CkRsa_Dispose(rsa);
CkRsa_Dispose(rsaEncryptor);
CkRsa_Dispose(rsaDecryptor);
CkPublicKey_Dispose(pubKey);
CkPrivateKey_Dispose(privKey);
CkStringBuilder_Dispose(sbPem);

end;


function TForm2.Sign2(aSignature : string; aEncrypted : string) : string;
var
privKey: HCkPrivateKey;
success: Boolean;
sbPem: HCkStringBuilder;
rsa: HCkRsa;
strSigned: PWideChar;
strOriginal: PWideChar;

begin
//  This requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

privKey := CkPrivateKey_Create();

sbPem := CkStringBuilder_Create();
CkStringBuilder_AppendLine(sbPem,'-----BEGIN RSA PRIVATE KEY-----',True);
for var t  := 0 to mmoprivate.lines.Count - 1 do
  CkStringBuilder_AppendLine(sbPem,pchar(mmoprivate.lines[t]),True);
CkStringBuilder_AppendLine(sbPem,'-----END RSA PRIVATE KEY-----',True);

success := CkPrivateKey_LoadPem(privKey,CkStringBuilder__getAsString(sbPem));
if (success <> True) then
  begin
    mmolog.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

rsa := CkRsa_Create();

success := CkRsa_ImportPrivateKeyObj(rsa,privKey);
if (success <> True) then
  begin
    Mmolog.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

var test : string := aSignature + aEncrypted;

//CkRsa_putCharset(rsa,'iso--8859-1');
CkRsa_putEncodingMode(rsa,'base64');
strSigned := CkRsa__SignStringENC(rsa,pwidechar(test),'sha256');

mmosignature.Lines.text := strSigned;

result := string(strSigned);

CkPrivateKey_Dispose(privKey);
CkStringBuilder_Dispose(sbPem);
CkRsa_Dispose(rsa);

end;

With this code I can read my public / privatekey from string, encode a message with the public key and signed it with my private key with the tool chilkat. Is it possible to do this with TMS?

TMS is much faster than chilkat and want to use the rsa because all other componments we're using are from TMS
8

I looked at my code again and notised it was generating its own public and private and shouldn't suppost to be.

To the basics.
I have a public and private key in string format. This is I want to use. with the chilkat tool I created this code:

procedure TForm2.Button1Click(Sender: TObject);
var
rsa: HCkRsa;
success: Boolean;
plainText: string;
rsaEncryptor: HCkRsa;
usePrivateKey: Boolean;
encryptedStr: PWideChar;
rsaDecryptor: HCkRsa;
decryptedStr: PWideChar;
jsontext : string;
mysignature : string;
signatureEncoded : string;


pubKey: HCkPublicKey;
sbPem: HCkStringBuilder;

privKey: HCkPrivateKey;
sbPem2: HCkStringBuilder;


begin
//unlock;

//lees the public key vanuit de memo
pubKey := CkPublicKey_Create();
sbPem := CkStringBuilder_Create();
CkStringBuilder_AppendLine(sbPem,'-----BEGIN PUBLIC KEY-----',True);
for var t  := 0 to mmoprivate.lines.Count - 1 do
  CkStringBuilder_AppendLine(sbPem,pchar(mmopublic.lines[t]),True);
CkStringBuilder_AppendLine(sbPem,'-----END PUBLIC KEY-----',True);

success := CkPublicKey_LoadFromString(PubKey,CkStringBuilder__getAsString(sbPem));
if (success <> True) then
begin
  mmolog.Lines.Add(CkPrivateKey__lastErrorText(PubKey));
  Exit;
end;

// lees provate key
privKey := CkPrivateKey_Create();

sbPem2 := CkStringBuilder_Create();
CkStringBuilder_AppendLine(sbPem2,'-----BEGIN RSA PRIVATE KEY-----',True);
for var t  := 0 to mmoprivate.lines.Count - 1 do
  CkStringBuilder_AppendLine(sbPem2,pchar(mmoprivate.lines[t]),True);
CkStringBuilder_AppendLine(sbPem2,'-----END RSA PRIVATE KEY-----',True);

success := CkPrivateKey_LoadPem(privKey,CkStringBuilder__getAsString(sbPem2));
if (success <> True) then
begin
  mmolog.Lines.Add(CkPrivateKey__lastErrorText(privKey));
  Exit;
end;

mmoencrypted.lines.Clear;
mmoDecrypted.lines.Clear;
mmojson.lines.Clear;

rsa := CkRsa_Create();
plainText := 'Dit is mijn eerste bericht';

var MyBase64 : string := plaintext ; //TBase64Encoding.base64.Encode(plainText);

// Start with a new RSA object to demonstrate that all we
// need are the keys previously exported:
rsaEncryptor := CkRsa_Create();

// Encrypted output is always binary.  In this case, we want
// to encode the encrypted bytes in a printable string.
// Our choices are "hex", "base64", "url", "quoted-printable".
CkRsa_putEncodingMode(rsaEncryptor,'base64');

// We'll encrypt with the public key and decrypt with the private
// key.  It's also possible to do the reverse.
success := CkRsa_ImportPublicKeyObj(rsaEncryptor,pubKey);

usePrivateKey := false;
encryptedStr := CkRsa__encryptStringENC(rsaEncryptor,pchar(MyBase64),usePrivateKey);
mmoencrypted.Lines.text := encryptedStr;

mysignature :=  'administratie@gsn.nl' + 'staging@infomedics.nl';

signatureEncoded := sign2(mysignature, encryptedStr);

// Now decrypt:
rsaDecryptor := CkRsa_Create();

CkRsa_putEncodingMode(rsaDecryptor,'base64');
success := CkRsa_ImportPrivateKeyObj(rsaDecryptor,privKey);

usePrivateKey := True;
decryptedStr := CkRsa__decryptStringENC(rsaDecryptor,encryptedStr,usePrivateKey);

mmodecrypted.Lines.text := decryptedStr; //TBase64Encoding.base64.Decode(decryptedStr);

CreateJSon(JSONText, signatureEncoded);
startrequest(JSonText);

mmojson.lines.Text := JSONText;

CkRsa_Dispose(rsa);
CkRsa_Dispose(rsaEncryptor);
CkRsa_Dispose(rsaDecryptor);
CkPublicKey_Dispose(pubKey);
CkPrivateKey_Dispose(privKey);
CkStringBuilder_Dispose(sbPem);

end;


function TForm2.Sign2(aSignature : string; aEncrypted : string) : string;
var
privKey: HCkPrivateKey;
success: Boolean;
sbPem: HCkStringBuilder;
rsa: HCkRsa;
strSigned: PWideChar;
strOriginal: PWideChar;

begin
//  This requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

privKey := CkPrivateKey_Create();

sbPem := CkStringBuilder_Create();
CkStringBuilder_AppendLine(sbPem,'-----BEGIN RSA PRIVATE KEY-----',True);
for var t  := 0 to mmoprivate.lines.Count - 1 do
  CkStringBuilder_AppendLine(sbPem,pchar(mmoprivate.lines[t]),True);
CkStringBuilder_AppendLine(sbPem,'-----END RSA PRIVATE KEY-----',True);

success := CkPrivateKey_LoadPem(privKey,CkStringBuilder__getAsString(sbPem));
if (success <> True) then
  begin
    mmolog.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

rsa := CkRsa_Create();

success := CkRsa_ImportPrivateKeyObj(rsa,privKey);
if (success <> True) then
  begin
    Mmolog.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

var test : string := aSignature + aEncrypted;

//CkRsa_putCharset(rsa,'iso--8859-1');
CkRsa_putEncodingMode(rsa,'base64');
strSigned := CkRsa__SignStringENC(rsa,pwidechar(test),'sha256');

mmosignature.Lines.text := strSigned;

result := string(strSigned);

CkPrivateKey_Dispose(privKey);
CkStringBuilder_Dispose(sbPem);
CkRsa_Dispose(rsa);

end;

With this code I can read my public / privatekey from string, encode a message with the public key and signed it with my private key with the chilkat tool. Is it possible to do this with TMS?

TMS is much faster than chilkat and want to use the rsa because all other componments we're using are from TMS

9

You will need to use:
procedure FromOpenSSLPrivateKey(filePath: string); to import a key pair from an OpenSSL private key (PEM format)
and then sign with the extracted private key.
I don't understand what you mean by " encode a message with the public key".

10

Probeer het even in het Nederlands. Als dat niet kan, vertaal ik het verhaal wel in het Engels.

Wij hebben een restserver gebouwd, waarbij berichten verstuurd kunnen worden binnen verschillende applicaties. Zo kan een bijvoorbeeld een tandarts met pakket A communiceren met een orthondotist met pakket B. Dit bericht wordt versleuteld. Daar heb ik een public key en private key voor nodig. Om alles secure te houden qua beveiliging wordt het bericht op basis encryptie. van Alle encryptie en ondertekening gebeurt middels (OpenSSL) SHA256 RSA 2048 bits. Als ik een bericht verstuur, maak ik gebruik van de public key. Dit is niet een bestand, maar een string (al weet ik niet zeker of dit zo blijft). De restserver verwacht ook een signature. Deze wordt opgebouwd op basis van mailadres van afzender en ontvanger en het versleutelde bericht. Deze wordt encrypted met de private key. Als dit allemaal is geregeld, wordt een JSON naar de restserver gestuurd.

Dit heb ik werkend met de Chilkat tool. Echter wil ik dat TMS doen (ook vanwege de snelheid). De demo heeft wel een RSA optie, maar klaagt over de lengte van de private key. Als ik deze met kopiëren en plakken in de juiste velden zet, wordt deze afgekort, waardoor er geen volledige sleutel is.

Mijn vraag: hoe realiseer ik dit met TMS en is daar een goede voorbeeld van?

11

Most likely, the key is not a 2048 string and you get an error message. Do you try to use a base64 encoded key from OpenSSL?

12

I don't think we understand each other.

(This is an example and not the real one)
I have a public key file:

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAuI+xw3/UV5X1xPPKwSzw
34PFf4o+YiAGLC4ps6cOgJWW+O4jmcBfyNPg3+OC/nWLmMFK+D30R43BCKPfYHpZ
jFOfOI4j5T0KuZIPcxGAbzyoVvHOWy+v8mdKQBqFttC9hOaCo4SMrPvBJkqtxybC
JJcrfrO8cnBynUD7dTmQkIGQts6+nvLduHANAXGb7Z0algHgldNdWvwAvp5IGynO
51N/TiGAFUNFY4rboOStvtPbQLChcLuPSy7/JvEphB+1bMHzl1XbBoYt2hbO6mQm
lg/elA2e04EsisV0FAb9L+jm1g97BVOAI21yAMMq4h7gOjDsF+qNwQ5XSTZU8RgM
MQIDAQAB
-----END PUBLIC KEY-----

the private key file

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

Can I read these two files with the TMS components and encode text with the public key file and sign it with the private key file?

13

You will need to use the following procedures from the TRSAEncSign class:

  • procedure FromCertificateFile(CertFile: string); import a public key from a PEM certificate file
  • procedure FromPrivateKeyFile(KeyFile: string); import a private key from a PEM private key file

and then sign with the extracted private key. The public key is used to verify your signature and shall be provided to whomever needs to verify it.

14

Okay.
Is het also possible to use a stream?
My problem is every receiver has his own public key. With this key a message will be encrypted. It's not logical to save the public key from the messageserver and to read it as PEM to encrypt the message.

15

Unfortunately, you can't use a steam with this prodecure.

16

okay. I load the public and private with a (PEM) file. It's working when I encrypt a single line. But when I have a JSON to encrypt, the following message occurred:

exception class ECryptoPack with message 'error : in RSA, the message is too long!'.

But my JSON is not very long and can have more characters (especially by info:).

This is my JSON

{
    "Message": {
        "Type": "test",
        "Version": "1"
    },
    "Patient": {
        "Id": 1,
        "Check": ""
    },
    "Project": {
        "Id": 1,
        "Status": "1",
        "Info": "Dit is een test met TMS RSA"
    }
}

Why can't I encrypt this file. Do I get the same error when I sign it?

I use this peace of code:

procedure TTMSRSA.EncryptMessage(aAfzender : TAfzender; const aKey : String; const aOntvanger, PlainText : string);
var rsa       : TRSAEncSign;
    Afzender  : string;
begin
  Afzender := aAfzender.email;
  rsa  := TRSAEncSign.create;
  RSA.KeyLength := kl2048;
  RSA.OutputFormat := base64;
  RSA.Unicode := yesUni;
  RSA.FromPublicKeyFile(akey);
  RSA.FromPrivateKeyFile('c:\temp\myprivate.key');
  fEncodedMsg := RSA.Encrypt(plaintext);
  var mysignature : string :=  Afzender + aOntvanger;
  mysignature := mysignature + fEncodedMsg;
  RSA.signType := TRSASignType(base64);
  fsignatureEncoded := RSA.Sign(mysignature);
  rsa.free;
end;
17

This error usually stems from a padding issue.

RSA is not meant to encrypt data, although you can encrypt anythong with it. It is very slow compared to symmetric encryption algorithm such as AES.

If you do want to encrypt, you need to do so with the recipient's public key. This recipient can then decrypt with his/her private key. You may want to add:

rsa.encType := oaep;

in your code before you encrypt.

Signing uses the sender's private key and can be verified by anyone have the signer's public key.

18

I know that, Bernard and all this comes from the management. It should be compatible with other applications. The message will be idenpendently read without notice of the application itself.

Your option to choose oaep is not resolving the problem. with base64 the restserver can check if the payload and signing are compatible. The restserver is linux / php.

Is there an maximum of characters by TMS. Chilkat is just doing fine.

19

In our C code, the limit is checked with the module size and the padding size:

if (messageLength > modulusSizeBytes - paddingSizeByte) {
	return RSA_MESSAGE_TOO_LONG_XX;
}

XX is a function identifier as there are several locations where this condition is checked.
Basically, I don't know how to fix your problem, except for slicing the initial message or writing a completely new function.