Duplicating OpenSSL rsautl (creating RSA signatures)

Demonstrates how to duplicate OpenSSL rsautil RSA signatures.

The Chilkat RSA component's methods for creating RSA signatures (SignBytes, SignBytesENC, SignString, and SignStringENC) are very different from OpenSSL's rsautl command. First, we'll explain what Chilkat's signing methods do, and then what OpenSSL's rsautl does. New signing methods have been added to Chilkat RSA to duplicate OpenSSL rsautl: OpenSslSignBytes, OpenSslSignBytesENC, OpenSslSignString, and OpenSslSignStringENC.

Here's what Chilkat's RSA Sign* methods do:
(Note: Chilkat RSA's Sign* methods generate signatures according to RSA Laboratories' "PKCS #1 v2.0: RSA Cryptography Standard".)

1. Input data is hashed using the hashing algorithm specified.
2. The hash is padded using either PKCS1 v1.5 or PKCS1 PSS padding. PKCS v1.5 involves encoding to ASN.1 before padding.
3. The padded hash is finally RSA signed (i.e. modular exponentiation) and the signature is returned.

OpenSSL rsautl is very different. Here's what it does:

1. The input data is not hashed. It must be a small enough amount of data such that it can be padded and signed. PKCS v1.5 padding is always used. The data is not ASN.1 encoded before padding.
2. The PKCS v1.5 padded data is RSA signed and the signature is returned.

Download Chilkat RSA ActiveX

CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int

    DECLARE @pkey int
    EXEC @hr = sp_OACreate 'Chilkat.PrivateKey', @pkey OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    --  Load the private key from an RSA PEM file:
    EXEC sp_OAMethod @pkey, 'LoadPemFile', @success OUT, 'private.pem'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @pkey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        RETURN
      END

    DECLARE @pkeyXml nvarchar(4000)

    --  Get the private key in XML format:
    EXEC sp_OAMethod @pkey, 'GetXml', @pkeyXml OUT

    DECLARE @rsa int
    EXEC @hr = sp_OACreate 'Chilkat.Rsa', @rsa OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    --  Any string argument automatically begins the 30-day trial.

    EXEC sp_OAMethod @rsa, 'UnlockComponent', @success OUT, '30-day trial'
    IF @success <> 1
      BEGIN
        PRINT 'RSA component unlock failed'
        RETURN
      END

    --  Import the private key into the RSA component:
    EXEC sp_OAMethod @rsa, 'ImportPrivateKey', @success OUT, @pkeyXml
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @rsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        RETURN
      END

    --  This example will sign a string, and receive the signature
    --  in a hex-encoded string.  Therefore, set the encoding mode
    --  to "hex":
    EXEC sp_OASetProperty @rsa, 'EncodingMode', 'hex'

    DECLARE @strData nvarchar(4000)

    SELECT @strData = 'secret'

    --  Create an OpenSSL style signature:
    DECLARE @hexSig nvarchar(4000)

    EXEC sp_OAMethod @rsa, 'OpenSslSignStringENC', @hexSig OUT, @strData


    PRINT @hexSig

    --  Recover the data using the corresponding public key:
    DECLARE @pubkey int
    EXEC @hr = sp_OACreate 'Chilkat.PublicKey', @pubkey OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    --  Load the public key from a PEM file:
    EXEC sp_OAMethod @pubkey, 'LoadOpenSslPemFile', @success OUT, 'public.pem'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @pubkey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        RETURN
      END

    DECLARE @pubkeyXml nvarchar(4000)

    --  Get the public key in XML format:
    EXEC sp_OAMethod @pubkey, 'GetXml', @pubkeyXml OUT

    DECLARE @rsa2 int
    EXEC @hr = sp_OACreate 'Chilkat.Rsa', @rsa2 OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    --  Import the public key into the RSA component:
    EXEC sp_OAMethod @rsa2, 'ImportPublicKey', @success OUT, @pubkeyXml
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @rsa2, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        RETURN
      END

    EXEC sp_OASetProperty @rsa2, 'EncodingMode', 'hex'

    --  Recover the original data.
    DECLARE @originalData nvarchar(4000)

    EXEC sp_OAMethod @rsa2, 'OpenSslVerifyStringENC', @originalData OUT, @hexSig


    PRINT @originalData
END
GO