SQL Server

Create ECSDA Signature using Raw r and s Format (not ASN.1)

See more ECC Examples

Demonstrates how to create an ECDSA signature using the raw r/s format.

ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:

(a) Concatenating the raw byte array of r and s
(b) Encoding both into a structured ASN.1 / DER sequence.

This example demonstrates how to create a signature that is a byte array of r and s concatenated.

Note: This example requires Chilkat v9.5.0.97 or greater.

SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

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

    -- To create an ECDSA signature, the data first needs to be hashed.  Then the hash
    -- is signed.

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

    EXEC sp_OAMethod @sb, 'Append', @success OUT, 'The quick brown fox jumps over the lazy dog'
    DECLARE @hash nvarchar(4000)
    EXEC sp_OAMethod @sb, 'GetHash', @hash OUT, 'sha256', 'base64', 'utf-8'

    -- Load the ECDSA key to be used for signing.
    DECLARE @privKey int
    EXEC @hr = sp_OACreate 'Chilkat.PrivateKey', @privKey OUT

    EXEC sp_OAMethod @privKey, 'LoadPemFile', @success OUT, 'qa_data/ecc/secp256r1-key-pkcs8.pem'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @privKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sb
        EXEC @hr = sp_OADestroy @privKey
        RETURN
      END

    DECLARE @prng int
    EXEC @hr = sp_OACreate 'Chilkat.Prng', @prng OUT

    DECLARE @ecdsa int
    EXEC @hr = sp_OACreate 'Chilkat.Ecc', @ecdsa OUT

    -- Produce a signature that is not ASN.1, but is instead the concatenation
    -- of the raw r and s signature parts.
    -- This feature was added in Chilkat v9.5.0.97
    EXEC sp_OASetProperty @ecdsa, 'AsnFormat', 0

    DECLARE @ecdsaSigBase64 nvarchar(4000)
    EXEC sp_OAMethod @ecdsa, 'SignHashENC', @ecdsaSigBase64 OUT, @hash, 'base64', @privKey, @prng
    EXEC sp_OAGetProperty @ecdsa, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @ecdsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sb
        EXEC @hr = sp_OADestroy @privKey
        EXEC @hr = sp_OADestroy @prng
        EXEC @hr = sp_OADestroy @ecdsa
        RETURN
      END


    PRINT 'ECDSA signature = ' + @ecdsaSigBase64

    -- -----------------------------------------------------------
    -- Now let's verify the signature using the public key.

    DECLARE @pubKey int
    EXEC @hr = sp_OACreate 'Chilkat.PublicKey', @pubKey OUT

    EXEC sp_OAMethod @pubKey, 'LoadFromFile', @success OUT, 'qa_data/ecc/secp256r1-pubkey.pem'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @pubKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sb
        EXEC @hr = sp_OADestroy @privKey
        EXEC @hr = sp_OADestroy @prng
        EXEC @hr = sp_OADestroy @ecdsa
        EXEC @hr = sp_OADestroy @pubKey
        RETURN
      END

    -- Note: When verifying, Chilkat will auto-detect the format for both kinds of ECDSA signatures (ASN.1 or binary r+s)
    DECLARE @result int
    EXEC sp_OAMethod @ecdsa, 'VerifyHashENC', @result OUT, @hash, @ecdsaSigBase64, 'base64', @pubKey
    IF @result = 1
      BEGIN

        PRINT 'Signature is valid.'
        EXEC @hr = sp_OADestroy @sb
        EXEC @hr = sp_OADestroy @privKey
        EXEC @hr = sp_OADestroy @prng
        EXEC @hr = sp_OADestroy @ecdsa
        EXEC @hr = sp_OADestroy @pubKey
        RETURN
      END
    IF @result = 0
      BEGIN

        PRINT 'Signature is invalid.'
        EXEC @hr = sp_OADestroy @sb
        EXEC @hr = sp_OADestroy @privKey
        EXEC @hr = sp_OADestroy @prng
        EXEC @hr = sp_OADestroy @ecdsa
        EXEC @hr = sp_OADestroy @pubKey
        RETURN
      END
    IF @result < 0
      BEGIN
        EXEC sp_OAGetProperty @ecdsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0

        PRINT 'The VerifyHashENC method call failed.'
        EXEC @hr = sp_OADestroy @sb
        EXEC @hr = sp_OADestroy @privKey
        EXEC @hr = sp_OADestroy @prng
        EXEC @hr = sp_OADestroy @ecdsa
        EXEC @hr = sp_OADestroy @pubKey
        RETURN
      END

    EXEC @hr = sp_OADestroy @sb
    EXEC @hr = sp_OADestroy @privKey
    EXEC @hr = sp_OADestroy @prng
    EXEC @hr = sp_OADestroy @ecdsa
    EXEC @hr = sp_OADestroy @pubKey


END
GO