SQL Server

Compute a Public Key's JWK Thumbprint

Demonstrates the Chilkat PublicKey.GetJwkThumbprint method, which returns the RFC 7638 JWK thumbprint for the public key. The only argument is the hash algorithm (for example sha256).

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: A JWK thumbprint is a canonical hash of the key's public parameters — a compact fingerprint that identifies the key regardless of formatting. It is the standard way to derive a stable key ID (kid) and to check whether two representations are the same key. Chilkat builds the required canonical JSON, hashes it with the named algorithm, and returns the result.

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-- 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
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Load a public key to export.  LoadFromFile inspects the content, so it accepts DER, PEM, XML,
    --  JWK, and other supported representations.
    DECLARE @pubKey int
    EXEC @hr = sp_OACreate 'Chilkat.PublicKey', @pubKey OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OAMethod @pubKey, 'LoadFromFile', @success OUT, 'qa_data/public.pem'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @pubKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pubKey
        RETURN
      END

    --  Compute the RFC 7638 JWK thumbprint of the public key using the named hash algorithm.  Common
    --  values include "sha256".
    DECLARE @thumbprint nvarchar(4000)
    EXEC sp_OAMethod @pubKey, 'GetJwkThumbprint', @thumbprint OUT, 'sha256'
    EXEC sp_OAGetProperty @pubKey, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @pubKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pubKey
        RETURN
      END

    PRINT 'JWK thumbprint: ' + @thumbprint

    EXEC @hr = sp_OADestroy @pubKey


END
GO