DataFlex

Compute a Private Key's JWK Thumbprint

Demonstrates the Chilkat PrivateKey.GetJwkThumbprint method, which computes the RFC 7638 thumbprint of the key's public portion using a named hash algorithm. 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 stable, canonical hash of a key's public parameters — a short fingerprint that identifies the key independent of formatting. It is widely used as a key ID (kid) in JWK Sets and JWTs, and for comparing whether two representations are the same key. Because it hashes only the public portion, it can be shared freely even though it is computed here from the private key.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoPrivKey
    String sThumbprint
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  Load a private key to export.
    Get Create (RefClass(cComChilkatPrivateKey)) To hoPrivKey
    If (Not(IsComObjectCreated(hoPrivKey))) Begin
        Send CreateComObject of hoPrivKey
    End
    Get ComLoadPemFile Of hoPrivKey "qa_data/private.pem" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPrivKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Compute the RFC 7638 thumbprint of the key's public portion using the named hash algorithm.
    //  Supported values include "sha256", "sha1", "md5", and others.
    Get ComGetJwkThumbprint Of hoPrivKey "sha256" To sThumbprint
    Get ComLastMethodSuccess Of hoPrivKey To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoPrivKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "JWK thumbprint: " sThumbprint


End_Procedure