(PureBasic) Compute JWK Thumbprint for RSA and EC Public Keys

Demonstrates how to compute a JSON Web Key thumbprint for a public key (RSA or ECC).

Note: This example requires Chilkat v9.5.0.66 or greater.

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IncludeFile "CkPublicKey.pb"
IncludeFile "CkStringBuilder.pb"

Procedure ChilkatExample()

    pubKey.i = CkPublicKey::ckCreate()
    If pubKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; A public key can be loaded from any format (binary DER, PEM, etc.)
    ; This example will load the public keys from JWK format, 
    ; and will then compute the JWK thumbprint.

    ; First do it for an RSA public key...

    sb.i = CkStringBuilder::ckCreate()
    If sb.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sb,"{")
    CkStringBuilder::ckAppend(sb,Chr(34) + "kty" + Chr(34) + ": " + Chr(34) + "RSA" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sb,Chr(34) + "n" + Chr(34) + ": " + Chr(34) + "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAt")
    CkStringBuilder::ckAppend(sb,"VT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMstn6")
    CkStringBuilder::ckAppend(sb,"4tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FD")
    CkStringBuilder::ckAppend(sb,"W2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n9")
    CkStringBuilder::ckAppend(sb,"1CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINH")
    CkStringBuilder::ckAppend(sb,"aQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sb,Chr(34) + "e" + Chr(34) + ": " + Chr(34) + "AQAB" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sb,Chr(34) + "alg" + Chr(34) + ": " + Chr(34) + "RS256" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sb,Chr(34) + "kid" + Chr(34) + ": " + Chr(34) + "2011-04-29" + Chr(34))
    CkStringBuilder::ckAppend(sb,"}")

    ; The JWK format is automatically detected..
    success.i = CkPublicKey::ckLoadFromString(pubKey,CkStringBuilder::ckGetAsString(sb))
    If success <> 1
        Debug CkPublicKey::ckLastErrorText(pubKey)
        CkPublicKey::ckDispose(pubKey)
        CkStringBuilder::ckDispose(sb)
        ProcedureReturn
    EndIf

    ; Get the JWK thumbprint (using SHA256)
    Debug "JWK thumbprint: " + CkPublicKey::ckGetJwkThumbprint(pubKey,"SHA256")

    ; Output:
    ; JWK thumbprint: NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs

    ; --------------------------------------------------------------
    ; Now let's do an EC public key:
    CkStringBuilder::ckClear(sb)
    CkStringBuilder::ckAppend(sb,"{ ")
    CkStringBuilder::ckAppend(sb,"  " + Chr(34) + "kty" + Chr(34) + ": " + Chr(34) + "EC" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sb,"  " + Chr(34) + "crv" + Chr(34) + ": " + Chr(34) + "P-256" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sb,"  " + Chr(34) + "x" + Chr(34) + ": " + Chr(34) + "tDeeYABgKEAbWicYPCEEI8sP4SRIhHKcHDW7VqrB4LA" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sb,"  " + Chr(34) + "y" + Chr(34) + ": " + Chr(34) + "J08HOoIZ0rX2Me3bNFZUltfxIk1Hrc8FsLu8VaSxsMI" + Chr(34))
    CkStringBuilder::ckAppend(sb,"}")

    success = CkPublicKey::ckLoadFromString(pubKey,CkStringBuilder::ckGetAsString(sb))
    If success <> 1
        Debug CkPublicKey::ckLastErrorText(pubKey)
        CkPublicKey::ckDispose(pubKey)
        CkStringBuilder::ckDispose(sb)
        ProcedureReturn
    EndIf

    ; Get the JWK thumbprint (using SHA256)
    Debug "JWK thumbprint: " + CkPublicKey::ckGetJwkThumbprint(pubKey,"SHA256")

    ; Output:
    ; JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4


    CkPublicKey::ckDispose(pubKey)
    CkStringBuilder::ckDispose(sb)


    ProcedureReturn
EndProcedure