Lianja

Compute JWK Thumbprint for RSA and EC Public Keys

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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.

Lianja

llSuccess = .F.

loPubKey = createobject("CkPublicKey")

// 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...

loSb = createobject("CkStringBuilder")
loSb.Append("{")
loSb.Append('"kty": "RSA",')
loSb.Append('"n": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAt')
loSb.Append("VT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMstn6")
loSb.Append("4tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FD")
loSb.Append("W2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n9")
loSb.Append("1CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINH")
loSb.Append('aQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",')
loSb.Append('"e": "AQAB",')
loSb.Append('"alg": "RS256",')
loSb.Append('"kid": "2011-04-29"')
loSb.Append("}")

// The JWK format is automatically detected..
llSuccess = loPubKey.LoadFromString(loSb.GetAsString())
if (llSuccess <> .T.) then
    ? loPubKey.LastErrorText
    release loPubKey
    release loSb
    return
endif

// Get the JWK thumbprint (using SHA256)
? "JWK thumbprint: " + loPubKey.GetJwkThumbprint("SHA256")

// Output:
// JWK thumbprint: NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs

// --------------------------------------------------------------
// Now let's do an EC public key:
loSb.Clear()
loSb.Append("{ ")
loSb.Append('  "kty": "EC",')
loSb.Append('  "crv": "P-256",')
loSb.Append('  "x": "tDeeYABgKEAbWicYPCEEI8sP4SRIhHKcHDW7VqrB4LA",')
loSb.Append('  "y": "J08HOoIZ0rX2Me3bNFZUltfxIk1Hrc8FsLu8VaSxsMI"')
loSb.Append("}")

llSuccess = loPubKey.LoadFromString(loSb.GetAsString())
if (llSuccess <> .T.) then
    ? loPubKey.LastErrorText
    release loPubKey
    release loSb
    return
endif

// Get the JWK thumbprint (using SHA256)
? "JWK thumbprint: " + loPubKey.GetJwkThumbprint("SHA256")

// Output:
// JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4


release loPubKey
release loSb