B4X

Compute JWK Thumbprint for RSA and EC Public Keys

See more ECC Examples

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.

B4X

Dim success As Boolean = False

Dim pubKey As ChilkatPublicKey
pubKey.Initialize

'  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...

Dim sb As ChilkatStringBuilder
sb.Initialize
sb.Append("{")
sb.Append(Chr(34) & "kty" & Chr(34) & ": " & Chr(34) & "RSA" & Chr(34) & ",")
sb.Append(Chr(34) & "n" & Chr(34) & ": " & Chr(34) & "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAt")
sb.Append("VT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMstn6")
sb.Append("4tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FD")
sb.Append("W2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n9")
sb.Append("1CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINH")
sb.Append("aQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw" & Chr(34) & ",")
sb.Append(Chr(34) & "e" & Chr(34) & ": " & Chr(34) & "AQAB" & Chr(34) & ",")
sb.Append(Chr(34) & "alg" & Chr(34) & ": " & Chr(34) & "RS256" & Chr(34) & ",")
sb.Append(Chr(34) & "kid" & Chr(34) & ": " & Chr(34) & "2011-04-29" & Chr(34))
sb.Append("}")

'  The JWK format is automatically detected..
success = pubKey.LoadFromString(sb.GetAsString)
If success <> True Then
    Log(pubKey.LastErrorText)
    Return
End If


'  Get the JWK thumbprint (using SHA256)
Log("JWK thumbprint: " & pubKey.GetJwkThumbprint("SHA256"))

'  Output:
'  JWK thumbprint: NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs

'  --------------------------------------------------------------
'  Now let's do an EC public key:
sb.Clear
sb.Append("{ ")
sb.Append("  " & Chr(34) & "kty" & Chr(34) & ": " & Chr(34) & "EC" & Chr(34) & ",")
sb.Append("  " & Chr(34) & "crv" & Chr(34) & ": " & Chr(34) & "P-256" & Chr(34) & ",")
sb.Append("  " & Chr(34) & "x" & Chr(34) & ": " & Chr(34) & "tDeeYABgKEAbWicYPCEEI8sP4SRIhHKcHDW7VqrB4LA" & Chr(34) & ",")
sb.Append("  " & Chr(34) & "y" & Chr(34) & ": " & Chr(34) & "J08HOoIZ0rX2Me3bNFZUltfxIk1Hrc8FsLu8VaSxsMI" & Chr(34))
sb.Append("}")

success = pubKey.LoadFromString(sb.GetAsString)
If success <> True Then
    Log(pubKey.LastErrorText)
    Return
End If


'  Get the JWK thumbprint (using SHA256)
Log("JWK thumbprint: " & pubKey.GetJwkThumbprint("SHA256"))

'  Output:
'  JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4