(PowerShell) 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.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

$pubKey = New-Object Chilkat.PublicKey

# 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 = New-Object Chilkat.StringBuilder
$sb.Append("{")
$sb.Append("`"kty`": `"RSA`",")
$sb.Append("`"n`": `"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`",")
$sb.Append("`"e`": `"AQAB`",")
$sb.Append("`"alg`": `"RS256`",")
$sb.Append("`"kid`": `"2011-04-29`"")
$sb.Append("}")

# The JWK format is automatically detected..
$success = $pubKey.LoadFromString($sb.GetAsString())
if ($success -ne $true) {
    $($pubKey.LastErrorText)
    exit
}

# Get the JWK thumbprint (using SHA256)
$("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("  `"kty`": `"EC`",")
$sb.Append("  `"crv`": `"P-256`",")
$sb.Append("  `"x`": `"tDeeYABgKEAbWicYPCEEI8sP4SRIhHKcHDW7VqrB4LA`",")
$sb.Append("  `"y`": `"J08HOoIZ0rX2Me3bNFZUltfxIk1Hrc8FsLu8VaSxsMI`"")
$sb.Append("}")

$success = $pubKey.LoadFromString($sb.GetAsString())
if ($success -ne $true) {
    $($pubKey.LastErrorText)
    exit
}

# Get the JWK thumbprint (using SHA256)
$("JWK thumbprint: " + $pubKey.GetJwkThumbprint("SHA256"))

# Output:
# JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4