(Ruby) 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 Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

pubKey = Chilkat::CkPublicKey.new()

# 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 = Chilkat::CkStringBuilder.new()
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 != true)
    print pubKey.lastErrorText() + "\n";
    exit
end

# Get the JWK thumbprint (using SHA256)
print "JWK thumbprint: " + pubKey.getJwkThumbprint("SHA256") + "\n";

# 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 != true)
    print pubKey.lastErrorText() + "\n";
    exit
end

# Get the JWK thumbprint (using SHA256)
print "JWK thumbprint: " + pubKey.getJwkThumbprint("SHA256") + "\n";

# Output:
# JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4