(Ruby) Create a JWS Using ECDSA P-256 SHA-256

Creates and validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256

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'

# This requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

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

# Use the following ECC key loaded from JWK format.
sbJwk = Chilkat::CkStringBuilder.new()
sbJwk.Append("{\"kty\":\"EC\",")
sbJwk.Append("\"crv\":\"P-256\",")
sbJwk.Append("\"x\":\"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\",")
sbJwk.Append("\"y\":\"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\",")
sbJwk.Append("\"d\":\"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI\"")
sbJwk.Append("}")

eccKey = Chilkat::CkPrivateKey.new()
# Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
# into the private key object. (See the online reference documentation..)
success = eccKey.LoadJwk(sbJwk.getAsString())
if (success != true)
    print eccKey.lastErrorText() + "\n";
    exit
end

# Create the JWS Protected Header
jwsProtHdr = Chilkat::CkJsonObject.new()
jwsProtHdr.AppendString("alg","ES256")

jws = Chilkat::CkJws.new()

# Set the protected header:
signatureIndex = 0
jws.SetProtectedHeader(signatureIndex,jwsProtHdr)

# Set the ECC key:
jws.SetPrivateKey(signatureIndex,eccKey)

# Set the payload.
bIncludeBom = false
payloadStr = "In our village, folks say God crumbles up the old moon into stars."
jws.SetPayload(payloadStr,"utf-8",bIncludeBom)

# Create the JWS
# By default, the compact serialization is used.
jwsCompact = jws.createJws()
if (jws.get_LastMethodSuccess() != true)
    print jws.lastErrorText() + "\n";
    exit
end

print "JWS: " + jwsCompact + "\n";

# Note: ECC signatures use random values, so the output will be different each time a signature is produced.
# sample output:
# JWS: eyJhbGciOiJFUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.J6EGTNkeuEjehHHBu0SOKzifm8r35wbx49A5964pxzB7gannyZZPMkK7vmlaPJ-K8Xmm8cZsQySAPC12Xd8avw

# Now load the JWS, validate, and recover the original text.
jws2 = Chilkat::CkJws.new()

# Load the JWS.
success = jws2.LoadJws(jwsCompact)

# eccPubKey is a CkPublicKey
eccPubKey = eccKey.GetPublicKey()

# Set the ECC public key used for validation.
signatureIndex = 0
jws2.SetPublicKey(signatureIndex,eccPubKey)

# Validate the 1st (and only) signature at index 0..
v = jws2.Validate(signatureIndex)
if (v < 0)
    # Perhaps Chilkat was not unlocked or the trial expired..
    print "Method call failed for some other reason." + "\n";
    print jws2.lastErrorText() + "\n";
    exit
end

if (v == 0)
    print "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both." + "\n";
    exit
end

# If we get here, the signature was validated..
print "Signature validated." + "\n";

# Recover the original content:
print jws2.getPayload("utf-8") + "\n";

# Examine the protected header:
# joseHeader is a CkJsonObject
joseHeader = jws2.GetProtectedHeader(signatureIndex)
if (jws2.get_LastMethodSuccess() != true)
    print "No protected header found at the given index." + "\n";
    exit
end

joseHeader.put_EmitCompact(false)

print "Protected (JOSE) header:" + "\n";
print joseHeader.emit() + "\n";

# Output:

# Signature validated.
# In our village, folks say God crumbles up the old moon into stars.
# Protected (JOSE) header:
# { 
#   "alg": "ES256"
# }