Signature transcode to der as required by the JCA.
Signature transcode to der as required by the JCA. Adapted from the implementation in scala-jwt, which itself was adapted from jose4j, which itself was adapted from from org.apache.xml.security.algorithms.implementations.SignatureECDSA in the (Apache 2 licensed) Apache Santuario XML Security library.
the signature to convert to DER
MonadError Instance
ASN.1/DER to the concat required by https://tools.ietf.org/html/rfc7518#section-3.4 Adapted from scala-jwt, itself adapted from jose4j