public static final KeyTemplate rawEcdsaP256Template() {
    return exceptionIsBug(
        () ->
            KeyTemplate.createFrom(
                EcdsaParameters.builder()
                    .setSignatureEncoding(EcdsaParameters.SignatureEncoding.IEEE_P1363)
                    .setCurveType(EcdsaParameters.CurveType.NIST_P256)
                    .setHashType(EcdsaParameters.HashType.SHA256)
                    .setVariant(EcdsaParameters.Variant.NO_PREFIX)
                    .build()));
  }
@return A {@link KeyTemplate} that generates new instances of ECDSA keys with the following
    parameters:
    <ul>
      <li>Hash function: SHA256
      <li>Curve: NIST P-256
      <li>Signature encoding: DER (this is the encoding that Java uses).
      <li>Prefix type: RAW (no prefix).
    </ul>
    Keys generated from this template create raw signatures of exactly 64 bytes. It is
    compatible with JWS and most other libraries.
java_src/src/main/java/com/google/crypto/tink/signature/EcdsaSignKeyManager.java