add interfaces to set pkeys directly to ECDSA and PSS algorithms

Author: kleinmrk

include/jwt-cpp/jwt.h

@@ -1025,6 +1025,9 @@ namespace jwt {
 					throw ecdsa_exception(error::ecdsa_error::invalid_key_size);
 			}
 
+			ecdsa(std::shared_ptr<EVP_PKEY> pkey, const EVP_MD* (*md)(), std::string name, size_t siglen)
+				: pkey(pkey), md(md), alg_name(std::move(name)), signature_length(siglen) {}
+
 			/**
 			 * Sign jwt data
 			 * \param data The data to sign
@@ -1384,6 +1387,9 @@ namespace jwt {
 					throw rsa_exception(error::rsa_error::no_key_provided);
 			}
 
+			pss(std::shared_ptr<EVP_PKEY> pkey, const EVP_MD* (*md)(), std::string name)
+				: pkey(pkey), md(md), alg_name(std::move(name)) {}
+
 			/**
 			 * Sign jwt data
 			 * \param data The data to sign
@@ -1595,6 +1601,8 @@ namespace jwt {
 			explicit es256(const std::string& public_key, const std::string& private_key = "",
 						   const std::string& public_key_password = "", const std::string& private_key_password = "")
 				: ecdsa(public_key, private_key, public_key_password, private_key_password, EVP_sha256, "ES256", 64) {}
+
+			explicit es256(std::shared_ptr<EVP_PKEY> pkey) : ecdsa(pkey, EVP_sha256, "ES256", 64) {}
 		};
 		/**
 		 * ES384 algorithm
@@ -1612,6 +1620,8 @@ namespace jwt {
 			explicit es384(const std::string& public_key, const std::string& private_key = "",
 						   const std::string& public_key_password = "", const std::string& private_key_password = "")
 				: ecdsa(public_key, private_key, public_key_password, private_key_password, EVP_sha384, "ES384", 96) {}
+
+			explicit es384(std::shared_ptr<EVP_PKEY> pkey) : ecdsa(pkey, EVP_sha384, "ES384", 96) {}
 		};
 		/**
 		 * ES512 algorithm
@@ -1629,6 +1639,8 @@ namespace jwt {
 			explicit es512(const std::string& public_key, const std::string& private_key = "",
 						   const std::string& public_key_password = "", const std::string& private_key_password = "")
 				: ecdsa(public_key, private_key, public_key_password, private_key_password, EVP_sha512, "ES512", 132) {}
+
+			explicit es512(std::shared_ptr<EVP_PKEY> pkey) : ecdsa(pkey, EVP_sha512, "ES512", 132) {}
 		};
 		/**
 		 * ES256K algorithm
@@ -1645,6 +1657,8 @@ namespace jwt {
 			explicit es256k(const std::string& public_key, const std::string& private_key = "",
 							const std::string& public_key_password = "", const std::string& private_key_password = "")
 				: ecdsa(public_key, private_key, public_key_password, private_key_password, EVP_sha256, "ES256K", 64) {}
+
+			explicit es256k(std::shared_ptr<EVP_PKEY> pkey) : ecdsa(pkey, EVP_sha256, "ES256K", 64) {}
 		};
 
 #if !defined(JWT_OPENSSL_1_0_0) && !defined(JWT_OPENSSL_1_1_0)
@@ -1707,6 +1721,8 @@ namespace jwt {
 			explicit ps256(const std::string& public_key, const std::string& private_key = "",
 						   const std::string& public_key_password = "", const std::string& private_key_password = "")
 				: pss(public_key, private_key, public_key_password, private_key_password, EVP_sha256, "PS256") {}
+
+			explicit ps256(std::shared_ptr<EVP_PKEY> pkey) : pss(pkey, EVP_sha256, "PS256") {}
 		};
 		/**
 		 * PS384 algorithm
@@ -1722,6 +1738,8 @@ namespace jwt {
 			explicit ps384(const std::string& public_key, const std::string& private_key = "",
 						   const std::string& public_key_password = "", const std::string& private_key_password = "")
 				: pss(public_key, private_key, public_key_password, private_key_password, EVP_sha384, "PS384") {}
+
+			explicit ps384(std::shared_ptr<EVP_PKEY> pkey) : pss(pkey, EVP_sha384, "PS384") {}
 		};
 		/**
 		 * PS512 algorithm
@@ -1737,6 +1755,8 @@ namespace jwt {
 			explicit ps512(const std::string& public_key, const std::string& private_key = "",
 						   const std::string& public_key_password = "", const std::string& private_key_password = "")
 				: pss(public_key, private_key, public_key_password, private_key_password, EVP_sha512, "PS512") {}
+
+			explicit ps512(std::shared_ptr<EVP_PKEY> pkey) : pss(pkey, EVP_sha512, "PS512") {}
 		};
 	} // namespace algorithm
 
@@ -3480,6 +3500,8 @@ namespace jwt {
 				return std::make_unique<algo<jwt::algorithm::es384>>(jwt::algorithm::es384(key.get_pkey()));
 			} else if (alg_name == "ES512") {
 				return std::make_unique<algo<jwt::algorithm::es512>>(jwt::algorithm::es512(key.get_pkey()));
+			} else if (alg_name == "ES256K") {
+				return std::make_unique<algo<jwt::algorithm::es256k>>(jwt::algorithm::es256k(key.get_pkey()));
 			} else if (alg_name == "HS256") {
 				return std::make_unique<algo<jwt::algorithm::hs256>>(jwt::algorithm::hs256(key.get_oct_key()));
 			} else if (alg_name == "HS384") {