Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1615 insertions, 0 deletions

diff --git a/src/rgw/jwt-cpp/jwt.h b/src/rgw/jwt-cpp/jwt.h
new file mode 100644
index 000000000..b86fb57b0
--- /dev/null
+++ b/src/rgw/jwt-cpp/jwt.h
@@ -0,0 +1,1615 @@
+#pragma once
+#define PICOJSON_USE_INT64
+#include "picojson/picojson.h"
+#include "base.h"
+#include <set>
+#include <chrono>
+#include <unordered_map>
+#include <memory>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+#include <openssl/pem.h>
+#include <openssl/ec.h>
+#include <openssl/err.h>
+
+//If openssl version less than 1.1
+#if OPENSSL_VERSION_NUMBER < 269484032
+#define OPENSSL10
+#endif
+
+#ifndef JWT_CLAIM_EXPLICIT
+#define JWT_CLAIM_EXPLICIT 1
+#endif
+
+namespace jwt {
+	using date = std::chrono::system_clock::time_point;
+
+	struct signature_verification_exception : public std::runtime_error {
+		signature_verification_exception()
+			: std::runtime_error("signature verification failed")
+		{}
+		explicit signature_verification_exception(const std::string& msg)
+			: std::runtime_error(msg)
+		{}
+		explicit signature_verification_exception(const char* msg)
+			: std::runtime_error(msg)
+		{}
+	};
+	struct signature_generation_exception : public std::runtime_error {
+		signature_generation_exception()
+			: std::runtime_error("signature generation failed")
+		{}
+		explicit signature_generation_exception(const std::string& msg)
+			: std::runtime_error(msg)
+		{}
+		explicit signature_generation_exception(const char* msg)
+			: std::runtime_error(msg)
+		{}
+	};
+	struct rsa_exception : public std::runtime_error {
+		explicit rsa_exception(const std::string& msg)
+			: std::runtime_error(msg)
+		{}
+		explicit rsa_exception(const char* msg)
+			: std::runtime_error(msg)
+		{}
+	};
+	struct ecdsa_exception : public std::runtime_error {
+		explicit ecdsa_exception(const std::string& msg)
+			: std::runtime_error(msg)
+		{}
+		explicit ecdsa_exception(const char* msg)
+			: std::runtime_error(msg)
+		{}
+	};
+	struct token_verification_exception : public std::runtime_error {
+		token_verification_exception()
+			: std::runtime_error("token verification failed")
+		{}
+		explicit token_verification_exception(const std::string& msg)
+			: std::runtime_error("token verification failed: " + msg)
+		{}
+	};
+
+	namespace helper {
+		inline
+		std::string extract_pubkey_from_cert(const std::string& certstr, const std::string& pw = "") {
+			// TODO: Cannot find the exact version this change happended
+#if OPENSSL_VERSION_NUMBER <= 0x1000114fL
+			std::unique_ptr<BIO, decltype(&BIO_free_all)> certbio(BIO_new_mem_buf(const_cast<char*>(certstr.data()), certstr.size()), BIO_free_all);
+#else
+			std::unique_ptr<BIO, decltype(&BIO_free_all)> certbio(BIO_new_mem_buf(certstr.data(), certstr.size()), BIO_free_all);
+#endif
+			std::unique_ptr<BIO, decltype(&BIO_free_all)> keybio(BIO_new(BIO_s_mem()), BIO_free_all);
+
+			std::unique_ptr<X509, decltype(&X509_free)> cert(PEM_read_bio_X509(certbio.get(), nullptr, nullptr, const_cast<char*>(pw.c_str())), X509_free);
+			if (!cert) throw rsa_exception("Error loading cert into memory");
+			std::unique_ptr<EVP_PKEY, decltype(&EVP_PKEY_free)> key(X509_get_pubkey(cert.get()), EVP_PKEY_free);
+			if(!key) throw rsa_exception("Error getting public key from certificate");
+			if(!PEM_write_bio_PUBKEY(keybio.get(), key.get())) throw rsa_exception("Error writing public key data in PEM format");
+			char* ptr = nullptr;
+			auto len = BIO_get_mem_data(keybio.get(), &ptr);
+			if(len <= 0 || ptr == nullptr) throw rsa_exception("Failed to convert pubkey to pem");
+			std::string res(ptr, len);
+			return res;
+		}
+
+		inline
+		std::shared_ptr<EVP_PKEY> load_public_key_from_string(const std::string& key, const std::string& password = "") {
+			std::unique_ptr<BIO, decltype(&BIO_free_all)> pubkey_bio(BIO_new(BIO_s_mem()), BIO_free_all);
+			if(key.substr(0, 27) == "-----BEGIN CERTIFICATE-----") {
+				auto epkey = helper::extract_pubkey_from_cert(key, password);
+				if ((size_t)BIO_write(pubkey_bio.get(), epkey.data(), epkey.size()) != epkey.size())
+					throw rsa_exception("failed to load public key: bio_write failed");
+			} else {
+				if ((size_t)BIO_write(pubkey_bio.get(), key.data(), key.size()) != key.size())
+					throw rsa_exception("failed to load public key: bio_write failed");
+			}
+			
+			std::shared_ptr<EVP_PKEY> pkey(PEM_read_bio_PUBKEY(pubkey_bio.get(), nullptr, nullptr, (void*)password.c_str()), EVP_PKEY_free);
+			if (!pkey)
+				throw rsa_exception("failed to load public key: PEM_read_bio_PUBKEY failed:" + std::string(ERR_error_string(ERR_get_error(), NULL)));
+			return pkey;
+		}
+
+		inline
+		std::shared_ptr<EVP_PKEY> load_private_key_from_string(const std::string& key, const std::string& password = "") {
+			std::unique_ptr<BIO, decltype(&BIO_free_all)> privkey_bio(BIO_new(BIO_s_mem()), BIO_free_all);
+			if ((size_t)BIO_write(privkey_bio.get(), key.data(), key.size()) != key.size())
+				throw rsa_exception("failed to load private key: bio_write failed");
+			std::shared_ptr<EVP_PKEY> pkey(PEM_read_bio_PrivateKey(privkey_bio.get(), nullptr, nullptr, const_cast<char*>(password.c_str())), EVP_PKEY_free);
+			if (!pkey)
+				throw rsa_exception("failed to load private key: PEM_read_bio_PrivateKey failed");
+			return pkey;
+		}
+	}
+
+	namespace algorithm {
+		/**
+		 * "none" algorithm.
+		 * 
+		 * Returns and empty signature and checks if the given signature is empty.
+		 */
+		struct none {
+			/// Return an empty string
+			std::string sign(const std::string&) const {
+				return "";
+			}
+			/// Check if the given signature is empty. JWT's with "none" algorithm should not contain a signature.
+			void verify(const std::string&, const std::string& signature) const {
+				if (!signature.empty())
+					throw signature_verification_exception();
+			}
+			/// Get algorithm name
+			std::string name() const {
+				return "none";
+			}
+		};
+		/**
+		 * Base class for HMAC family of algorithms
+		 */
+		struct hmacsha {
+			/**
+			 * Construct new hmac algorithm
+			 * \param key Key to use for HMAC
+			 * \param md Pointer to hash function
+			 * \param name Name of the algorithm
+			 */
+			hmacsha(std::string key, const EVP_MD*(*md)(), const std::string& name)
+				: secret(std::move(key)), md(md), alg_name(name)
+			{}
+			/**
+			 * Sign jwt data
+			 * \param data The data to sign
+			 * \return HMAC signature for the given data
+			 * \throws signature_generation_exception
+			 */
+			std::string sign(const std::string& data) const {
+				std::string res;
+				res.resize(EVP_MAX_MD_SIZE);
+				unsigned int len = res.size();
+				if (HMAC(md(), secret.data(), secret.size(), (const unsigned char*)data.data(), data.size(), (unsigned char*)res.data(), &len) == nullptr)
+					throw signature_generation_exception();
+				res.resize(len);
+				return res;
+			}
+			/**
+			 * Check if signature is valid
+			 * \param data The data to check signature against
+			 * \param signature Signature provided by the jwt
+			 * \throws signature_verification_exception If the provided signature does not match
+			 */
+			void verify(const std::string& data, const std::string& signature) const {
+				try {
+					auto res = sign(data);
+					bool matched = true;
+					for (size_t i = 0; i < std::min<size_t>(res.size(), signature.size()); i++)
+						if (res[i] != signature[i])
+							matched = false;
+					if (res.size() != signature.size())
+						matched = false;
+					if (!matched)
+						throw signature_verification_exception();
+				}
+				catch (const signature_generation_exception&) {
+					throw signature_verification_exception();
+				}
+			}
+			/**
+			 * Returns the algorithm name provided to the constructor
+			 * \return Algorithmname
+			 */
+			std::string name() const {
+				return alg_name;
+			}
+		private:
+			/// HMAC secrect
+			const std::string secret;
+			/// HMAC hash generator
+			const EVP_MD*(*md)();
+			/// Algorithmname
+			const std::string alg_name;
+		};
+		/**
+		 * Base class for RSA family of algorithms
+		 */
+		struct rsa {
+			/**
+			 * Construct new rsa algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 * \param md Pointer to hash function
+			 * \param name Name of the algorithm
+			 */
+			rsa(const std::string& public_key, const std::string& private_key, const std::string& public_key_password, const std::string& private_key_password, const EVP_MD*(*md)(), const std::string& name)
+				: md(md), alg_name(name)
+			{
+				if (!private_key.empty()) {
+					pkey = helper::load_private_key_from_string(private_key, private_key_password);
+				} else if(!public_key.empty()) {
+					pkey = helper::load_public_key_from_string(public_key, public_key_password);
+				} else
+					throw rsa_exception("at least one of public or private key need to be present");
+			}
+			/**
+			 * Sign jwt data
+			 * \param data The data to sign
+			 * \return RSA signature for the given data
+			 * \throws signature_generation_exception
+			 */
+			std::string sign(const std::string& data) const {
+#ifdef OPENSSL10
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_destroy)> ctx(EVP_MD_CTX_create(), EVP_MD_CTX_destroy);
+#else
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_free)> ctx(EVP_MD_CTX_create(), EVP_MD_CTX_free);
+#endif
+				if (!ctx)
+					throw signature_generation_exception("failed to create signature: could not create context");
+				if (!EVP_SignInit(ctx.get(), md()))
+					throw signature_generation_exception("failed to create signature: SignInit failed");
+
+				std::string res;
+				res.resize(EVP_PKEY_size(pkey.get()));
+				unsigned int len = 0;
+
+				if (!EVP_SignUpdate(ctx.get(), data.data(), data.size()))
+					throw signature_generation_exception();
+				if (!EVP_SignFinal(ctx.get(), (unsigned char*)res.data(), &len, pkey.get()))
+					throw signature_generation_exception();
+
+				res.resize(len);
+				return res;
+			}
+			/**
+			 * Check if signature is valid
+			 * \param data The data to check signature against
+			 * \param signature Signature provided by the jwt
+			 * \throws signature_verification_exception If the provided signature does not match
+			 */
+			void verify(const std::string& data, const std::string& signature) const {
+#ifdef OPENSSL10
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_destroy)> ctx(EVP_MD_CTX_create(), EVP_MD_CTX_destroy);
+#else
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_free)> ctx(EVP_MD_CTX_create(), EVP_MD_CTX_free);
+#endif
+				if (!ctx)
+					throw signature_verification_exception("failed to verify signature: could not create context");
+				if (!EVP_VerifyInit(ctx.get(), md()))
+					throw signature_verification_exception("failed to verify signature: VerifyInit failed");
+				if (!EVP_VerifyUpdate(ctx.get(), data.data(), data.size()))
+					throw signature_verification_exception("failed to verify signature: VerifyUpdate failed");
+				auto res = EVP_VerifyFinal(ctx.get(), (const unsigned char*)signature.data(), signature.size(), pkey.get());
+				if (res != 1)
+					throw signature_verification_exception("evp verify final failed: " + std::to_string(res) + " " + ERR_error_string(ERR_get_error(), NULL));
+			}
+			/**
+			 * Returns the algorithm name provided to the constructor
+			 * \return Algorithmname
+			 */
+			std::string name() const {
+				return alg_name;
+			}
+		private:
+			/// OpenSSL structure containing converted keys
+			std::shared_ptr<EVP_PKEY> pkey;
+			/// Hash generator
+			const EVP_MD*(*md)();
+			/// Algorithmname
+			const std::string alg_name;
+		};
+		/**
+		 * Base class for ECDSA family of algorithms
+		 */
+		struct ecdsa {
+			/**
+			 * Construct new ecdsa algorithm
+			 * \param public_key ECDSA public key in PEM format
+			 * \param private_key ECDSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 * \param md Pointer to hash function
+			 * \param name Name of the algorithm
+			 */
+			ecdsa(const std::string& public_key, const std::string& private_key, const std::string& public_key_password, const std::string& private_key_password, const EVP_MD*(*md)(), const std::string& name, size_t siglen)
+				: md(md), alg_name(name), signature_length(siglen)
+			{
+				if (!public_key.empty()) {
+					std::unique_ptr<BIO, decltype(&BIO_free_all)> pubkey_bio(BIO_new(BIO_s_mem()), BIO_free_all);
+					if(public_key.substr(0, 27) == "-----BEGIN CERTIFICATE-----") {
+						auto epkey = helper::extract_pubkey_from_cert(public_key, public_key_password);
+						if ((size_t)BIO_write(pubkey_bio.get(), epkey.data(), epkey.size()) != epkey.size())
+							throw ecdsa_exception("failed to load public key: bio_write failed");
+					} else  {
+						if ((size_t)BIO_write(pubkey_bio.get(), public_key.data(), public_key.size()) != public_key.size())
+							throw ecdsa_exception("failed to load public key: bio_write failed");
+					}
+
+					pkey.reset(PEM_read_bio_EC_PUBKEY(pubkey_bio.get(), nullptr, nullptr, (void*)public_key_password.c_str()), EC_KEY_free);
+					if (!pkey)
+						throw ecdsa_exception("failed to load public key: PEM_read_bio_EC_PUBKEY failed:" + std::string(ERR_error_string(ERR_get_error(), NULL)));
+					size_t keysize = EC_GROUP_get_degree(EC_KEY_get0_group(pkey.get()));
+					if(keysize != signature_length*4 && (signature_length != 132 || keysize != 521))
+						throw ecdsa_exception("invalid key size");
+				}
+
+				if (!private_key.empty()) {
+					std::unique_ptr<BIO, decltype(&BIO_free_all)> privkey_bio(BIO_new(BIO_s_mem()), BIO_free_all);
+					if ((size_t)BIO_write(privkey_bio.get(), private_key.data(), private_key.size()) != private_key.size())
+						throw rsa_exception("failed to load private key: bio_write failed");
+					pkey.reset(PEM_read_bio_ECPrivateKey(privkey_bio.get(), nullptr, nullptr, const_cast<char*>(private_key_password.c_str())), EC_KEY_free);
+					if (!pkey)
+						throw rsa_exception("failed to load private key: PEM_read_bio_ECPrivateKey failed");
+					size_t keysize = EC_GROUP_get_degree(EC_KEY_get0_group(pkey.get()));
+					if(keysize != signature_length*4 && (signature_length != 132 || keysize != 521))
+						throw ecdsa_exception("invalid key size");
+				}
+				if(!pkey)
+					throw rsa_exception("at least one of public or private key need to be present");
+
+				if(EC_KEY_check_key(pkey.get()) == 0)
+					throw ecdsa_exception("failed to load key: key is invalid");
+			}
+			/**
+			 * Sign jwt data
+			 * \param data The data to sign
+			 * \return ECDSA signature for the given data
+			 * \throws signature_generation_exception
+			 */
+			std::string sign(const std::string& data) const {
+				const std::string hash = generate_hash(data);
+
+				std::unique_ptr<ECDSA_SIG, decltype(&ECDSA_SIG_free)>
+					sig(ECDSA_do_sign((const unsigned char*)hash.data(), hash.size(), pkey.get()), ECDSA_SIG_free);
+				if(!sig)
+					throw signature_generation_exception();
+#ifdef OPENSSL10
+
+				auto rr = bn2raw(sig->r);
+				auto rs = bn2raw(sig->s);
+#else
+				const BIGNUM *r;
+				const BIGNUM *s;
+				ECDSA_SIG_get0(sig.get(), &r, &s);
+				auto rr = bn2raw(r);
+				auto rs = bn2raw(s);
+#endif
+				if(rr.size() > signature_length/2 || rs.size() > signature_length/2)
+					throw std::logic_error("bignum size exceeded expected length");
+				while(rr.size() != signature_length/2) rr = '\0' + rr;
+				while(rs.size() != signature_length/2) rs = '\0' + rs;
+				return rr + rs;
+			}
+
+			/**
+			 * Check if signature is valid
+			 * \param data The data to check signature against
+			 * \param signature Signature provided by the jwt
+			 * \throws signature_verification_exception If the provided signature does not match
+			 */
+			void verify(const std::string& data, const std::string& signature) const {
+				const std::string hash = generate_hash(data);
+				auto r = raw2bn(signature.substr(0, signature.size() / 2));
+				auto s = raw2bn(signature.substr(signature.size() / 2));
+
+#ifdef OPENSSL10
+				ECDSA_SIG sig;
+				sig.r = r.get();
+				sig.s = s.get();
+
+				if(ECDSA_do_verify((const unsigned char*)hash.data(), hash.size(), &sig, pkey.get()) != 1)
+					throw signature_verification_exception("Invalid signature");
+#else
+				std::unique_ptr<ECDSA_SIG, decltype(&ECDSA_SIG_free)> sig(ECDSA_SIG_new(), ECDSA_SIG_free);
+
+				ECDSA_SIG_set0(sig.get(), r.release(), s.release());
+
+				if(ECDSA_do_verify((const unsigned char*)hash.data(), hash.size(), sig.get(), pkey.get()) != 1)
+					throw signature_verification_exception("Invalid signature");
+#endif
+			}
+			/**
+			 * Returns the algorithm name provided to the constructor
+			 * \return Algorithmname
+			 */
+			std::string name() const {
+				return alg_name;
+			}
+		private:
+			/**
+			 * Convert a OpenSSL BIGNUM to a std::string
+			 * \param bn BIGNUM to convert
+			 * \return bignum as string
+			 */
+#ifdef OPENSSL10
+			static std::string bn2raw(BIGNUM* bn)
+#else
+			static std::string bn2raw(const BIGNUM* bn)
+#endif
+			{
+				std::string res;
+				res.resize(BN_num_bytes(bn));
+				BN_bn2bin(bn, (unsigned char*)res.data());
+				return res;
+			}
+			/**
+			 * Convert an std::string to a OpenSSL BIGNUM
+			 * \param raw String to convert
+			 * \return BIGNUM representation
+			 */
+			static std::unique_ptr<BIGNUM, decltype(&BN_free)> raw2bn(const std::string& raw) {
+				return std::unique_ptr<BIGNUM, decltype(&BN_free)>(BN_bin2bn((const unsigned char*)raw.data(), raw.size(), nullptr), BN_free);
+			}
+
+			/**
+			 * Hash the provided data using the hash function specified in constructor
+			 * \param data Data to hash
+			 * \return Hash of data
+			 */
+			std::string generate_hash(const std::string& data) const {
+#ifdef OPENSSL10
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_destroy)> ctx(EVP_MD_CTX_create(), &EVP_MD_CTX_destroy);
+#else
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_free)> ctx(EVP_MD_CTX_new(), EVP_MD_CTX_free);
+#endif
+				if(EVP_DigestInit(ctx.get(), md()) == 0)
+					throw signature_generation_exception("EVP_DigestInit failed");
+				if(EVP_DigestUpdate(ctx.get(), data.data(), data.size()) == 0)
+					throw signature_generation_exception("EVP_DigestUpdate failed");
+				unsigned int len = 0;
+				std::string res;
+				res.resize(EVP_MD_CTX_size(ctx.get()));
+				if(EVP_DigestFinal(ctx.get(), (unsigned char*)res.data(), &len) == 0)
+					throw signature_generation_exception("EVP_DigestFinal failed");
+				res.resize(len);
+				return res;
+			}
+
+			/// OpenSSL struct containing keys
+			std::shared_ptr<EC_KEY> pkey;
+			/// Hash generator function
+			const EVP_MD*(*md)();
+			/// Algorithmname
+			const std::string alg_name;
+			/// Length of the resulting signature
+			const size_t signature_length;
+		};
+
+		/**
+		 * Base class for PSS-RSA family of algorithms
+		 */
+		struct pss {
+			/**
+			 * Construct new pss algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 * \param md Pointer to hash function
+			 * \param name Name of the algorithm
+			 */
+			pss(const std::string& public_key, const std::string& private_key, const std::string& public_key_password, const std::string& private_key_password, const EVP_MD*(*md)(), const std::string& name)
+				: md(md), alg_name(name)
+			{
+				if (!private_key.empty()) {
+					pkey = helper::load_private_key_from_string(private_key, private_key_password);
+				} else if(!public_key.empty()) {
+					pkey = helper::load_public_key_from_string(public_key, public_key_password);
+				} else
+					throw rsa_exception("at least one of public or private key need to be present");
+			}
+			/**
+			 * Sign jwt data
+			 * \param data The data to sign
+			 * \return ECDSA signature for the given data
+			 * \throws signature_generation_exception
+			 */
+			std::string sign(const std::string& data) const {
+				auto hash = this->generate_hash(data);
+
+				std::unique_ptr<RSA, decltype(&RSA_free)> key(EVP_PKEY_get1_RSA(pkey.get()), RSA_free);
+				const int size = RSA_size(key.get());
+
+				std::string padded(size, 0x00);
+				if (!RSA_padding_add_PKCS1_PSS_mgf1(key.get(), (unsigned char*)padded.data(), (const unsigned char*)hash.data(), md(), md(), -1))  
+					throw signature_generation_exception("failed to create signature: RSA_padding_add_PKCS1_PSS_mgf1 failed");
+
+				std::string res(size, 0x00);
+				if (RSA_private_encrypt(size, (const unsigned char*)padded.data(), (unsigned char*)res.data(), key.get(), RSA_NO_PADDING) < 0)
+					throw signature_generation_exception("failed to create signature: RSA_private_encrypt failed");
+				return res;
+			}
+			/**
+			 * Check if signature is valid
+			 * \param data The data to check signature against
+			 * \param signature Signature provided by the jwt
+			 * \throws signature_verification_exception If the provided signature does not match
+			 */
+			void verify(const std::string& data, const std::string& signature) const {
+				auto hash = this->generate_hash(data);
+
+				std::unique_ptr<RSA, decltype(&RSA_free)> key(EVP_PKEY_get1_RSA(pkey.get()), RSA_free);
+				const int size = RSA_size(key.get());
+				
+				std::string sig(size, 0x00);
+				if(!RSA_public_decrypt(signature.size(), (const unsigned char*)signature.data(), (unsigned char*)sig.data(), key.get(), RSA_NO_PADDING))
+					throw signature_verification_exception("Invalid signature");
+				
+				if(!RSA_verify_PKCS1_PSS_mgf1(key.get(), (const unsigned char*)hash.data(), md(), md(), (const unsigned char*)sig.data(), -1))
+					throw signature_verification_exception("Invalid signature");
+			}
+			/**
+			 * Returns the algorithm name provided to the constructor
+			 * \return Algorithmname
+			 */
+			std::string name() const {
+				return alg_name;
+			}
+		private:
+			/**
+			 * Hash the provided data using the hash function specified in constructor
+			 * \param data Data to hash
+			 * \return Hash of data
+			 */
+			std::string generate_hash(const std::string& data) const {
+#ifdef OPENSSL10
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_destroy)> ctx(EVP_MD_CTX_create(), &EVP_MD_CTX_destroy);
+#else
+				std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_free)> ctx(EVP_MD_CTX_new(), EVP_MD_CTX_free);
+#endif
+				if(EVP_DigestInit(ctx.get(), md()) == 0)
+					throw signature_generation_exception("EVP_DigestInit failed");
+				if(EVP_DigestUpdate(ctx.get(), data.data(), data.size()) == 0)
+					throw signature_generation_exception("EVP_DigestUpdate failed");
+				unsigned int len = 0;
+				std::string res;
+				res.resize(EVP_MD_CTX_size(ctx.get()));
+				if(EVP_DigestFinal(ctx.get(), (unsigned char*)res.data(), &len) == 0)
+					throw signature_generation_exception("EVP_DigestFinal failed");
+				res.resize(len);
+				return res;
+			}
+			
+			/// OpenSSL structure containing keys
+			std::shared_ptr<EVP_PKEY> pkey;
+			/// Hash generator function
+			const EVP_MD*(*md)();
+			/// Algorithmname
+			const std::string alg_name;
+		};
+
+		/**
+		 * HS256 algorithm
+		 */
+		struct hs256 : public hmacsha {
+			/**
+			 * Construct new instance of algorithm
+			 * \param key HMAC signing key
+			 */
+			explicit hs256(std::string key)
+				: hmacsha(std::move(key), EVP_sha256, "HS256")
+			{}
+		};
+		/**
+		 * HS384 algorithm
+		 */
+		struct hs384 : public hmacsha {
+			/**
+			 * Construct new instance of algorithm
+			 * \param key HMAC signing key
+			 */
+			explicit hs384(std::string key)
+				: hmacsha(std::move(key), EVP_sha384, "HS384")
+			{}
+		};
+		/**
+		 * HS512 algorithm
+		 */
+		struct hs512 : public hmacsha {
+			/**
+			 * Construct new instance of algorithm
+			 * \param key HMAC signing key
+			 */
+			explicit hs512(std::string key)
+				: hmacsha(std::move(key), EVP_sha512, "HS512")
+			{}
+		};
+		/**
+		 * RS256 algorithm
+		 */
+		struct rs256 : public rsa {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			explicit rs256(const std::string& public_key, const std::string& private_key = "", const std::string& public_key_password = "", const std::string& private_key_password = "")
+				: rsa(public_key, private_key, public_key_password, private_key_password, EVP_sha256, "RS256")
+			{}
+		};
+		/**
+		 * RS384 algorithm
+		 */
+		struct rs384 : public rsa {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			explicit rs384(const std::string& public_key, const std::string& private_key = "", const std::string& public_key_password = "", const std::string& private_key_password = "")
+				: rsa(public_key, private_key, public_key_password, private_key_password, EVP_sha384, "RS384")
+			{}
+		};
+		/**
+		 * RS512 algorithm
+		 */
+		struct rs512 : public rsa {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			explicit rs512(const std::string& public_key, const std::string& private_key = "", const std::string& public_key_password = "", const std::string& private_key_password = "")
+				: rsa(public_key, private_key, public_key_password, private_key_password, EVP_sha512, "RS512")
+			{}
+		};
+		/**
+		 * ES256 algorithm
+		 */
+		struct es256 : public ecdsa {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key ECDSA public key in PEM format
+			 * \param private_key ECDSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			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)
+			{}
+		};
+		/**
+		 * ES384 algorithm
+		 */
+		struct es384 : public ecdsa {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key ECDSA public key in PEM format
+			 * \param private_key ECDSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			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)
+			{}
+		};
+		/**
+		 * ES512 algorithm
+		 */
+		struct es512 : public ecdsa {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key ECDSA public key in PEM format
+			 * \param private_key ECDSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			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)
+			{}
+		};
+
+		/**
+		 * PS256 algorithm
+		 */
+		struct ps256 : public pss {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			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")
+			{}
+		};
+		/**
+		 * PS384 algorithm
+		 */
+		struct ps384 : public pss {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			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")
+			{}
+		};
+		/**
+		 * PS512 algorithm
+		 */
+		struct ps512 : public pss {
+			/**
+			 * Construct new instance of algorithm
+			 * \param public_key RSA public key in PEM format
+			 * \param private_key RSA private key or empty string if not available. If empty, signing will always fail.
+			 * \param public_key_password Password to decrypt public key pem.
+			 * \param privat_key_password Password to decrypt private key pem.
+			 */
+			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")
+			{}
+		};
+	}
+
+	/**
+	 * Convenience wrapper for JSON value
+	 */
+	class claim {
+		picojson::value val;
+	public:
+		enum class type {
+			null,
+			boolean,
+			number,
+			string,
+			array,
+			object,
+			int64
+		};
+
+		claim()
+			: val()
+		{}
+#if JWT_CLAIM_EXPLICIT
+		explicit claim(std::string s)
+			: val(std::move(s))
+		{}
+		explicit claim(const date& s)
+			: val(int64_t(std::chrono::system_clock::to_time_t(s)))
+		{}
+		explicit claim(const std::set<std::string>& s)
+			: val(picojson::array(s.cbegin(), s.cend()))
+		{}
+		explicit claim(const picojson::value& val)
+			: val(val)
+		{}
+#else
+		claim(std::string s)
+			: val(std::move(s))
+		{}
+		claim(const date& s)
+			: val(int64_t(std::chrono::system_clock::to_time_t(s)))
+		{}
+		claim(const std::set<std::string>& s)
+			: val(picojson::array(s.cbegin(), s.cend()))
+		{}
+		claim(const picojson::value& val)
+			: val(val)
+		{}
+#endif
+
+		template<typename Iterator>
+		claim(Iterator start, Iterator end)
+			: val(picojson::array())
+		{
+			auto& arr = val.get<picojson::array>();
+			for(; start != end; start++) {
+				arr.push_back(picojson::value(*start));
+			}
+		}
+
+		/**
+		 * Get wrapped json object
+		 * \return Wrapped json object
+		 */
+		picojson::value to_json() const {
+			return val;
+		}
+
+		/**
+		 * Get type of contained object
+		 * \return Type
+		 * \throws std::logic_error An internal error occured
+		 */
+		type get_type() const {
+			if (val.is<picojson::null>()) return type::null;
+			else if (val.is<bool>()) return type::boolean;
+			else if (val.is<int64_t>()) return type::int64;
+			else if (val.is<double>()) return type::number;
+			else if (val.is<std::string>()) return type::string;
+			else if (val.is<picojson::array>()) return type::array;
+			else if (val.is<picojson::object>()) return type::object;
+			else throw std::logic_error("internal error");
+		}
+
+		/**
+		 * Get the contained object as a string
+		 * \return content as string
+		 * \throws std::bad_cast Content was not a string
+		 */
+		const std::string& as_string() const {
+			if (!val.is<std::string>())
+				throw std::bad_cast();
+			return val.get<std::string>();
+		}
+		/**
+		 * Get the contained object as a date
+		 * \return content as date
+		 * \throws std::bad_cast Content was not a date
+		 */
+		date as_date() const {
+			return std::chrono::system_clock::from_time_t(as_int());
+		}
+		/**
+		 * Get the contained object as an array
+		 * \return content as array
+		 * \throws std::bad_cast Content was not an array
+		 */
+		const picojson::array& as_array() const {
+			if (!val.is<picojson::array>())
+				throw std::bad_cast();
+			return val.get<picojson::array>();
+		}
+		/**
+		 * Get the contained object as a set of strings
+		 * \return content as set of strings
+		 * \throws std::bad_cast Content was not a set
+		 */
+		const std::set<std::string> as_set() const {
+			std::set<std::string> res;
+			for(auto& e : as_array()) {
+				if(!e.is<std::string>())
+					throw std::bad_cast();
+				res.insert(e.get<std::string>());
+			}
+			return res;
+		}
+		/**
+		 * Get the contained object as an integer
+		 * \return content as int
+		 * \throws std::bad_cast Content was not an int
+		 */
+		int64_t as_int() const {
+			if (!val.is<int64_t>())
+				throw std::bad_cast();
+			return val.get<int64_t>();
+		}
+		/**
+		 * Get the contained object as a bool
+		 * \return content as bool
+		 * \throws std::bad_cast Content was not a bool
+		 */
+		bool as_bool() const {
+			if (!val.is<bool>())
+				throw std::bad_cast();
+			return val.get<bool>();
+		}
+		/**
+		 * Get the contained object as a number
+		 * \return content as double
+		 * \throws std::bad_cast Content was not a number
+		 */
+		double as_number() const {
+			if (!val.is<double>())
+				throw std::bad_cast();
+			return val.get<double>();
+		}
+		/**
+		 * Get the contained object as an object
+		 * \return content as object
+		 * \throws std::bad_cast Content was not an object
+		 */
+		const picojson::object& as_object() const {
+			if (!val.is<picojson::object>())
+				throw std::bad_cast();
+			return val.get<picojson::object>();
+		}
+	};
+
+	/**
+	 * Base class that represents a token payload.
+	 * Contains Convenience accessors for common claims.
+	 */
+	class payload {
+	protected:
+		std::unordered_map<std::string, claim> payload_claims;
+	public:
+		/**
+		 * Check if issuer is present ("iss")
+		 * \return true if present, false otherwise
+		 */
+		bool has_issuer() const noexcept { return has_payload_claim("iss"); }
+		/**
+		 * Check if subject is present ("sub")
+		 * \return true if present, false otherwise
+		 */
+		bool has_subject() const noexcept { return has_payload_claim("sub"); }
+		/**
+		 * Check if audience is present ("aud")
+		 * \return true if present, false otherwise
+		 */
+		bool has_audience() const noexcept { return has_payload_claim("aud"); }
+		/**
+		 * Check if expires is present ("exp")
+		 * \return true if present, false otherwise
+		 */
+		bool has_expires_at() const noexcept { return has_payload_claim("exp"); }
+		/**
+		 * Check if not before is present ("nbf")
+		 * \return true if present, false otherwise
+		 */
+		bool has_not_before() const noexcept { return has_payload_claim("nbf"); }
+		/**
+		 * Check if issued at is present ("iat")
+		 * \return true if present, false otherwise
+		 */
+		bool has_issued_at() const noexcept { return has_payload_claim("iat"); }
+		/**
+		 * Check if token id is present ("jti")
+		 * \return true if present, false otherwise
+		 */
+		bool has_id() const noexcept { return has_payload_claim("jti"); }
+		/**
+		 * Get issuer claim
+		 * \return issuer as string
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a string (Should not happen in a valid token)
+		 */
+		const std::string& get_issuer() const { return get_payload_claim("iss").as_string(); }
+		/**
+		 * Get subject claim
+		 * \return subject as string
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a string (Should not happen in a valid token)
+		 */
+		const std::string& get_subject() const { return get_payload_claim("sub").as_string(); }
+		/**
+		 * Get audience claim
+		 * \return audience as a set of strings
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a set (Should not happen in a valid token)
+		 */
+		std::set<std::string> get_audience() const { 
+			auto aud = get_payload_claim("aud");
+			if(aud.get_type() == jwt::claim::type::string) return { aud.as_string()};
+			else return aud.as_set();
+		}
+		/**
+		 * Get expires claim
+		 * \return expires as a date in utc
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a date (Should not happen in a valid token)
+		 */
+		const date get_expires_at() const { return get_payload_claim("exp").as_date(); }
+		/**
+		 * Get not valid before claim
+		 * \return nbf date in utc
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a date (Should not happen in a valid token)
+		 */
+		const date get_not_before() const { return get_payload_claim("nbf").as_date(); }
+		/**
+		 * Get issued at claim
+		 * \return issued at as date in utc
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a date (Should not happen in a valid token)
+		 */
+		const date get_issued_at() const { return get_payload_claim("iat").as_date(); }
+		/**
+		 * Get id claim
+		 * \return id as string
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a string (Should not happen in a valid token)
+		 */
+		const std::string& get_id() const { return get_payload_claim("jti").as_string(); }
+		/**
+		 * Check if a payload claim is present
+		 * \return true if claim was present, false otherwise
+		 */
+		bool has_payload_claim(const std::string& name) const noexcept { return payload_claims.count(name) != 0; }
+		/**
+		 * Get payload claim
+		 * \return Requested claim
+		 * \throws std::runtime_error If claim was not present
+		 */
+		const claim& get_payload_claim(const std::string& name) const {
+			if (!has_payload_claim(name))
+				throw std::runtime_error("claim not found");
+			return payload_claims.at(name);
+		}
+		/**
+		 * Get all payload claims
+		 * \return map of claims
+		 */
+		std::unordered_map<std::string, claim> get_payload_claims() const { return payload_claims; }
+	};
+
+	/**
+	 * Base class that represents a token header.
+	 * Contains Convenience accessors for common claims.
+	 */
+	class header {
+	protected:
+		std::unordered_map<std::string, claim> header_claims;
+	public:
+		/**
+		 * Check if algortihm is present ("alg")
+		 * \return true if present, false otherwise
+		 */
+		bool has_algorithm() const noexcept { return has_header_claim("alg"); }
+		/**
+		 * Check if type is present ("typ")
+		 * \return true if present, false otherwise
+		 */
+		bool has_type() const noexcept { return has_header_claim("typ"); }
+		/**
+		 * Check if content type is present ("cty")
+		 * \return true if present, false otherwise
+		 */
+		bool has_content_type() const noexcept { return has_header_claim("cty"); }
+		/**
+		 * Check if key id is present ("kid")
+		 * \return true if present, false otherwise
+		 */
+		bool has_key_id() const noexcept { return has_header_claim("kid"); }
+		/**
+		 * Get algorithm claim
+		 * \return algorithm as string
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a string (Should not happen in a valid token)
+		 */
+		const std::string& get_algorithm() const { return get_header_claim("alg").as_string(); }
+		/**
+		 * Get type claim
+		 * \return type as a string
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a string (Should not happen in a valid token)
+		 */
+		const std::string& get_type() const { return get_header_claim("typ").as_string(); }
+		/**
+		 * Get content type claim
+		 * \return content type as string
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a string (Should not happen in a valid token)
+		 */
+		const std::string& get_content_type() const { return get_header_claim("cty").as_string(); }
+		/**
+		 * Get key id claim
+		 * \return key id as string
+		 * \throws std::runtime_error If claim was not present
+		 * \throws std::bad_cast Claim was present but not a string (Should not happen in a valid token)
+		 */
+		const std::string& get_key_id() const { return get_header_claim("kid").as_string(); }
+		/**
+		 * Check if a header claim is present
+		 * \return true if claim was present, false otherwise
+		 */
+		bool has_header_claim(const std::string& name) const noexcept { return header_claims.count(name) != 0; }
+		/**
+		 * Get header claim
+		 * \return Requested claim
+		 * \throws std::runtime_error If claim was not present
+		 */
+		const claim& get_header_claim(const std::string& name) const {
+			if (!has_header_claim(name))
+				throw std::runtime_error("claim not found");
+			return header_claims.at(name);
+		}
+		/**
+		 * Get all header claims
+		 * \return map of claims
+		 */
+		std::unordered_map<std::string, claim> get_header_claims() const { return header_claims; }
+	};
+
+	/**
+	 * Class containing all information about a decoded token
+	 */
+	class decoded_jwt : public header, public payload {
+	protected:
+		/// Unmodifed token, as passed to constructor
+		const std::string token;
+		/// Header part decoded from base64
+		std::string header;
+		/// Unmodified header part in base64
+		std::string header_base64;
+		/// Payload part decoded from base64
+		std::string payload;
+		/// Unmodified payload part in base64
+		std::string payload_base64;
+		/// Signature part decoded from base64
+		std::string signature;
+		/// Unmodified signature part in base64
+		std::string signature_base64;
+	public:
+		/**
+		 * Constructor 
+		 * Parses a given token
+		 * \param token The token to parse
+		 * \throws std::invalid_argument Token is not in correct format
+		 * \throws std::runtime_error Base64 decoding failed or invalid json
+		 */
+		explicit decoded_jwt(const std::string& token)
+			: token(token)
+		{
+			auto hdr_end = token.find('.');
+			if (hdr_end == std::string::npos)
+				throw std::invalid_argument("invalid token supplied");
+			auto payload_end = token.find('.', hdr_end + 1);
+			if (payload_end == std::string::npos)
+				throw std::invalid_argument("invalid token supplied");
+			header = header_base64 = token.substr(0, hdr_end);
+			payload = payload_base64 = token.substr(hdr_end + 1, payload_end - hdr_end - 1);
+			signature = signature_base64 = token.substr(payload_end + 1);
+
+			// Fix padding: JWT requires padding to get removed
+			auto fix_padding = [](std::string& str) {
+				switch (str.size() % 4) {
+				case 1:
+					str += alphabet::base64url::fill();
+#ifdef __has_cpp_attribute
+#if __has_cpp_attribute(fallthrough)
+					[[fallthrough]];
+#endif
+#endif
+				case 2:
+					str += alphabet::base64url::fill();
+#ifdef __has_cpp_attribute
+#if __has_cpp_attribute(fallthrough)
+					[[fallthrough]];
+#endif
+#endif
+				case 3:
+					str += alphabet::base64url::fill();
+#ifdef __has_cpp_attribute
+#if __has_cpp_attribute(fallthrough)
+					[[fallthrough]];
+#endif
+#endif
+				default:
+					break;
+				}
+			};
+			fix_padding(header);
+			fix_padding(payload);
+			fix_padding(signature);
+
+			header = base::decode<alphabet::base64url>(header);
+			payload = base::decode<alphabet::base64url>(payload);
+			signature = base::decode<alphabet::base64url>(signature);
+
+			auto parse_claims = [](const std::string& str) {
+				std::unordered_map<std::string, claim> res;
+				picojson::value val;
+				if (!picojson::parse(val, str).empty())
+					throw std::runtime_error("Invalid json");
+
+				for (auto& e : val.get<picojson::object>()) { res.insert({ e.first, claim(e.second) }); }
+
+				return res;
+			};
+
+			header_claims = parse_claims(header);
+			payload_claims = parse_claims(payload);
+		}
+
+		/**
+		 * Get token string, as passed to constructor
+		 * \return token as passed to constructor
+		 */
+		const std::string& get_token() const noexcept { return token; }
+		/**
+		 * Get header part as json string
+		 * \return header part after base64 decoding
+		 */
+		const std::string& get_header() const noexcept { return header; }
+		/**
+		 * Get payload part as json string
+		 * \return payload part after base64 decoding
+		 */
+		const std::string& get_payload() const noexcept { return payload; }
+		/**
+		 * Get signature part as json string
+		 * \return signature part after base64 decoding
+		 */
+		const std::string& get_signature() const noexcept { return signature; }
+		/**
+		 * Get header part as base64 string
+		 * \return header part before base64 decoding
+		 */
+		const std::string& get_header_base64() const noexcept { return header_base64; }
+		/**
+		 * Get payload part as base64 string
+		 * \return payload part before base64 decoding
+		 */
+		const std::string& get_payload_base64() const noexcept { return payload_base64; }
+		/**
+		 * Get signature part as base64 string
+		 * \return signature part before base64 decoding
+		 */
+		const std::string& get_signature_base64() const noexcept { return signature_base64; }
+
+	};
+
+	/**
+	 * Builder class to build and sign a new token
+	 * Use jwt::create() to get an instance of this class.
+	 */
+	class builder {
+		std::unordered_map<std::string, claim> header_claims;
+		std::unordered_map<std::string, claim> payload_claims;
+
+		builder() {}
+		friend builder create();
+	public:
+		/**
+		 * Set a header claim.
+		 * \param id Name of the claim
+		 * \param c Claim to add
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_header_claim(const std::string& id, claim c) { header_claims[id] = std::move(c); return *this; }
+		/**
+		 * Set a payload claim.
+		 * \param id Name of the claim
+		 * \param c Claim to add
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_payload_claim(const std::string& id, claim c) { payload_claims[id] = std::move(c); return *this; }
+		/**
+		 * Set algorithm claim
+		 * You normally don't need to do this, as the algorithm is automatically set if you don't change it.
+		 * \param str Name of algorithm
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_algorithm(const std::string& str) { return set_header_claim("alg", claim(str)); }
+		/**
+		 * Set type claim
+		 * \param str Type to set
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_type(const std::string& str) { return set_header_claim("typ", claim(str)); }
+		/**
+		 * Set content type claim
+		 * \param str Type to set
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_content_type(const std::string& str) { return set_header_claim("cty", claim(str)); }
+		/**
+		 * Set key id claim
+		 * \param str Key id to set
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_key_id(const std::string& str) { return set_header_claim("kid", claim(str)); }
+		/**
+		 * Set issuer claim
+		 * \param str Issuer to set
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_issuer(const std::string& str) { return set_payload_claim("iss", claim(str)); }
+		/**
+		 * Set subject claim
+		 * \param str Subject to set
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_subject(const std::string& str) { return set_payload_claim("sub", claim(str)); }
+		/**
+		 * Set audience claim
+		 * \param l Audience set
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_audience(const std::set<std::string>& l) { return set_payload_claim("aud", claim(l)); }
+		/**
+		 * Set audience claim
+		 * \param aud Single audience
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_audience(const std::string& aud) { return set_payload_claim("aud", claim(aud)); }
+		/**
+		 * Set expires at claim
+		 * \param d Expires time
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_expires_at(const date& d) { return set_payload_claim("exp", claim(d)); }
+		/**
+		 * Set not before claim
+		 * \param d First valid time
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_not_before(const date& d) { return set_payload_claim("nbf", claim(d)); }
+		/**
+		 * Set issued at claim
+		 * \param d Issued at time, should be current time
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_issued_at(const date& d) { return set_payload_claim("iat", claim(d)); }
+		/**
+		 * Set id claim
+		 * \param str ID to set
+		 * \return *this to allow for method chaining
+		 */
+		builder& set_id(const std::string& str) { return set_payload_claim("jti", claim(str)); }
+
+		/**
+		 * Sign token and return result
+		 * \param algo Instance of an algorithm to sign the token with
+		 * \return Final token as a string
+		 */
+		template<typename T>
+		std::string sign(const T& algo) const {
+			picojson::object obj_header;
+			obj_header["alg"] = picojson::value(algo.name());
+			for (auto& e : header_claims) {
+				obj_header[e.first] = e.second.to_json();
+			}
+			picojson::object obj_payload;
+			for (auto& e : payload_claims) {
+				obj_payload.insert({ e.first, e.second.to_json() });
+			}
+
+			auto encode = [](const std::string& data) {
+				auto base = base::encode<alphabet::base64url>(data);
+				auto pos = base.find(alphabet::base64url::fill());
+				base = base.substr(0, pos);
+				return base;
+			};
+
+			std::string header = encode(picojson::value(obj_header).serialize());
+			std::string payload = encode(picojson::value(obj_payload).serialize());
+
+			std::string token = header + "." + payload;
+
+			return token + "." + encode(algo.sign(token));
+		}
+	};
+
+	/**
+	 * Verifier class used to check if a decoded token contains all claims required by your application and has a valid signature.
+	 */
+	template<typename Clock>
+	class verifier {
+		struct algo_base {
+			virtual ~algo_base() {}
+			virtual void verify(const std::string& data, const std::string& sig) = 0;
+		};
+		template<typename T>
+		struct algo : public algo_base {
+			T alg;
+			explicit algo(T a) : alg(a) {}
+			virtual void verify(const std::string& data, const std::string& sig) override {
+				alg.verify(data, sig);
+			}
+		};
+
+		/// Required claims
+		std::unordered_map<std::string, claim> claims;
+		/// Leeway time for exp, nbf and iat
+		size_t default_leeway = 0;
+		/// Instance of clock type
+		Clock clock;
+		/// Supported algorithms
+		std::unordered_map<std::string, std::shared_ptr<algo_base>> algs;
+	public:
+		/**
+		 * Constructor for building a new verifier instance
+		 * \param c Clock instance
+		 */
+		explicit verifier(Clock c) : clock(c) {}
+
+		/**
+		 * Set default leeway to use.
+		 * \param leeway Default leeway to use if not specified otherwise
+		 * \return *this to allow chaining
+		 */
+		verifier& leeway(size_t leeway) { default_leeway = leeway; return *this; }
+		/**
+		 * Set leeway for expires at.
+		 * If not specified the default leeway will be used.
+		 * \param leeway Set leeway to use for expires at.
+		 * \return *this to allow chaining
+		 */
+		verifier& expires_at_leeway(size_t leeway) { return with_claim("exp", claim(std::chrono::system_clock::from_time_t(leeway))); }
+		/**
+		 * Set leeway for not before.
+		 * If not specified the default leeway will be used.
+		 * \param leeway Set leeway to use for not before.
+		 * \return *this to allow chaining
+		 */
+		verifier& not_before_leeway(size_t leeway) { return with_claim("nbf", claim(std::chrono::system_clock::from_time_t(leeway))); }
+		/**
+		 * Set leeway for issued at.
+		 * If not specified the default leeway will be used.
+		 * \param leeway Set leeway to use for issued at.
+		 * \return *this to allow chaining
+		 */
+		verifier& issued_at_leeway(size_t leeway) { return with_claim("iat", claim(std::chrono::system_clock::from_time_t(leeway))); }
+		/**
+		 * Set an issuer to check for.
+		 * Check is casesensitive.
+		 * \param iss Issuer to check for.
+		 * \return *this to allow chaining
+		 */
+		verifier& with_issuer(const std::string& iss) { return with_claim("iss", claim(iss)); }
+		/**
+		 * Set a subject to check for.
+		 * Check is casesensitive.
+		 * \param sub Subject to check for.
+		 * \return *this to allow chaining
+		 */
+		verifier& with_subject(const std::string& sub) { return with_claim("sub", claim(sub)); }
+		/**
+		 * Set an audience to check for.
+		 * If any of the specified audiences is not present in the token the check fails.
+		 * \param aud Audience to check for.
+		 * \return *this to allow chaining
+		 */
+		verifier& with_audience(const std::set<std::string>& aud) { return with_claim("aud", claim(aud)); }
+		/**
+		 * Set an id to check for.
+		 * Check is casesensitive.
+		 * \param id ID to check for.
+		 * \return *this to allow chaining
+		 */
+		verifier& with_id(const std::string& id) { return with_claim("jti", claim(id)); }
+		/**
+		 * Specify a claim to check for.
+		 * \param name Name of the claim to check for
+		 * \param c Claim to check for
+		 * \return *this to allow chaining
+		 */
+		verifier& with_claim(const std::string& name, claim c) { claims[name] = c; return *this; }
+
+		/**
+		 * Add an algorithm available for checking.
+		 * \param alg Algorithm to allow
+		 * \return *this to allow chaining
+		 */
+		template<typename Algorithm>
+		verifier& allow_algorithm(Algorithm alg) {
+			algs[alg.name()] = std::make_shared<algo<Algorithm>>(alg);
+			return *this;
+		}
+
+		/**
+		 * Verify the given token.
+		 * \param jwt Token to check
+		 * \throws token_verification_exception Verification failed
+		 */
+		void verify(const decoded_jwt& jwt) const {
+			const std::string data = jwt.get_header_base64() + "." + jwt.get_payload_base64();
+			const std::string sig = jwt.get_signature();
+			const std::string& algo = jwt.get_algorithm();
+			if (algs.count(algo) == 0)
+				throw token_verification_exception("wrong algorithm");
+			algs.at(algo)->verify(data, sig);
+
+			auto assert_claim_eq = [](const decoded_jwt& jwt, const std::string& key, const claim& c) {
+				if (!jwt.has_payload_claim(key))
+					throw token_verification_exception("decoded_jwt is missing " + key + " claim");
+				auto& jc = jwt.get_payload_claim(key);
+				if (jc.get_type() != c.get_type())
+					throw token_verification_exception("claim " + key + " type mismatch");
+				if (c.get_type() == claim::type::int64) {
+					if (c.as_date() != jc.as_date())
+						throw token_verification_exception("claim " + key + " does not match expected");
+				}
+				else if (c.get_type() == claim::type::array) {
+					auto s1 = c.as_set();
+					auto s2 = jc.as_set();
+					if (s1.size() != s2.size())
+						throw token_verification_exception("claim " + key + " does not match expected");
+					auto it1 = s1.cbegin();
+					auto it2 = s2.cbegin();
+					while (it1 != s1.cend() && it2 != s2.cend()) {
+						if (*it1++ != *it2++)
+							throw token_verification_exception("claim " + key + " does not match expected");
+					}
+				}
+				else if (c.get_type() == claim::type::string) {
+					if (c.as_string() != jc.as_string())
+						throw token_verification_exception("claim " + key + " does not match expected");
+				}
+				else throw token_verification_exception("internal error");
+			};
+
+			auto time = clock.now();
+
+			if (jwt.has_expires_at()) {
+				auto leeway = claims.count("exp") == 1 ? std::chrono::system_clock::to_time_t(claims.at("exp").as_date()) : default_leeway;
+				auto exp = jwt.get_expires_at();
+				if (time > exp + std::chrono::seconds(leeway))
+					throw token_verification_exception("token expired");
+			}
+			if (jwt.has_issued_at()) {
+				auto leeway = claims.count("iat") == 1 ? std::chrono::system_clock::to_time_t(claims.at("iat").as_date()) : default_leeway;
+				auto iat = jwt.get_issued_at();
+				if (time < iat - std::chrono::seconds(leeway))
+					throw token_verification_exception("token expired");
+			}
+			if (jwt.has_not_before()) {
+				auto leeway = claims.count("nbf") == 1 ? std::chrono::system_clock::to_time_t(claims.at("nbf").as_date()) : default_leeway;
+				auto nbf = jwt.get_not_before();
+				if (time < nbf - std::chrono::seconds(leeway))
+					throw token_verification_exception("token expired");
+			}
+			for (auto& c : claims)
+			{
+				if (c.first == "exp" || c.first == "iat" || c.first == "nbf") {
+					// Nothing to do here, already checked
+				}
+				else if (c.first == "aud") {
+					if (!jwt.has_audience())
+						throw token_verification_exception("token doesn't contain the required audience");
+					auto aud = jwt.get_audience();
+					auto expected = c.second.as_set();
+					for (auto& e : expected)
+						if (aud.count(e) == 0)
+							throw token_verification_exception("token doesn't contain the required audience");
+				}
+				else {
+					assert_claim_eq(jwt, c.first, c.second);
+				}
+			}
+		}
+	};
+
+	/**
+	 * Create a verifier using the given clock
+	 * \param c Clock instance to use
+	 * \return verifier instance
+	 */
+	template<typename Clock>
+	verifier<Clock> verify(Clock c) {
+		return verifier<Clock>(c);
+	}
+
+	/**
+	 * Default clock class using std::chrono::system_clock as a backend.
+	 */
+	struct default_clock {
+		std::chrono::system_clock::time_point now() const {
+			return std::chrono::system_clock::now();
+		}
+	};
+
+	/**
+	 * Create a verifier using the default clock
+	 * \return verifier instance
+	 */
+    inline
+	verifier<default_clock> verify() {
+		return verify<default_clock>({});
+	}
+
+	/**
+	 * Return a builder instance to create a new token
+	 */
+    inline
+	builder create() {
+		return builder();
+	}
+
+	/**
+	 * Decode a token
+	 * \param token Token to decode
+	 * \return Decoded token
+	 * \throws std::invalid_argument Token is not in correct format
+	 * \throws std::runtime_error Base64 decoding failed or invalid json
+	 */
+    inline
+	decoded_jwt decode(const std::string& token) {
+		return decoded_jwt(token);
+	}
+}