crypto: implement RSA-2048-PSS

libraries/libvapours/include/vapours/crypto.hpp

@@ -19,4 +19,5 @@
 
 #include <vapours/crypto/crypto_memory_compare.hpp>
 #include <vapours/crypto/crypto_memory_clear.hpp>
-#include <vapours/crypto/impl/crypto_bignum.hpp>
+#include <vapours/crypto/crypto_sha256_generator.hpp>
+#include <vapours/crypto/crypto_rsa_pss_sha256_verifier.hpp>

libraries/libvapours/include/vapours/crypto/crypto_rsa_calculator.hpp

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+#include <vapours/util.hpp>
+#include <vapours/crypto/impl/crypto_bignum.hpp>
+
+namespace ams::crypto {
+
+    template<size_t ModulusSize, size_t ExponentSize>
+    class RsaCalculator {
+        NON_COPYABLE(RsaCalculator);
+        NON_MOVEABLE(RsaCalculator);
+        public:
+            static constexpr inline size_t RequiredWorkBufferSize = 0x10 * ModulusSize;
+        private:
+            impl::StaticBigNum<ModulusSize * BITSIZEOF(u8)> modulus;
+            impl::StaticBigNum<ExponentSize * BITSIZEOF(u8)> exponent;
+        public:
+            RsaCalculator() { /* ... */ }
+            ~RsaCalculator() { this->exponent.ClearToZero(); }
+
+            bool Initialize(const void *mod, size_t mod_size, const void *exp, size_t exp_size) {
+                if (!this->modulus.Import(mod, mod_size) || this->modulus.IsZero()) {
+                    return false;
+                }
+                if (!this->exponent.Import(exp, exp_size) || this->exponent.IsZero()) {
+                    return false;
+                }
+                return true;
+            }
+
+            bool ExpMod(void *dst, const void *src, size_t size, void *work_buf, size_t work_buf_size) {
+                AMS_ASSERT(work_buf_size >= RequiredWorkBufferSize);
+
+                return this->modulus.ExpMod(dst, src, size, this->exponent, static_cast<u32 *>(work_buf), work_buf_size);
+            }
+
+            bool ExpMod(void *dst, const void *src, size_t size) {
+                u32 work_buf[RequiredWorkBufferSize / sizeof(u32)];
+                return this->ExpMod(dst, src, size, work_buf, sizeof(work_buf));
+            }
+    };
+
+}

libraries/libvapours/include/vapours/crypto/crypto_rsa_pss_sha256_verifier.hpp

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+#include <vapours/util.hpp>
+#include <vapours/crypto/crypto_rsa_calculator.hpp>
+#include <vapours/crypto/crypto_rsa_pss_verifier.hpp>
+#include <vapours/crypto/crypto_sha256_generator.hpp>
+
+namespace ams::crypto {
+
+    namespace impl {
+
+        template<size_t Bits>
+        using RsaNPssSha256Verifier = ::ams::crypto::RsaPssVerifier<Bits / BITSIZEOF(u8), ::ams::crypto::Sha256Generator>;
+
+    }
+
+    using Rsa2048PssSha256Verifier = ::ams::crypto::impl::RsaNPssSha256Verifier<2048>;
+    using Rsa4096PssSha256Verifier = ::ams::crypto::impl::RsaNPssSha256Verifier<4096>;
+
+    inline bool VerifyRsa2048PssSha256(const void *sig, size_t sig_size, const void *mod, size_t mod_size, const void *exp, size_t exp_size, const void *msg, size_t msg_size) {
+        return Rsa2048PssSha256Verifier::Verify(sig, sig_size, mod, mod_size, exp, exp_size, msg, msg_size);
+    }
+
+    inline bool VerifyRsa2048PssSha256(const void *sig, size_t sig_size, const void *mod, size_t mod_size, const void *exp, size_t exp_size, const void *msg, size_t msg_size, void *work_buf, size_t work_buf_size) {
+        return Rsa2048PssSha256Verifier::Verify(sig, sig_size, mod, mod_size, exp, exp_size, msg, msg_size, work_buf, work_buf_size);
+    }
+
+    inline bool VerifyRsa4096PssSha256(const void *sig, size_t sig_size, const void *mod, size_t mod_size, const void *exp, size_t exp_size, const void *msg, size_t msg_size) {
+        return Rsa4096PssSha256Verifier::Verify(sig, sig_size, mod, mod_size, exp, exp_size, msg, msg_size);
+    }
+
+    inline bool VerifyRsa4096PssSha256(const void *sig, size_t sig_size, const void *mod, size_t mod_size, const void *exp, size_t exp_size, const void *msg, size_t msg_size, void *work_buf, size_t work_buf_size) {
+        return Rsa4096PssSha256Verifier::Verify(sig, sig_size, mod, mod_size, exp, exp_size, msg, msg_size, work_buf, work_buf_size);
+    }
+
+}

libraries/libvapours/include/vapours/crypto/crypto_rsa_pss_verifier.hpp

@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+#include <vapours/util.hpp>
+#include <vapours/crypto/crypto_rsa_calculator.hpp>
+#include <vapours/crypto/impl/crypto_rsa_pss_impl.hpp>
+
+namespace ams::crypto {
+
+    template<size_t ModulusSize, typename Hash> /* requires HashFunction<Hash> */
+    class RsaPssVerifier {
+        NON_COPYABLE(RsaPssVerifier);
+        NON_MOVEABLE(RsaPssVerifier);
+        public:
+            static constexpr size_t HashSize               = Hash::HashSize;
+            static constexpr size_t SaltSize               = Hash::HashSize;
+            static constexpr size_t SignatureSize          = ModulusSize;
+            static constexpr size_t MaximumExponentSize    = 3;
+            static constexpr size_t RequiredWorkBufferSize = RsaCalculator<ModulusSize, MaximumExponentSize>::RequiredWorkBufferSize;
+        private:
+            enum class State {
+                None,
+                Initialized,
+                Done,
+            };
+        private:
+            RsaCalculator<ModulusSize, MaximumExponentSize> calculator;
+            Hash hash;
+            State state;
+        public:
+            RsaPssVerifier() : state(State::None) { /* ... */ }
+            ~RsaPssVerifier() { }
+
+            bool Initialize(const void *mod, size_t mod_size, const void *exp, size_t exp_size) {
+                this->hash.Initialize();
+                if (this->calculator.Initialize(mod, mod_size, exp, exp_size)) {
+                    this->state = State::Initialized;
+                    return true;
+                } else {
+                    return false;
+                }
+            }
+
+            void Update(const void *data, size_t size) {
+                return this->hash.Update(data, size);
+            }
+
+            bool Verify(const void *signature, size_t size) {
+                AMS_ASSERT(this->state == State::Initialized);
+                AMS_ASSERT(size == SignatureSize);
+                ON_SCOPE_EXIT { this->state = State::Done; };
+
+                impl::RsaPssImpl<Hash> impl;
+                u8 message[SignatureSize];
+                ON_SCOPE_EXIT { ClearMemory(message, sizeof(message)); };
+
+                return this->calculator.ExpMod(message, signature, SignatureSize) &&
+                       impl.Verify(message, sizeof(message), std::addressof(this->hash));
+            }
+
+            bool Verify(const void *signature, size_t size, void *work_buf, size_t work_buf_size) {
+                AMS_ASSERT(this->state == State::Initialized);
+                AMS_ASSERT(size == SignatureSize);
+                ON_SCOPE_EXIT { this->state = State::Done; };
+
+                impl::RsaPssImpl<Hash> impl;
+                u8 message[SignatureSize];
+                ON_SCOPE_EXIT { ClearMemory(message, sizeof(message)); };
+
+                return this->calculator.ExpMod(message, signature, SignatureSize, work_buf, work_buf_size) &&
+                       impl.Verify(message, sizeof(message), std::addressof(this->hash));
+            }
+
+            static bool Verify(const void *sig, size_t sig_size, const void *mod, size_t mod_size, const void *exp, size_t exp_size, const void *msg, size_t msg_size) {
+                RsaPssVerifier<ModulusSize, Hash> verifier;
+                if (!verifier.Initialize(mod, mod_size, exp, exp_size)) {
+                    return false;
+                }
+                verifier.Update(msg, msg_size);
+                return verifier.Verify(sig, sig_size);
+            }
+
+            static bool Verify(const void *sig, size_t sig_size, const void *mod, size_t mod_size, const void *exp, size_t exp_size, const void *msg, size_t msg_size, void *work_buf, size_t work_buf_size) {
+                RsaPssVerifier<ModulusSize, Hash> verifier;
+                if (!verifier.Initialize(mod, mod_size, exp, exp_size)) {
+                    return false;
+                }
+                verifier.Update(msg, msg_size);
+                return verifier.Verify(sig, sig_size, work_buf, work_buf_size);
+            }
+    };
+
+}

libraries/libvapours/include/vapours/crypto/crypto_sha256_generator.hpp

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+#include <vapours/util.hpp>
+#include <vapours/crypto/impl/crypto_sha256_impl.hpp>
+
+namespace ams::crypto {
+
+    class Sha256Generator {
+        private:
+            using Impl = impl::Sha256Impl;
+        public:
+            static constexpr size_t HashSize  = Impl::HashSize;
+            static constexpr size_t BlockSize = Impl::BlockSize;
+
+            static constexpr inline u8 Asn1Identifier[] = {
+                0x30, 0x31, /* Sequence, size 0x31 */
+                    0x30, 0x0D, /* Sequence, size 0x0D */
+                        0x06, 0x09, /* Object Identifier */
+                            0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* SHA-256 */
+                        0x00, /* Null */
+                    0x04, 0x20, /* Octet string, size 0x20 */
+            };
+            static constexpr size_t Asn1IdentifierSize = util::size(Asn1Identifier);
+        private:
+            Impl impl;
+        public:
+            Sha256Generator() { /* ... */ }
+
+            void Initialize() {
+                this->impl.Initialize();
+            }
+
+            void Update(const void *data, size_t size) {
+                this->impl.Update(data, size);
+            }
+
+            void GetHash(void *dst, size_t size) {
+                this->impl.GetHash(dst, size);
+            }
+    };
+
+    void GenerateSha256Hash(void *dst, size_t dst_size, const void *src, size_t src_size);
+
+}

libraries/libvapours/include/vapours/crypto/impl/crypto_bignum.hpp

@@ -147,7 +147,7 @@ namespace ams::crypto::impl {
     };
 
     template<size_t Bits>
-    class StackBigNum : public BigNum {
+    class StaticBigNum : public BigNum {
         public:
             static constexpr size_t NumBits  = Bits;
             static constexpr size_t NumWords = util::AlignUp(NumBits, BitsPerWord) / BitsPerWord;
@@ -155,7 +155,7 @@ namespace ams::crypto::impl {
         private:
             Word word_buf[NumWords];
         public:
-            constexpr StackBigNum() : word_buf() {
+            constexpr StaticBigNum() : word_buf() {
                 this->ReserveStatic(word_buf, NumWords);
             }
     };

libraries/libvapours/include/vapours/crypto/impl/crypto_hash_function.hpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+#include <vapours/util.hpp>
+#include <vapours/crypto/crypto_memory_compare.hpp>
+#include <vapours/crypto/crypto_memory_clear.hpp>
+
+namespace ams::crypto::impl {
+
+    /* TODO: C++20
+        template<typename T>
+        concept HashFunction = requires(T &t, const void *cv, void *v, size_t sz) {
+            { T::HashSize      } -> std::same_as<size_t>;
+            { T::BlockSize     } -> std::same_as<size_t>;
+            { t.Initialize()   } -> std::same_as<void>;
+            { t.Update(cv, sz) } -> std::same_as<void>;
+            { t.GetHash(v, sz) } -> std::same_as<void>;
+        };
+    */
+
+}

libraries/libvapours/include/vapours/crypto/impl/crypto_rsa_pss_impl.hpp

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+#include <vapours/util.hpp>
+#include <vapours/crypto/impl/crypto_hash_function.hpp>
+
+namespace ams::crypto::impl {
+
+    template<typename Hash> /* requires HashFunction<Hash> */
+    class RsaPssImpl {
+        NON_COPYABLE(RsaPssImpl);
+        NON_MOVEABLE(RsaPssImpl);
+        public:
+            static constexpr size_t HashSize = Hash::HashSize;
+        private:
+            static constexpr u8 TailMagic = 0xBC;
+        private:
+            static void ComputeHashWithPadding(void *dst, Hash *hash, const void *salt, size_t salt_size) {
+                /* Initialize our buffer. */
+                u8 buf[8 + HashSize];
+                std::memset(buf, 0, 8);
+                hash->GetHash(buf + 8, HashSize);
+                ON_SCOPE_EXIT { ClearMemory(buf, sizeof(buf)); };
+
+
+                /* Calculate our hash. */
+                hash->Initialize();
+                hash->Update(buf, sizeof(buf));
+                hash->Update(salt, salt_size);
+                hash->GetHash(dst, HashSize);
+            }
+
+            static void ApplyMGF1(u8 *dst, size_t dst_size, const void *src, size_t src_size) {
+                u8 buf[HashSize];
+                ON_SCOPE_EXIT { ClearMemory(buf, sizeof(buf)); };
+
+                const size_t required_iters = (dst_size + HashSize - 1) / HashSize;
+                for (size_t i = 0; i < required_iters; i++) {
+                    Hash hash;
+                    hash.Initialize();
+                    hash.Update(src, src_size);
+
+                    const u32 tmp = util::ConvertToBigEndian(static_cast<u32>(i));
+                    hash.Update(std::addressof(tmp), sizeof(tmp));
+
+                    hash.GetHash(buf, HashSize);
+
+                    const size_t start = HashSize * i;
+                    const size_t end   = std::min(dst_size, start + HashSize);
+                    for (size_t j = start; j < end; j++) {
+                        dst[j] ^= buf[j - start];
+                    }
+                }
+            }
+        public:
+            RsaPssImpl() { /* ... */ }
+
+            bool Verify(u8 *buf, size_t size, Hash *hash) {
+                /* Validate sanity byte. */
+                if (buf[size - 1] != TailMagic) {
+                    return false;
+                }
+
+                /* Decrypt maskedDB */
+                const size_t db_len = size - HashSize - 1;
+                u8 *db = buf;
+                u8 *h  = db + db_len;
+                ApplyMGF1(db, db_len, h, HashSize);
+
+                /* Apply lmask. */
+                db[0] &= 0x7F;
+
+                /* Verify that DB is of the form 0000...0001 */
+                s32 salt_ofs = -1;
+                for (size_t i = 0; i < db_len; i++) {
+                    if (db[i] != 0) {
+                        salt_ofs = static_cast<s32>(i) + 1;
+                        break;
+                    }
+                }
+                if (salt_ofs == -1) {
+                    return false;
+                }
+                if (db[salt_ofs - 1] != 1) {
+                    return false;
+                }
+
+                /* Verify salt. */
+                const u8 *salt = db + salt_ofs;
+                const size_t salt_size = db_len - salt_ofs;
+                if (salt_size == 0) {
+                    return false;
+                }
+
+                /* Verify hash. */
+                u8 cmp_hash[HashSize];
+                ON_SCOPE_EXIT { ClearMemory(cmp_hash, sizeof(cmp_hash)); };
+
+                ComputeHashWithPadding(cmp_hash, hash, salt, salt_size);
+                return IsSameBytes(cmp_hash, h, HashSize);
+            }
+    };
+
+}

libraries/libvapours/include/vapours/crypto/impl/crypto_sha256_impl.hpp

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+#include <vapours/util.hpp>
+#include <vapours/crypto/impl/crypto_hash_function.hpp>
+#include <vapours/crypto/crypto_memory_clear.hpp>
+
+namespace ams::crypto::impl {
+
+    class Sha256Impl {
+        public:
+            static constexpr size_t HashSize  = 0x20;
+            static constexpr size_t BlockSize = 0x40;
+        private:
+            struct State {
+                u32 intermediate_hash[HashSize / sizeof(u32)];
+                u8  buffer[BlockSize];
+                u64 bits_consumed;
+                size_t num_buffered;
+                bool finalized;
+            };
+        private:
+            State state;
+        public:
+            Sha256Impl() { /* ... */ }
+            ~Sha256Impl() {
+                static_assert(std::is_trivially_destructible<State>::value);
+                ClearMemory(std::addressof(this->state), sizeof(this->state));
+            }
+
+            void Initialize();
+            void Update(const void *data, size_t size);
+            void GetHash(void *dst, size_t size);
+    };
+
+    /* static_assert(HashFunction<Sha256Impl>); */
+
+}

libraries/libvapours/include/vapours/util.hpp

@@ -20,6 +20,7 @@
 
 #include <vapours/util/util_alignment.hpp>
 #include <vapours/util/util_size.hpp>
+#include <vapours/util/util_endian.hpp>
 #include <vapours/util/util_fourcc.hpp>
 #include <vapours/util/util_bitpack.hpp>
 #include <vapours/util/util_bitset.hpp>

libraries/libvapours/include/vapours/util/util_endian.hpp

@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <vapours/common.hpp>
+#include <vapours/assert.hpp>
+
+namespace ams::util {
+
+    /* TODO: C++20 std::endian */
+
+    constexpr bool IsLittleEndian() {
+        #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+            return true;
+        #else
+            return false;
+        #endif
+    }
+
+    constexpr bool IsBigEndian() {
+        #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+            return true;
+        #else
+            return false;
+        #endif
+    }
+
+    static_assert(IsLittleEndian() ^ IsBigEndian());
+
+    template<typename U> /* requires unsigned_integral<U> */
+    constexpr ALWAYS_INLINE U SwapBytes(const U u) {
+        static_assert(BITSIZEOF(u8) == 8);
+        constexpr U ByteMask = 0xFFu;
+        if constexpr (std::is_same<U, u64>::value) {
+            return  ((u & (ByteMask << 56)) >> 56) |
+                    ((u & (ByteMask << 48)) >> 40) |
+                    ((u & (ByteMask << 40)) >> 24) |
+                    ((u & (ByteMask << 32)) >>  8) |
+                    ((u & (ByteMask << 24)) <<  8) |
+                    ((u & (ByteMask << 16)) << 24) |
+                    ((u & (ByteMask <<  8)) << 40) |
+                    ((u & (ByteMask <<  0)) << 56);
+
+        } else if constexpr (std::is_same<U, u32>::value) {
+            return  ((u & (ByteMask << 24)) >> 24) |
+                    ((u & (ByteMask << 16)) >>  8) |
+                    ((u & (ByteMask <<  8)) <<  8) |
+                    ((u & (ByteMask <<  0)) << 24);
+
+        } else if constexpr (std::is_same<U, u16>::value) {
+            return  ((u & (ByteMask << 8)) >> 8) |
+                    ((u & (ByteMask << 0)) << 8);
+
+        } else if constexpr (std::is_same<U, u8>::value) {
+            return u;
+        } else {
+            static_assert(!std::is_same<U, U>::value);
+        }
+    }
+
+    template<typename T> /* requires integral<T> */
+    constexpr ALWAYS_INLINE void SwapBytes(T *ptr) {
+        using U = typename std::make_unsigned<T>::type;
+
+        *ptr = static_cast<T>(SwapBytes(static_cast<U>(*ptr)));
+    }
+
+    template<typename T>
+    constexpr ALWAYS_INLINE T ConvertToBigEndian(const T val) {
+        if constexpr (IsBigEndian()) {
+            return val;
+        } else {
+            static_assert(IsLittleEndian());
+            return SwapBytes(val);
+        }
+    }
+
+    template<typename T>
+    constexpr ALWAYS_INLINE T ConvertToLittleEndian(const T val) {
+        if constexpr (IsBigEndian()) {
+            return SwapBytes(val);
+        } else {
+            static_assert(IsLittleEndian());
+            return val;
+        }
+    }
+
+    template<typename T> /* requires integral<T> */
+    constexpr ALWAYS_INLINE T LoadBigEndian(T *ptr) {
+        return ConvertToBigEndian(*ptr);
+    }
+
+    template<typename T> /* requires integral<T> */
+    constexpr ALWAYS_INLINE T LoadLittleEndian(T *ptr) {
+        return ConvertToLittleEndian(*ptr);
+    }
+
+    template<typename T>
+    constexpr ALWAYS_INLINE void StoreBigEndian(T *ptr, T val) {
+        *ptr = ConvertToBigEndian(val);
+    }
+
+    template<typename T>
+    constexpr ALWAYS_INLINE void StoreLittleEndian(T *ptr, T val) {
+        *ptr = ConvertToLittleEndian(val);
+    }
+
+}

libraries/libvapours/source/crypto/crypto_sha256_generator.cpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <vapours.hpp>
+
+namespace ams::crypto {
+
+    void GenerateSha256Hash(void *dst, size_t dst_size, const void *src, size_t src_size) {
+        Sha256Generator gen;
+
+        gen.Initialize();
+        gen.Update(src, src_size);
+        gen.GetHash(dst, dst_size);
+    }
+
+}

libraries/libvapours/source/crypto/impl/crypto_sha256_impl.arch.arm64.cpp

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <vapours.hpp>
+
+namespace ams::crypto::impl {
+
+#ifdef ATMOSPHERE_IS_STRATOSPHERE
+
+    void Sha256Impl::Initialize() {
+        static_assert(sizeof(this->state) == sizeof(::Sha256Context));
+        ::sha256ContextCreate(reinterpret_cast<::Sha256Context *>(std::addressof(this->state)));
+    }
+
+    void Sha256Impl::Update(const void *data, size_t size) {
+        static_assert(sizeof(this->state) == sizeof(::Sha256Context));
+        ::sha256ContextUpdate(reinterpret_cast<::Sha256Context *>(std::addressof(this->state)), data, size);
+    }
+
+    void Sha256Impl::GetHash(void *dst, size_t size) {
+        static_assert(sizeof(this->state) == sizeof(::Sha256Context));
+        AMS_ASSERT(size >= HashSize);
+        ::sha256ContextGetHash(reinterpret_cast<::Sha256Context *>(std::addressof(this->state)), dst);
+    }
+
+#else
+
+    /* TODO: Non-EL0 implementation. */
+
+#endif
+
+}