LibCrypto: Move Curve25519 related code into separate file

3 files changed, 465 insertions, 267 deletions

diff --git a/Userland/Libraries/LibCrypto/Curves/Curve25519.cpp b/Userland/Libraries/LibCrypto/Curves/Curve25519.cpp
new file mode 100644
index 0000000000..5651598ae1
--- /dev/null
+++ b/Userland/Libraries/LibCrypto/Curves/Curve25519.cpp
@@ -0,0 +1,360 @@
+/*
+ * Copyright (c) 2022, stelar7 <dudedbz@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Endian.h>
+#include <AK/Types.h>
+#include <LibCrypto/Curves/Curve25519.h>
+
+namespace Crypto::Curves {
+
+void Curve25519::set(u32* state, u32 value)
+{
+    state[0] = value;
+
+    for (auto i = 1; i < WORDS; i++) {
+        state[i] = 0;
+    }
+}
+
+void Curve25519::modular_square(u32* state, u32 const* value)
+{
+    // Compute R = (A ^ 2) mod p
+    modular_multiply(state, value, value);
+}
+
+void Curve25519::modular_subtract(u32* state, u32 const* first, u32 const* second)
+{
+    // R = (A - B) mod p
+    i64 temp = -19;
+    for (auto i = 0; i < WORDS; i++) {
+        temp += first[i];
+        temp -= second[i];
+        state[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    // Compute R = A + (2^255 - 19) - B
+    state[7] += 0x80000000;
+
+    modular_reduce(state, state);
+}
+
+void Curve25519::modular_add(u32* state, u32 const* first, u32 const* second)
+{
+    // R = (A + B) mod p
+    u64 temp = 0;
+    for (auto i = 0; i < WORDS; i++) {
+        temp += first[i];
+        temp += second[i];
+        state[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    modular_reduce(state, state);
+}
+
+void Curve25519::modular_multiply(u32* state, u32 const* first, u32 const* second)
+{
+    // Compute R = (A * B) mod p
+    u64 temp = 0;
+    u64 carry = 0;
+    u32 output[WORDS * 2];
+
+    // Comba's method
+    for (auto i = 0; i < 16; i++) {
+        if (i < WORDS) {
+            for (auto j = 0; j <= i; j++) {
+                temp += (u64)first[j] * second[i - j];
+                carry += temp >> 32;
+                temp &= 0xFFFFFFFF;
+            }
+        } else {
+            for (auto j = i - 7; j < WORDS; j++) {
+                temp += (u64)first[j] * second[i - j];
+                carry += temp >> 32;
+                temp &= 0xFFFFFFFF;
+            }
+        }
+
+        output[i] = temp & 0xFFFFFFFF;
+        temp = carry & 0xFFFFFFFF;
+        carry >>= 32;
+    }
+
+    // Reduce bit 255 (2^255 = 19 mod p)
+    temp = (output[7] >> 31) * 19;
+    // Mask the most significant bit
+    output[7] &= 0x7FFFFFFF;
+
+    // Fast modular reduction 1st pass
+    for (auto i = 0; i < WORDS; i++) {
+        temp += output[i];
+        temp += (u64)output[i + 8] * 38;
+        output[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    // Reduce bit 256 (2^256 = 38 mod p)
+    temp *= 38;
+    // Reduce bit 255 (2^255 = 19 mod p)
+    temp += (output[7] >> 31) * 19;
+    // Mask the most significant bit
+    output[7] &= 0x7FFFFFFF;
+
+    // Fast modular reduction 2nd pass
+    for (auto i = 0; i < WORDS; i++) {
+        temp += output[i];
+        output[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    modular_reduce(state, output);
+}
+
+void Curve25519::export_state(u32* state, u8* output)
+{
+    for (u32 i = 0; i < WORDS; i++) {
+        state[i] = AK::convert_between_host_and_little_endian(state[i]);
+    }
+
+    memcpy(output, state, BYTES);
+}
+
+void Curve25519::import_state(u32* state, u8 const* data)
+{
+    memcpy(state, data, BYTES);
+    for (u32 i = 0; i < WORDS; i++) {
+        state[i] = AK::convert_between_host_and_little_endian(state[i]);
+    }
+}
+
+void Curve25519::modular_subtract_single(u32* r, u32 const* a, u32 b)
+{
+    i64 temp = -19;
+    temp -= b;
+
+    // Compute R = A - 19 - B
+    for (u32 i = 0; i < 8; i++) {
+        temp += a[i];
+        r[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    // Compute R = A + (2^255 - 19) - B
+    r[7] += 0x80000000;
+    modular_reduce(r, r);
+}
+
+void Curve25519::modular_add_single(u32* state, u32 const* first, u32 second)
+{
+    u64 temp = second;
+
+    // Compute R = A + B
+    for (u32 i = 0; i < 8; i++) {
+        temp += first[i];
+        state[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    modular_reduce(state, state);
+}
+
+u32 Curve25519::modular_square_root(u32* r, u32 const* a, u32 const* b)
+{
+    u32 c[8];
+    u32 u[8];
+    u32 v[8];
+
+    // To compute the square root of (A / B), the first step is to compute the candidate root x = (A / B)^((p+3)/8)
+    modular_square(v, b);
+    modular_multiply(v, v, b);
+    modular_square(v, v);
+    modular_multiply(v, v, b);
+    modular_multiply(c, a, v);
+    modular_square(u, c);
+    modular_multiply(u, u, c);
+    modular_square(u, u);
+    modular_multiply(v, u, c);
+    to_power_of_2n(u, v, 3);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, c);
+    to_power_of_2n(u, v, 7);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, c);
+    to_power_of_2n(u, v, 15);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, c);
+    to_power_of_2n(u, v, 31);
+    modular_multiply(v, u, v);
+    to_power_of_2n(u, v, 62);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, c);
+    to_power_of_2n(u, v, 125);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_square(u, u);
+    modular_multiply(u, u, c);
+
+    // The first candidate root is U = A * B^3 * (A * B^7)^((p - 5) / 8)
+    modular_multiply(u, u, a);
+    modular_square(v, b);
+    modular_multiply(v, v, b);
+    modular_multiply(u, u, v);
+
+    // The second candidate root is V = U * sqrt(-1)
+    modular_multiply(v, u, SQRT_MINUS_1);
+
+    modular_square(c, u);
+    modular_multiply(c, c, b);
+
+    // Check whether B * U^2 = A
+    u32 first_comparison = compare(c, a);
+
+    modular_square(c, v);
+    modular_multiply(c, c, b);
+
+    // Check whether B * V^2 = A
+    u32 second_comparison = compare(c, a);
+
+    // Select the first or the second candidate root
+    select(r, u, v, first_comparison);
+
+    // Return 0 if the square root exists
+    return first_comparison & second_comparison;
+}
+
+u32 Curve25519::compare(u32 const* a, u32 const* b)
+{
+    u32 mask = 0;
+    for (u32 i = 0; i < 8; i++) {
+        mask |= a[i] ^ b[i];
+    }
+
+    // Return 0 if A = B, else 1
+    return ((u32)(mask | (~mask + 1))) >> 31;
+}
+
+void Curve25519::modular_reduce(u32* state, u32 const* data)
+{
+    // R = A mod p
+    u64 temp = 19;
+    u32 other[WORDS];
+
+    for (auto i = 0; i < WORDS; i++) {
+        temp += data[i];
+        other[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    // Compute B = A - (2^255 - 19)
+    other[7] -= 0x80000000;
+
+    u32 mask = (other[7] & 0x80000000) >> 31;
+    select(state, other, data, mask);
+}
+
+void Curve25519::to_power_of_2n(u32* state, u32 const* value, u8 n)
+{
+    // Pre-compute (A ^ 2) mod p
+    modular_square(state, value);
+
+    // Compute R = (A ^ (2^n)) mod p
+    for (u32 i = 1; i < n; i++) {
+        modular_square(state, state);
+    }
+}
+
+void Curve25519::select(u32* state, u32 const* a, u32 const* b, u32 condition)
+{
+    // If B < (2^255 - 19) then R = B, else R = A
+    u32 mask = condition - 1;
+
+    for (auto i = 0; i < WORDS; i++) {
+        state[i] = (a[i] & mask) | (b[i] & ~mask);
+    }
+}
+
+void Curve25519::copy(u32* state, u32 const* value)
+{
+    for (auto i = 0; i < WORDS; i++) {
+        state[i] = value[i];
+    }
+}
+
+void Curve25519::modular_multiply_inverse(u32* state, u32 const* value)
+{
+    // Compute R = A^-1 mod p
+    u32 u[WORDS];
+    u32 v[WORDS];
+
+    // Fermat's little theorem
+    modular_square(u, value);
+    modular_multiply(u, u, value);
+    modular_square(u, u);
+    modular_multiply(v, u, value);
+    to_power_of_2n(u, v, 3);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, value);
+    to_power_of_2n(u, v, 7);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, value);
+    to_power_of_2n(u, v, 15);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, value);
+    to_power_of_2n(u, v, 31);
+    modular_multiply(v, u, v);
+    to_power_of_2n(u, v, 62);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_multiply(v, u, value);
+    to_power_of_2n(u, v, 125);
+    modular_multiply(u, u, v);
+    modular_square(u, u);
+    modular_square(u, u);
+    modular_multiply(u, u, value);
+    modular_square(u, u);
+    modular_square(u, u);
+    modular_multiply(u, u, value);
+    modular_square(u, u);
+    modular_multiply(state, u, value);
+}
+
+void Curve25519::modular_multiply_single(u32* state, u32 const* first, u32 second)
+{
+    // Compute R = (A * B) mod p
+    u64 temp = 0;
+    u32 output[WORDS];
+
+    for (auto i = 0; i < WORDS; i++) {
+        temp += (u64)first[i] * second;
+        output[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    // Reduce bit 256 (2^256 = 38 mod p)
+    temp *= 38;
+    // Reduce bit 255 (2^255 = 19 mod p)
+    temp += (output[7] >> 31) * 19;
+    // Mask the most significant bit
+    output[7] &= 0x7FFFFFFF;
+
+    // Fast modular reduction
+    for (auto i = 0; i < WORDS; i++) {
+        temp += output[i];
+        output[i] = temp & 0xFFFFFFFF;
+        temp >>= 32;
+    }
+
+    modular_reduce(state, output);
+}
+}
diff --git a/Userland/Libraries/LibCrypto/Curves/Curve25519.h b/Userland/Libraries/LibCrypto/Curves/Curve25519.h
new file mode 100644
index 0000000000..eb4d32e0de
--- /dev/null
+++ b/Userland/Libraries/LibCrypto/Curves/Curve25519.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2022, stelar7 <dudedbz@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Random.h>
+
+namespace Crypto::Curves {
+
+class Curve25519 {
+public:
+    static constexpr u8 BASE_POINT_L_ORDER[33] {
+        0xED, 0xD3, 0xF5, 0x5C, 0x1A, 0x63, 0x12, 0x58,
+        0xD6, 0x9C, 0xF7, 0xA2, 0xDE, 0xF9, 0xDE, 0x14,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
+        0x00
+    };
+
+    static constexpr u32 CURVE_D[8] {
+        0x135978A3, 0x75EB4DCA, 0x4141D8AB, 0x00700A4D,
+        0x7779E898, 0x8CC74079, 0x2B6FFE73, 0x52036CEE
+    };
+
+    static constexpr u32 CURVE_D_2[8] {
+        0x26B2F159, 0xEBD69B94, 0x8283B156, 0x00E0149A,
+        0xEEF3D130, 0x198E80F2, 0x56DFFCE7, 0x2406D9DC
+    };
+
+    static constexpr u32 ZERO[8] {
+        0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000
+    };
+
+    static constexpr u32 SQRT_MINUS_1[8] {
+        0x4A0EA0B0, 0xC4EE1B27, 0xAD2FE478, 0x2F431806,
+        0x3DFBD7A7, 0x2B4D0099, 0x4FC1DF0B, 0x2B832480
+    };
+
+    static constexpr u8 BARRETT_REDUCTION_QUOTIENT[33] {
+        0x1B, 0x13, 0x2C, 0x0A, 0xA3, 0xE5, 0x9C, 0xED,
+        0xA7, 0x29, 0x63, 0x08, 0x5D, 0x21, 0x06, 0x21,
+        0xEB, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+        0x0F
+    };
+
+    static constexpr u8 BITS = 255;
+    static constexpr u8 BYTES = 32;
+    static constexpr u8 WORDS = 8;
+    static constexpr u32 A24 = 121666;
+
+    static void set(u32* a, u32 b);
+    static void select(u32* r, u32 const* a, u32 const* b, u32 c);
+    static void copy(u32* a, u32 const* b);
+    static void modular_square(u32* r, u32 const* a);
+    static void modular_subtract(u32* r, u32 const* a, u32 const* b);
+    static void modular_reduce(u32* r, u32 const* a);
+    static void modular_add(u32* r, u32 const* a, u32 const* b);
+    static void modular_multiply(u32* r, u32 const* a, u32 const* b);
+    static void modular_multiply_inverse(u32* r, u32 const* a);
+    static void to_power_of_2n(u32* r, u32 const* a, u8 n);
+    static void export_state(u32* a, u8* data);
+    static void import_state(u32* a, u8 const* data);
+    static void modular_subtract_single(u32* r, u32 const* a, u32 b);
+    static void modular_multiply_single(u32* r, u32 const* a, u32 b);
+    static void modular_add_single(u32* r, u32 const* a, u32 b);
+    static u32 modular_square_root(u32* r, u32 const* a, u32 const* b);
+    static u32 compare(u32 const* a, u32 const* b);
+};
+}
diff --git a/Userland/Libraries/LibCrypto/Curves/X25519.cpp b/Userland/Libraries/LibCrypto/Curves/X25519.cpp
index faa98f4e8b..07c2ffd300 100644
--- a/Userland/Libraries/LibCrypto/Curves/X25519.cpp
+++ b/Userland/Libraries/LibCrypto/Curves/X25519.cpp
@@ -7,6 +7,7 @@
 #include <AK/ByteReader.h>
 #include <AK/Endian.h>
 #include <AK/Random.h>
+#include <LibCrypto/Curves/Curve25519.h>
 #include <LibCrypto/Curves/X25519.h>
 
 namespace Crypto::Curves {
@@ -16,52 +17,6 @@ static constexpr u8 BYTES = 32;
 static constexpr u8 WORDS = 8;
 static constexpr u32 A24 = 121666;
 
-static void import_state(u32* state, ReadonlyBytes data)
-{
-    for (auto i = 0; i < WORDS; i++) {
-        u32 value = ByteReader::load32(data.offset_pointer(sizeof(u32) * i));
-        state[i] = AK::convert_between_host_and_little_endian(value);
-    }
-}
-
-static ErrorOr<ByteBuffer> export_state(u32* data)
-{
-    auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
-
-    for (auto i = 0; i < WORDS; i++) {
-        u32 value = AK::convert_between_host_and_little_endian(data[i]);
-        ByteReader::store(buffer.offset_pointer(sizeof(u32) * i), value);
-    }
-
-    return buffer;
-}
-
-static void select(u32* state, u32* a, u32* b, u32 condition)
-{
-    // If B < (2^255 - 19) then R = B, else R = A
-    u32 mask = condition - 1;
-
-    for (auto i = 0; i < WORDS; i++) {
-        state[i] = (a[i] & mask) | (b[i] & ~mask);
-    }
-}
-
-static void set(u32* state, u32 value)
-{
-    state[0] = value;
-
-    for (auto i = 1; i < WORDS; i++) {
-        state[i] = 0;
-    }
-}
-
-static void copy(u32* state, u32* value)
-{
-    for (auto i = 0; i < WORDS; i++) {
-        state[i] = value[i];
-    }
-}
-
 static void conditional_swap(u32* first, u32* second, u32 condition)
 {
     u32 mask = ~condition + 1;
@@ -72,199 +27,6 @@ static void conditional_swap(u32* first, u32* second, u32 condition)
     }
 }
 
-static void modular_reduce(u32* state, u32* data)
-{
-    // R = A mod p
-    u64 temp = 19;
-    u32 other[WORDS];
-
-    for (auto i = 0; i < WORDS; i++) {
-        temp += data[i];
-        other[i] = temp & 0xFFFFFFFF;
-        temp >>= 32;
-    }
-
-    // Compute B = A - (2^255 - 19)
-    other[7] -= 0x80000000;
-
-    u32 mask = (other[7] & 0x80000000) >> 31;
-    select(state, other, data, mask);
-}
-
-static void modular_multiply_single(u32* state, u32* first, u32 second)
-{
-    // Compute R = (A * B) mod p
-    u64 temp = 0;
-    u32 output[WORDS];
-
-    for (auto i = 0; i < WORDS; i++) {
-        temp += (u64)first[i] * second;
-        output[i] = temp & 0xFFFFFFFF;
-        temp >>= 32;
-    }
-
-    // Reduce bit 256 (2^256 = 38 mod p)
-    temp *= 38;
-    // Reduce bit 255 (2^255 = 19 mod p)
-    temp += (output[7] >> 31) * 19;
-    // Mask the most significant bit
-    output[7] &= 0x7FFFFFFF;
-
-    // Fast modular reduction
-    for (auto i = 0; i < WORDS; i++) {
-        temp += output[i];
-        output[i] = temp & 0xFFFFFFFF;
-        temp >>= 32;
-    }
-
-    modular_reduce(state, output);
-}
-
-static void modular_multiply(u32* state, u32* first, u32* second)
-{
-    // Compute R = (A * B) mod p
-    u64 temp = 0;
-    u64 carry = 0;
-    u32 output[WORDS * 2];
-
-    // Comba's method
-    for (auto i = 0; i < 16; i++) {
-        if (i < WORDS) {
-            for (auto j = 0; j <= i; j++) {
-                temp += (u64)first[j] * second[i - j];
-                carry += temp >> 32;
-                temp &= 0xFFFFFFFF;
-            }
-        } else {
-            for (auto j = i - 7; j < WORDS; j++) {
-                temp += (u64)first[j] * second[i - j];
-                carry += temp >> 32;
-                temp &= 0xFFFFFFFF;
-            }
-        }
-
-        output[i] = temp & 0xFFFFFFFF;
-        temp = carry & 0xFFFFFFFF;
-        carry >>= 32;
-    }
-
-    // Reduce bit 255 (2^255 = 19 mod p)
-    temp = (output[7] >> 31) * 19;
-    // Mask the most significant bit
-    output[7] &= 0x7FFFFFFF;
-
-    // Fast modular reduction 1st pass
-    for (auto i = 0; i < WORDS; i++) {
-        temp += output[i];
-        temp += (u64)output[i + 8] * 38;
-        output[i] = temp & 0xFFFFFFFF;
-        temp >>= 32;
-    }
-
-    // Reduce bit 256 (2^256 = 38 mod p)
-    temp *= 38;
-    // Reduce bit 255 (2^255 = 19 mod p)
-    temp += (output[7] >> 31) * 19;
-    // Mask the most significant bit
-    output[7] &= 0x7FFFFFFF;
-
-    // Fast modular reduction 2nd pass
-    for (auto i = 0; i < WORDS; i++) {
-        temp += output[i];
-        output[i] = temp & 0xFFFFFFFF;
-        temp >>= 32;
-    }
-
-    modular_reduce(state, output);
-}
-
-static void modular_square(u32* state, u32* value)
-{
-    // Compute R = (A ^ 2) mod p
-    modular_multiply(state, value, value);
-}
-
-static void modular_add(u32* state, u32* first, u32* second)
-{
-    // R = (A + B) mod p
-    u64 temp = 0;
-    for (auto i = 0; i < WORDS; i++) {
-        temp += first[i];
-        temp += second[i];
-        state[i] = temp & 0xFFFFFFFF;
-        temp >>= 32;
-    }
-
-    modular_reduce(state, state);
-}
-
-static void modular_subtract(u32* state, u32* first, u32* second)
-{
-    // R = (A - B) mod p
-    i64 temp = -19;
-    for (auto i = 0; i < WORDS; i++) {
-        temp += first[i];
-        temp -= second[i];
-        state[i] = temp & 0xFFFFFFFF;
-        temp >>= 32;
-    }
-
-    // Compute R = A + (2^255 - 19) - B
-    state[7] += 0x80000000;
-
-    modular_reduce(state, state);
-}
-
-static void to_power_of_2n(u32* state, u32* value, u8 n)
-{
-    // compute R = (A ^ (2^n)) mod p
-    modular_square(state, value);
-    for (auto i = 1; i < n; i++) {
-        modular_square(state, state);
-    }
-}
-
-static void modular_multiply_inverse(u32* state, u32* value)
-{
-    // Compute R = A^-1 mod p
-    u32 u[WORDS];
-    u32 v[WORDS];
-
-    // Fermat's little theorem
-    modular_square(u, value);
-    modular_multiply(u, u, value);
-    modular_square(u, u);
-    modular_multiply(v, u, value);
-    to_power_of_2n(u, v, 3);
-    modular_multiply(u, u, v);
-    modular_square(u, u);
-    modular_multiply(v, u, value);
-    to_power_of_2n(u, v, 7);
-    modular_multiply(u, u, v);
-    modular_square(u, u);
-    modular_multiply(v, u, value);
-    to_power_of_2n(u, v, 15);
-    modular_multiply(u, u, v);
-    modular_square(u, u);
-    modular_multiply(v, u, value);
-    to_power_of_2n(u, v, 31);
-    modular_multiply(v, u, v);
-    to_power_of_2n(u, v, 62);
-    modular_multiply(u, u, v);
-    modular_square(u, u);
-    modular_multiply(v, u, value);
-    to_power_of_2n(u, v, 125);
-    modular_multiply(u, u, v);
-    modular_square(u, u);
-    modular_square(u, u);
-    modular_multiply(u, u, value);
-    modular_square(u, u);
-    modular_square(u, u);
-    modular_multiply(u, u, value);
-    modular_square(u, u);
-    modular_multiply(state, u, value);
-}
-
 ErrorOr<ByteBuffer> X25519::generate_private_key()
 {
     auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
@@ -291,7 +53,7 @@ ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBy
     u32 t2[WORDS] {};
 
     // Copy input to internal state
-    import_state(k, input_k);
+    Curve25519::import_state(k, input_k.data());
 
     // Set the three least significant bits of the first byte and the most significant bit of the last to zero,
     // set the second most significant bit of the last byte to 1
@@ -300,18 +62,18 @@ ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBy
     k[7] |= 0x40000000;
 
     // Copy coordinate to internal state
-    import_state(u, input_u);
+    Curve25519::import_state(u, input_u.data());
     // mask the most significant bit in the final byte.
     u[7] &= 0x7FFFFFFF;
 
     // Implementations MUST accept non-canonical values and process them as
     // if they had been reduced modulo the field prime.
-    modular_reduce(u, u);
+    Curve25519::modular_reduce(u, u);
 
-    set(x1, 1);
-    set(z1, 0);
-    copy(x2, u);
-    set(z2, 1);
+    Curve25519::set(x1, 1);
+    Curve25519::set(z1, 0);
+    Curve25519::copy(x2, u);
+    Curve25519::set(z2, 1);
 
     // Montgomery ladder
     u32 swap = 0;
@@ -323,35 +85,38 @@ ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBy
 
         swap = b;
 
-        modular_add(t1, x2, z2);
-        modular_subtract(x2, x2, z2);
-        modular_add(z2, x1, z1);
-        modular_subtract(x1, x1, z1);
-        modular_multiply(t1, t1, x1);
-        modular_multiply(x2, x2, z2);
-        modular_square(z2, z2);
-        modular_square(x1, x1);
-        modular_subtract(t2, z2, x1);
-        modular_multiply_single(z1, t2, A24);
-        modular_add(z1, z1, x1);
-        modular_multiply(z1, z1, t2);
-        modular_multiply(x1, x1, z2);
-        modular_subtract(z2, t1, x2);
-        modular_square(z2, z2);
-        modular_multiply(z2, z2, u);
-        modular_add(x2, x2, t1);
-        modular_square(x2, x2);
+        Curve25519::modular_add(t1, x2, z2);
+        Curve25519::modular_subtract(x2, x2, z2);
+        Curve25519::modular_add(z2, x1, z1);
+        Curve25519::modular_subtract(x1, x1, z1);
+        Curve25519::modular_multiply(t1, t1, x1);
+        Curve25519::modular_multiply(x2, x2, z2);
+        Curve25519::modular_square(z2, z2);
+        Curve25519::modular_square(x1, x1);
+        Curve25519::modular_subtract(t2, z2, x1);
+        Curve25519::modular_multiply_single(z1, t2, A24);
+        Curve25519::modular_add(z1, z1, x1);
+        Curve25519::modular_multiply(z1, z1, t2);
+        Curve25519::modular_multiply(x1, x1, z2);
+        Curve25519::modular_subtract(z2, t1, x2);
+        Curve25519::modular_square(z2, z2);
+        Curve25519::modular_multiply(z2, z2, u);
+        Curve25519::modular_add(x2, x2, t1);
+        Curve25519::modular_square(x2, x2);
     }
 
     conditional_swap(x1, x2, swap);
     conditional_swap(z1, z2, swap);
 
     // Retrieve affine representation
-    modular_multiply_inverse(u, z1);
-    modular_multiply(u, u, x1);
+    Curve25519::modular_multiply_inverse(u, z1);
+    Curve25519::modular_multiply(u, u, x1);
 
     // Encode state for export
-    return export_state(u);
+    auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
+    Curve25519::export_state(u, buffer.data());
+
+    return buffer;
 }
 
 ErrorOr<ByteBuffer> X25519::derive_premaster_key(ReadonlyBytes shared_point)