diff options
Diffstat (limited to 'crypto/src/math/ec/rfc8032/Ed25519.cs')
| -rw-r--r-- | crypto/src/math/ec/rfc8032/Ed25519.cs | 265 |
1 files changed, 263 insertions, 2 deletions
diff --git a/crypto/src/math/ec/rfc8032/Ed25519.cs b/crypto/src/math/ec/rfc8032/Ed25519.cs index d88914c90..128ec4244 100644 --- a/crypto/src/math/ec/rfc8032/Ed25519.cs +++ b/crypto/src/math/ec/rfc8032/Ed25519.cs @@ -92,12 +92,12 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 private static PointPrecomp[] PrecompBaseWnaf = null; private static int[] PrecompBaseComb = null; - private ref struct PointAccum + private struct PointAccum { internal int[] x, y, z, u, v; } - private ref struct PointAffine + private struct PointAffine { internal int[] x, y; } @@ -238,6 +238,17 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 return n; } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static uint Decode32(ReadOnlySpan<byte> bs) + { + uint n = bs[0]; + n |= (uint)bs[1] << 8; + n |= (uint)bs[2] << 16; + n |= (uint)bs[3] << 24; + return n; + } +#endif + private static void Decode32(byte[] bs, int bsOff, uint[] n, int nOff, int nLen) { for (int i = 0; i < nLen; ++i) @@ -246,6 +257,16 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 } } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static void Decode32(ReadOnlySpan<byte> bs, Span<uint> n) + { + for (int i = 0; i < n.Length; ++i) + { + n[i] = Decode32(bs[(i * 4)..]); + } + } +#endif + private static bool DecodePointVar(byte[] p, int pOff, bool negate, ref PointAffine r) { byte[] py = Copy(p, pOff, PointBytes); @@ -285,6 +306,13 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 Decode32(k, kOff, n, 0, ScalarUints); } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static void DecodeScalar(ReadOnlySpan<byte> k, Span<uint> n) + { + Decode32(k, n[..ScalarUints]); + } +#endif + private static void Dom2(IDigest d, byte phflag, byte[] ctx) { if (ctx != null) @@ -323,6 +351,9 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 private static int EncodePoint(ref PointAccum p, byte[] r, int rOff) { +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + return EncodePoint(ref p, r.AsSpan(rOff)); +#else int[] x = F.Create(); int[] y = F.Create(); @@ -338,13 +369,48 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 r[rOff + PointBytes - 1] |= (byte)((x[0] & 1) << 7); return result; +#endif + } + +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static int EncodePoint(ref PointAccum p, Span<byte> r) + { + int[] x = F.Create(); + int[] y = F.Create(); + + F.Inv(p.z, y); + F.Mul(p.x, y, x); + F.Mul(p.y, y, y); + F.Normalize(x); + F.Normalize(y); + + int result = CheckPoint(x, y); + + F.Encode(y, r); + r[PointBytes - 1] |= (byte)((x[0] & 1) << 7); + + return result; } +#endif public static void GeneratePrivateKey(SecureRandom random, byte[] k) { + if (k.Length != SecretKeySize) + throw new ArgumentException(nameof(k)); + random.NextBytes(k); } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + public static void GeneratePrivateKey(SecureRandom random, Span<byte> k) + { + if (k.Length != SecretKeySize) + throw new ArgumentException(nameof(k)); + + random.NextBytes(k); + } +#endif + public static void GeneratePublicKey(byte[] sk, int skOff, byte[] pk, int pkOff) { IDigest d = CreateDigest(); @@ -359,7 +425,27 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 ScalarMultBaseEncoded(s, pk, pkOff); } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + public static void GeneratePublicKey(ReadOnlySpan<byte> sk, Span<byte> pk) + { + IDigest d = CreateDigest(); + Span<byte> h = stackalloc byte[d.GetDigestSize()]; + + d.BlockUpdate(sk[..SecretKeySize]); + d.DoFinal(h); + + Span<byte> s = stackalloc byte[ScalarBytes]; + PruneScalar(h, s); + + ScalarMultBaseEncoded(s, pk); + } +#endif + +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static uint GetWindow4(ReadOnlySpan<uint> x, int n) +#else private static uint GetWindow4(uint[] x, int n) +#endif { int w = (int)((uint)n >> 3), b = (n & 7) << 2; return (x[w] >> b) & 15U; @@ -818,6 +904,32 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 } } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static void PointLookupZ(ReadOnlySpan<uint> x, int n, ReadOnlySpan<int> table, ref PointPrecompZ r) + { + // TODO This method is currently hard-coded to 4-bit windows and 8 precomputed points + + uint w = GetWindow4(x, n); + + int sign = (int)(w >> (4 - 1)) ^ 1; + int abs = ((int)w ^ -sign) & 7; + + Debug.Assert(sign == 0 || sign == 1); + Debug.Assert(0 <= abs && abs < 8); + + for (int i = 0; i < 8; ++i) + { + int cond = ((i ^ abs) - 1) >> 31; + F.CMov(cond, table, r.ymx_h); table = table[F.Size..]; + F.CMov(cond, table, r.ypx_h); table = table[F.Size..]; + F.CMov(cond, table, r.xyd); table = table[F.Size..]; + F.CMov(cond, table, r.z); table = table[F.Size..]; + } + + F.CSwap(sign, r.ymx_h, r.ypx_h); + F.CNegate(sign, r.xyd); + } +#else private static void PointLookupZ(uint[] x, int n, int[] table, ref PointPrecompZ r) { // TODO This method is currently hard-coded to 4-bit windows and 8 precomputed points @@ -842,6 +954,7 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 F.CSwap(sign, r.ymx_h, r.ypx_h); F.CNegate(sign, r.xyd); } +#endif private static void PointPrecompute(ref PointAffine p, PointExtended[] points, int count, ref PointTemp t) { @@ -1070,6 +1183,17 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 r[ScalarBytes - 1] |= 0x40; } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static void PruneScalar(ReadOnlySpan<byte> n, Span<byte> r) + { + n[..ScalarBytes].CopyTo(r); + + r[0] &= 0xF8; + r[ScalarBytes - 1] &= 0x7F; + r[ScalarBytes - 1] |= 0x40; + } +#endif + private static byte[] ReduceScalar(byte[] n) { long x00 = Decode32(n, 0) & M32L; // x00:32/-- @@ -1208,6 +1332,9 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 private static void ScalarMult(byte[] k, ref PointAffine p, ref PointAccum r) { +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + ScalarMult(k.AsSpan(), ref p, ref r); +#else uint[] n = new uint[ScalarUints]; DecodeScalar(k, 0, n); @@ -1237,10 +1364,49 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 PointDouble(ref r); } } +#endif } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static void ScalarMult(ReadOnlySpan<byte> k, ref PointAffine p, ref PointAccum r) + { + Span<uint> n = stackalloc uint[ScalarUints]; + DecodeScalar(k, n); + + // Recode the scalar into signed-digit form + { + uint c1 = Nat.CAdd(ScalarUints, ~(int)n[0] & 1, n, L, n); Debug.Assert(c1 == 0U); + uint c2 = Nat.ShiftDownBit(ScalarUints, n, 1U); Debug.Assert(c2 == (1U << 31)); + } + + Init(out PointPrecompZ q); + Init(out PointTemp t); + int[] table = PointPrecomputeZ(ref p, 8, ref t); + + PointSetNeutral(ref r); + + int w = 63; + for (;;) + { + PointLookupZ(n, w, table, ref q); + PointAdd(ref q, ref r, ref t); + + if (--w < 0) + break; + + for (int i = 0; i < 4; ++i) + { + PointDouble(ref r); + } + } + } +#endif + private static void ScalarMultBase(byte[] k, ref PointAccum r) { +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + ScalarMultBase(k.AsSpan(), ref r); +#else // Equivalent (but much slower) //PointAffine p; Init(out p); //F.Copy(B_x, 0, p.x, 0); @@ -1302,8 +1468,76 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 F.CNegate(resultSign, r.x); F.CNegate(resultSign, r.u); +#endif } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static void ScalarMultBase(ReadOnlySpan<byte> k, ref PointAccum r) + { + // Equivalent (but much slower) + //Init(out PointAffine p); + //F.Copy(B_x, 0, p.x, 0); + //F.Copy(B_y, 0, p.y, 0); + //ScalarMult(k, ref p, ref r); + + Precompute(); + + Span<uint> n = stackalloc uint[ScalarUints]; + DecodeScalar(k, n); + + // Recode the scalar into signed-digit form, then group comb bits in each block + { + uint c1 = Nat.CAdd(ScalarUints, ~(int)n[0] & 1, n, L, n); Debug.Assert(c1 == 0U); + uint c2 = Nat.ShiftDownBit(ScalarUints, n, 1U); Debug.Assert(c2 == (1U << 31)); + + /* + * Because we are using 4 teeth and 8 spacing, each limb of n corresponds to one of the 8 blocks. + * Therefore we can efficiently group the bits for each comb position using a (double) shuffle. + */ + for (int i = 0; i < ScalarUints; ++i) + { + n[i] = Interleave.Shuffle2(n[i]); + } + } + + Init(out PointPrecomp p); + Init(out PointTemp t); + + PointSetNeutral(ref r); + int resultSign = 0; + + int cOff = (PrecompSpacing - 1) * PrecompTeeth; + for (;;) + { + for (int b = 0; b < PrecompBlocks; ++b) + { + uint w = n[b] >> cOff; + int sign = (int)(w >> (PrecompTeeth - 1)) & 1; + int abs = ((int)w ^ -sign) & PrecompMask; + + Debug.Assert(sign == 0 || sign == 1); + Debug.Assert(0 <= abs && abs < PrecompPoints); + + PointLookup(b, abs, ref p); + + F.CNegate(resultSign ^ sign, r.x); + F.CNegate(resultSign ^ sign, r.u); + resultSign = sign; + + PointAdd(ref p, ref r, ref t); + } + + if ((cOff -= PrecompTeeth) < 0) + break; + + PointDouble(ref r); + } + + F.CNegate(resultSign, r.x); + F.CNegate(resultSign, r.u); + } +#endif + private static void ScalarMultBaseEncoded(byte[] k, byte[] r, int rOff) { PointAccum p; Init(out p); @@ -1312,6 +1546,16 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 throw new InvalidOperationException(); } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + private static void ScalarMultBaseEncoded(ReadOnlySpan<byte> k, Span<byte> r) + { + Init(out PointAccum p); + ScalarMultBase(k, ref p); + if (0 == EncodePoint(ref p, r)) + throw new InvalidOperationException(); + } +#endif + internal static void ScalarMultBaseYZ(byte[] k, int kOff, int[] y, int[] z) { byte[] n = new byte[ScalarBytes]; @@ -1327,6 +1571,23 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032 F.Copy(p.z, 0, z, 0); } +#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER + internal static void ScalarMultBaseYZ(ReadOnlySpan<byte> k, Span<int> y, Span<int> z) + { + Span<byte> n = stackalloc byte[ScalarBytes]; + PruneScalar(k, n); + + Init(out PointAccum p); + ScalarMultBase(n, ref p); + + if (0 == CheckPoint(p.x, p.y, p.z)) + throw new InvalidOperationException(); + + F.Copy(p.y, y); + F.Copy(p.z, z); + } +#endif + private static void ScalarMultOrderVar(ref PointAffine p, ref PointAccum r) { sbyte[] ws_p = GetWnafVar(L, WnafWidth); |