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using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Pqc.Crypto.Sike
{
internal sealed class SikeEngine
{
internal Internal param;
internal Isogeny isogeny;
internal Fpx fpx;
private Sidh sidh;
private SidhCompressed sidhCompressed;
private bool isCompressed;
internal uint GetDefaultSessionKeySize()
{
return param.MSG_BYTES * 8;
}
internal int GetCipherTextSize()
{
return param.CRYPTO_CIPHERTEXTBYTES;
}
internal uint GetPrivateKeySize()
{
return param.CRYPTO_SECRETKEYBYTES;
}
internal uint GetPublicKeySize()
{
return param.CRYPTO_PUBLICKEYBYTES;
}
internal SikeEngine(int ver, bool isCompressed, SecureRandom random)
{
//this.random = random;
this.isCompressed = isCompressed;
//todo switch for different parameters
switch(ver)
{
case 434:
param = new P434(isCompressed);
break;
case 503:
param = new P503(isCompressed);
break;
case 610:
param = new P610(isCompressed);
break;
case 751:
param = new P751(isCompressed);
break;
default:
break;
}
fpx = new Fpx(this);
isogeny = new Isogeny(this);
if(isCompressed)
{
sidhCompressed = new SidhCompressed(this);
}
sidh = new Sidh(this);
}
// SIKE's key generation
// Outputs: secret key sk (CRYPTO_SECRETKEYBYTES = MSG_BYTES + SECRETKEY_B_BYTES + CRYPTO_PUBLICKEYBYTES bytes)
// public key pk (CRYPTO_PUBLICKEYBYTES bytes)
internal int crypto_kem_keypair(byte[] pk, byte[] sk, SecureRandom random)
{
random.NextBytes(sk, 0, (int)param.MSG_BYTES);
if (isCompressed)
{
// Generation of Alice's secret key
// Outputs random value in [0, 2^eA - 1]
random.NextBytes(sk, (int)param.MSG_BYTES, (int)param.SECRETKEY_A_BYTES);
sk[param.MSG_BYTES] &= 0xFE; // Make private scalar even
sk[param.MSG_BYTES + param.SECRETKEY_A_BYTES - 1] &= (byte)param.MASK_ALICE; // Masking last
sidhCompressed.EphemeralKeyGeneration_A_extended(sk, pk);
// Append public key pk to secret key sk
System.Array.Copy(pk, 0, sk, param.MSG_BYTES + param.SECRETKEY_A_BYTES, param.CRYPTO_PUBLICKEYBYTES);
}
else
{
// Generation of Bob's secret key
// Outputs random value in [0, 2^Floor(Log(2, oB)) - 1]
// todo/org: SIDH.random_mod_order_B(sk, random);
random.NextBytes(sk, (int)param.MSG_BYTES, (int)param.SECRETKEY_B_BYTES);
sk[param.MSG_BYTES + param.SECRETKEY_B_BYTES - 1] &= (byte)param.MASK_BOB;
sidh.EphemeralKeyGeneration_B(sk, pk);
// Append public key pk to secret key sk
System.Array.Copy(pk, 0, sk, param.MSG_BYTES + param.SECRETKEY_B_BYTES, param.CRYPTO_PUBLICKEYBYTES);
}
return 0;
}
// SIKE's encapsulation
// Input: public key pk (CRYPTO_PUBLICKEYBYTES bytes)
// Outputs: shared secret ss (CRYPTO_BYTES bytes)
// ciphertext message ct (CRYPTO_CIPHERTEXTBYTES = CRYPTO_PUBLICKEYBYTES + MSG_BYTES bytes)
internal int crypto_kem_enc(byte[] ct, byte[] ss, byte[] pk, SecureRandom random)
{
if(isCompressed)
{
byte[] ephemeralsk = new byte[param.SECRETKEY_B_BYTES];
byte[] jinvariant = new byte[param.FP2_ENCODED_BYTES];
byte[] h = new byte[param.MSG_BYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
// Generate ephemeralsk <- G(m||pk) mod oB
random.NextBytes(temp, 0, (int)param.MSG_BYTES);
System.Array.Copy(pk, 0, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk, 0, (int) param.SECRETKEY_B_BYTES);
sidhCompressed.FormatPrivKey_B(ephemeralsk);
// System.out.println("ephemeralsk: " + Hex.toHexstring(ephemeralsk));
// Encrypt
sidhCompressed.EphemeralKeyGeneration_B_extended(ephemeralsk, ct, 1);
// System.out.println("ct: " + Hex.toHexstring(ct));
// System.out.println("pk: " + Hex.toHexstring(pk));
sidhCompressed.EphemeralSecretAgreement_B(ephemeralsk, pk, jinvariant);
// System.out.println("jinv: " + Hex.toHexstring(jinvariant));
digest.BlockUpdate(jinvariant, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h, 0, (int) param.MSG_BYTES);
// System.out.println("h: " + Hex.toHexstring(h));
// System.out.println("temp: " + Hex.toHexstring(temp));
for (int i = 0; i < param.MSG_BYTES; i++)
{
ct[i + param.PARTIALLY_COMPRESSED_CHUNK_CT] = (byte) (temp[i] ^ h[i]);
}
// Generate shared secret ss <- H(m||ct)
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
else
{
byte[] ephemeralsk = new byte[param.SECRETKEY_A_BYTES];
byte[] jinvariant = new byte[param.FP2_ENCODED_BYTES];
byte[] h = new byte[param.MSG_BYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
// Generate ephemeralsk <- G(m||pk) mod oA
random.NextBytes(temp, 0, (int)param.MSG_BYTES);
System.Array.Copy(pk, 0, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk, 0, (int) param.SECRETKEY_A_BYTES);
ephemeralsk[param.SECRETKEY_A_BYTES - 1] &= (byte) param.MASK_ALICE;
// Encrypt
sidh.EphemeralKeyGeneration_A(ephemeralsk, ct);
sidh.EphemeralSecretAgreement_A(ephemeralsk, pk, jinvariant);
digest.BlockUpdate(jinvariant, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h, 0, (int) param.MSG_BYTES);
for (int i = 0; i < param.MSG_BYTES; i++)
{
ct[i + param.CRYPTO_PUBLICKEYBYTES] = (byte) (temp[i] ^ h[i]);
}
// Generate shared secret ss <- H(m||ct)
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
}
// SIKE's decapsulation
// Input: secret key sk (CRYPTO_SECRETKEYBYTES = MSG_BYTES + SECRETKEY_B_BYTES + CRYPTO_PUBLICKEYBYTES bytes)
// ciphertext message ct (CRYPTO_CIPHERTEXTBYTES = CRYPTO_PUBLICKEYBYTES + MSG_BYTES bytes)
// Outputs: shared secret ss (CRYPTO_BYTES bytes)
internal int crypto_kem_dec(byte[] ss, byte[] ct, byte[] sk)
{
if (isCompressed)
{
byte[] ephemeralsk_ = new byte[param.SECRETKEY_B_BYTES];
byte[] jinvariant_ = new byte[param.FP2_ENCODED_BYTES + 2*param.FP2_ENCODED_BYTES + param.SECRETKEY_A_BYTES],
h_ = new byte[param.MSG_BYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
byte[] tphiBKA_t = jinvariant_;//jinvariant_[param.FP2_ENCODED_BYTES];
// Decrypt
sidhCompressed.EphemeralSecretAgreement_A_extended(sk, param.MSG_BYTES, ct, jinvariant_, 1);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(jinvariant_, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h_, 0, (int) param.MSG_BYTES);
// System.out.println("h_: " + Hex.toHexstring(h_));
for (int i = 0; i < param.MSG_BYTES; i++)
{
temp[i] = (byte) (ct[i + param.PARTIALLY_COMPRESSED_CHUNK_CT] ^ h_[i]);
}
// Generate ephemeralsk_ <- G(m||pk) mod oB
System.Array.Copy(sk, param.MSG_BYTES + param.SECRETKEY_A_BYTES, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk_, 0, (int) param.SECRETKEY_B_BYTES);
sidhCompressed.FormatPrivKey_B(ephemeralsk_);
// Generate shared secret ss <- H(m||ct), or output ss <- H(s||ct) in case of ct verification failure
// No need to recompress, just check if x(phi(P) + t*phi(Q)) == x((a0 + t*a1)*R1 + (b0 + t*b1)*R2)
byte selector = sidhCompressed.validate_ciphertext(ephemeralsk_, ct, sk, param.MSG_BYTES + param.SECRETKEY_A_BYTES + param.CRYPTO_PUBLICKEYBYTES, tphiBKA_t, param.FP2_ENCODED_BYTES);
// If ct validation passes (selector = 0) then do ss = H(m||ct), otherwise (selector = -1) load s to do ss = H(s||ct)
fpx.ct_cmov(temp, sk, param.MSG_BYTES, selector);
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
else
{
byte[] ephemeralsk_ = new byte[param.SECRETKEY_A_BYTES];
byte[] jinvariant_ = new byte[param.FP2_ENCODED_BYTES];
byte[] h_ = new byte[param.MSG_BYTES];
byte[] c0_ = new byte[param.CRYPTO_PUBLICKEYBYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
// Decrypt
// int EphemeralSecretAgreement_B(PrivateKeyB, PublicKeyA, SharedSecretB)
sidh.EphemeralSecretAgreement_B(sk, ct, jinvariant_);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(jinvariant_, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h_, 0, (int) param.MSG_BYTES);
for (int i = 0; i < param.MSG_BYTES; i++)
{
temp[i] = (byte) (ct[i + param.CRYPTO_PUBLICKEYBYTES] ^ h_[i]);
}
// Generate ephemeralsk_ <- G(m||pk) mod oA
System.Array.Copy(sk, param.MSG_BYTES + param.SECRETKEY_B_BYTES, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk_, 0, (int) param.SECRETKEY_A_BYTES);
ephemeralsk_[param.SECRETKEY_A_BYTES - 1] &= (byte) param.MASK_ALICE;
// Generate shared secret ss <- H(m||ct), or output ss <- H(s||ct) in case of ct verification failure
sidh.EphemeralKeyGeneration_A(ephemeralsk_, c0_);
// If selector = 0 then do ss = H(m||ct), else if selector = -1 load s to do ss = H(s||ct)
byte selector = fpx.ct_compare(c0_, ct, param.CRYPTO_PUBLICKEYBYTES);
fpx.ct_cmov(temp, sk, param.MSG_BYTES, selector);
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
}
}
}
|
