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key encapulation works
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@jlmucb
jlmucb committed Apr 28, 2024
1 parent 4c560ef commit c17cb28
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Showing 2 changed files with 70 additions and 17 deletions.
73 changes: 61 additions & 12 deletions v2/kyber/kyber.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1553,18 +1553,21 @@ bool kyber_decrypt(int g, kyber_parameters& p, int dk_len, byte* dk,
// full
bool kyber_kem_keygen(int g, kyber_parameters& p, int* kem_ek_len, byte* kem_ek,
int* kem_dk_len, byte* kem_dk) {

byte z[32];
int n_b = crypto_get_random_bytes(32, z);
if (n_b != 32) {
printf("kyber_kem_keygen crypto_get_random_bytes returne wrong nuber of bytes\n");
printf("kyber_kem_keygen: crypto_get_random_bytes returne wrong nuber of bytes\n");
return false;
}

int dk_PKE_len = 384 * p.k_;
byte dk_PKE[dk_PKE_len];
if (! kyber_keygen(g, p, kem_ek_len, kem_ek, &dk_PKE_len, dk_PKE)) {
if (!kyber_keygen(g, p, kem_ek_len, kem_ek, &dk_PKE_len, dk_PKE)) {
printf("kyber_kem_keygen: kyber_keygen failed\n");
return false;
}
int ek_PKE_len = 384 * p.k_ + 32;

// kem_dk = dk_PKE || ek || H(ek) || z
int len = 0;
Expand All @@ -1580,13 +1583,32 @@ bool kyber_kem_keygen(int g, kyber_parameters& p, int* kem_ek_len, byte* kem_ek,
h.add_to_hash(*kem_ek_len, kem_ek);
h.finalize();
h.get_digest(32, &kem_dk[len]);

byte* ph = &kem_dk[len];
len += 32;

byte* pz = &kem_dk[len];
memcpy(&kem_dk[len], z, 32);
len += 32;

if (*kem_dk_len < len) {
printf("kyber_kem_keygen: dk_kem buffer too small\n");
return false;
}
*kem_dk_len = len;
#if 1
printf("ek (%d) :\n", ek_PKE_len);
print_bytes(ek_PKE_len, kem_ek);
printf("\n");
printf("dk_PKE (%d) :\n", dk_PKE_len);
print_bytes(dk_PKE_len, dk_PKE);
printf("\n");
printf("h (%d) :\n", 32);
print_bytes(32, ph);
printf("\n");
printf("z (%d) :\n", 32);
print_bytes(32, pz);
printf("\n");
#endif
return true;
}

Expand All @@ -1605,6 +1627,11 @@ bool kyber_kem_encaps(int g, kyber_parameters& p, int kem_ek_len, byte* kem_ek,
return false;
}

#ifdef LONG_DEBUG
printf("m: ");
print_bytes(32, m);
#endif

byte ek_hash[32];
memset(ek_hash, 0, 32);

Expand All @@ -1623,7 +1650,7 @@ bool kyber_kem_encaps(int g, kyber_parameters& p, int kem_ek_len, byte* kem_ek,

// (K, r) := G(H(pk), m)
byte K_r[64];
if (!G(64, G_input, 64, K_r)) {
if (!G(64, G_input, 512, K_r)) {
printf("kyber_kem_encaps: Can't compute G\n");
return false;
}
Expand All @@ -1644,17 +1671,17 @@ bool kyber_kem_encaps(int g, kyber_parameters& p, int kem_ek_len, byte* kem_ek,
printf("kyber_kem_encaps: k_len too small\n");
return false;
}

memcpy(k, pK, 32);

return true;
}

// Kem.Decapsulate
// dk := dk[0:384k] = dk[0:48] (bytes)
// ek := dk[384k:768k + 32] = dk[48:128] (bytes)
// h := dk[768k + 32: 768k+64 = dk[128:160] (bytes)]
// z := dk[768k+64: 768k+96 = dk[160:192] (bytes)
// m' := Kyber.Dec(dk, c)
// dk_PKE := dk[0:384k]
// ek_PKE := dk[384k:768k + 32]
// h := dk[768k + 32: 768k+64]
// z := dk[768k+64: 768k+96]
// m' := Kyber.Dec(dk_PKE, c)
// (K', r') := G(m'|| h)
// K-bar = J(z||c, 32)
// c' := Kyber.Enc(m',r')
Expand All @@ -1672,27 +1699,49 @@ bool kyber_kem_decaps(int g, kyber_parameters& p, int kem_dk_len, byte* kem_dk,
byte* h = &kem_dk[ek_PKE_len + dk_PKE_len];
byte* z = &kem_dk[ek_PKE_len + dk_PKE_len + 32];

#ifdef LONG_DEBUG
printf("\nkey_decaps\n");
printf("ek_PKE(%d):\n", ek_PKE_len);
print_bytes(ek_PKE_len, ek_PKE);
printf("dk_PKE(%d):\n", dk_PKE_len);
print_bytes(dk_PKE_len, dk_PKE);
printf("h (%d): ", 32);
print_bytes(32, h);
printf("z (%d): ", 32);
print_bytes(32, z);
#endif

int m_prime_len = 32;
byte m_prime[m_prime_len];
if (!kyber_decrypt(g, p, dk_PKE_len, dk_PKE, c_len, c, &m_prime_len, m_prime)) {
printf("kyber_kem_decaps: PKE decrypt failed\n");
return false;
}

#ifdef LONG_DEBUG
printf("recovered m: ");
print_bytes(32, m_prime);
#endif

byte G_to_hash[64];
memcpy(G_to_hash, m_prime, 32);
memcpy(&G_to_hash[32], h, 32);

// (K_prime, r_prime) := G(H(pk), m)
byte K_r_prime[64];
if (!G(64, G_to_hash, 64, K_r_prime)) {
if (!G(64, G_to_hash, 512, K_r_prime)) {
printf("kyber_kem_decaps: G failed\n");
return false;
}
byte* pK_prime = K_r_prime;
byte* pr_prime = &K_r_prime[32];
byte K_bar[32];

#ifdef LONG_DEBUG
printf("K_prime: ");
print_bytes(32, pK_prime);
#endif

// J (shake-256)
sha3 h_o;
if (!h_o.init(512, 256)) {
Expand All @@ -1715,7 +1764,7 @@ bool kyber_kem_decaps(int g, kyber_parameters& p, int kem_dk_len, byte* kem_dk,
printf("kyber_kem_decaps: c != c_prime\n");
return false;
}
memcpy(k, K_bar, 32);
memcpy(k, pK_prime, 32);
*k_len = 32;
return true;
}
Expand Down
14 changes: 9 additions & 5 deletions v2/kyber/test_kyber.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -93,12 +93,17 @@ bool test_kyber1() {
if (FLAGS_print_all) {
printf("recovered m: ");
print_bytes(recovered_m_len, recovered_m);
printf("\n\nkyber complete\n\n");
}
if (memcmp(m, recovered_m, m_len) != 0) {
printf("message and recovered message dont match\n");
return false;
}

if (FLAGS_print_all) {
printf("\n\nkem\n\n");
}

int kem_ek_len = 384 * p.k_ + 32;
byte kem_ek[kem_ek_len];
memset(kem_ek, 0, kem_ek_len);
Expand All @@ -120,7 +125,7 @@ bool test_kyber1() {
memset(kem_k, 0, kem_k_len);

if (FLAGS_print_all) {
printf("\n\nken_keygen\n\n");
printf("\n\nkem_keygen\n\n");
printf("kem_ek (%d):\n", kem_ek_len);
print_bytes(kem_ek_len, kem_ek);
printf("\n");
Expand All @@ -136,9 +141,9 @@ bool test_kyber1() {
}

if (FLAGS_print_all) {
printf("\n\nken_encaps\n\n");
printf("k (%d):\n", kem_k_len);
print_bytes(kem_ek_len, kem_ek);
printf("\n\nkem_encaps\n\n");
printf("k (%d): ", kem_k_len);
print_bytes(kem_k_len, kem_k);
printf("\n");
printf("c (%d):\n", kem_c_len);
print_bytes(kem_c_len, kem_c);
Expand All @@ -162,7 +167,6 @@ bool test_kyber1() {
printf("recovered key (%d): ", recovered_k_len);
print_bytes(recovered_k_len, recovered_k);
}
return true;

if (memcmp(kem_k, recovered_k, recovered_k_len) != 0) {
printf("Generated and encapsulated keys don't match\n");
Expand Down

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