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Commit a5de7f32 authored by npzacs's avatar npzacs
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crypto: parametrize ECDSA curve, hash algorithm and key size

parent b47a66bd
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Showing with 68 additions and 33 deletions
src/libaacs/crypto.c
View file @ a5de7f32
......@@ -249,15 +249,32 @@ void crypto_aes_cmac_16(const unsigned char *data, const unsigned char *aes_key,
* build S-expressions
*/
static const char *_aacs1_curve(void)
{
return
"(p #00"AACS_EC_p"#)"
"(a #00"AACS_EC_a"#)"
"(b #00"AACS_EC_b"#)"
"(g #04"
AACS_EC_G_x
AACS_EC_G_y
"#)"
"(n #00"AACS_EC_n"#)";
}
static gcry_error_t _aacs_sexp_key(gcry_sexp_t *p_sexp_key,
const uint8_t *q_x, const uint8_t *q_y,
const uint8_t *priv_key)
const uint8_t *priv_key,
const char *curve,
size_t key_len)
{
gcry_mpi_t mpi_d = NULL;
unsigned char Q[41];
char str_Q[sizeof(Q) * 2 + 1];
gcry_error_t err;
BD_ASSERT (key_len == 20);
/* Assign MPI values for ECDSA parameters Q and d.
* Values are:
* Q.x = c[12]..c[31]
......@@ -267,17 +284,17 @@ static gcry_error_t _aacs_sexp_key(gcry_sexp_t *p_sexp_key,
* Note: The MPI values for Q are in the form "<format>||Q.x||Q.y".
*/
memcpy(&Q[0], "\x04", 1); // format
memcpy(&Q[1], q_x, 20); // Q.x
memcpy(&Q[21], q_y, 20); // Q.y
memcpy(&Q[1], q_x, key_len); // Q.x
memcpy(&Q[1 + key_len], q_y, key_len); // Q.y
if (priv_key) {
gcry_mpi_scan(&mpi_d, GCRYMPI_FMT_USG, priv_key, 20, NULL);
gcry_mpi_scan(&mpi_d, GCRYMPI_FMT_USG, priv_key, key_len, NULL);
}
/* Show the values of the MPIs Q.x, Q.y, and d when debugging */
if (GCRYPT_DEBUG) {
gcry_mpi_t mpi_Q_x, mpi_Q_y;
gcry_mpi_scan(&mpi_Q_x, GCRYMPI_FMT_USG, q_x, 20, NULL);
gcry_mpi_scan(&mpi_Q_y, GCRYMPI_FMT_USG, q_y, 20, NULL);
gcry_mpi_scan(&mpi_Q_x, GCRYMPI_FMT_USG, q_x, key_len, NULL);
gcry_mpi_scan(&mpi_Q_y, GCRYMPI_FMT_USG, q_y, key_len, NULL);
gcry_mpi_dump(mpi_Q_x);
printf("\n");
gcry_mpi_dump(mpi_Q_y);
......@@ -303,22 +320,16 @@ static gcry_error_t _aacs_sexp_key(gcry_sexp_t *p_sexp_key,
/* Points are currently only supported in standard format, so get a
* hexstring out of Q.
*/
hex_array_to_hexstring(str_Q, Q, sizeof(Q));
hex_array_to_hexstring(str_Q, Q, 1 + 2*key_len);
char *strfmt = str_printf(
"(%s"
"(ecdsa"
"(p #00"AACS_EC_p"#)"
"(a #00"AACS_EC_a"#)"
"(b #00"AACS_EC_b"#)"
"(g #04"
AACS_EC_G_x
AACS_EC_G_y
"#)"
"(n #00"AACS_EC_n"#)"
"%s"
"(q #%s#)"
"%s))",
mpi_d ? "private-key" : "public-key",
curve,
str_Q,
mpi_d ? "(d %m)" : ""
);
......@@ -348,15 +359,26 @@ error:
return err;
}
static gcry_error_t _aacs_sexp_sha1(gcry_sexp_t *p_sexp_data,
const uint8_t *block, uint32_t len)
static gcry_error_t _aacs_sexp_hash(gcry_sexp_t *p_sexp_data,
const uint8_t *block, uint32_t len,
enum gcry_md_algos hash_type)
{
gcry_mpi_t mpi_md = NULL;
uint8_t md[20];
gcry_error_t err;
size_t hash_size;
gcry_md_hash_buffer(GCRY_MD_SHA1, md, block, len);
gcry_mpi_scan(&mpi_md, GCRYMPI_FMT_USG, md, sizeof(md), NULL);
switch (hash_type) {
case GCRY_MD_SHA1:
hash_size = 20;
break;
default:
BD_ASSERT_UNREACHABLE ("unsupported hash algorithm");
return GPG_ERR_UNKNOWN_ALGORITHM;
}
gcry_md_hash_buffer(hash_type, md, block, len);
gcry_mpi_scan(&mpi_md, GCRYMPI_FMT_USG, md, hash_size, NULL);
/* Dump information about the md MPI when debugging */
if (GCRYPT_DEBUG) {
......@@ -396,14 +418,15 @@ static gcry_error_t _aacs_sexp_sha1(gcry_sexp_t *p_sexp_data,
}
static gcry_error_t _aacs_sexp_signature(gcry_sexp_t *p_sexp_sign,
const uint8_t *signature)
const uint8_t *signature,
size_t key_len)
{
gcry_mpi_t mpi_r = NULL;
gcry_mpi_t mpi_s = NULL;
gcry_error_t err;
gcry_mpi_scan(&mpi_r, GCRYMPI_FMT_USG, signature, 20, NULL);
gcry_mpi_scan(&mpi_s, GCRYMPI_FMT_USG, signature + 20, 20, NULL);
gcry_mpi_scan(&mpi_r, GCRYMPI_FMT_USG, signature, key_len, NULL);
gcry_mpi_scan(&mpi_s, GCRYMPI_FMT_USG, signature + key_len, key_len, NULL);
/* Dump information about the md MPI when debugging */
if (GCRYPT_DEBUG) {
......@@ -447,7 +470,7 @@ void crypto_aacs_sign(const uint8_t *cert, const uint8_t *priv_key, uint8_t *sig
gcry_error_t err;
GCRY_VERIFY("_aacs_sexp_key",
_aacs_sexp_key(&sexp_key, cert + 12, cert + 32, priv_key));
_aacs_sexp_key(&sexp_key, cert + 12, cert + 32, priv_key, _aacs1_curve(), 20));
/* Calculate the sha1 hash from the nonce and host key point and covert
* the hash into an MPI.
......@@ -455,8 +478,8 @@ void crypto_aacs_sign(const uint8_t *cert, const uint8_t *priv_key, uint8_t *sig
memcpy(&block[0], nonce, 20);
memcpy(&block[20], point, 40);
GCRY_VERIFY("_aacs_sexp_sha1",
_aacs_sexp_sha1(&sexp_data, block, sizeof(block)));
GCRY_VERIFY("_aacs_sexp_hash",
_aacs_sexp_hash(&sexp_data, block, sizeof(block), GCRY_MD_SHA1));
/* Sign the hash with the ECDSA key. The resulting s-expression should be
* in the form:
......@@ -501,7 +524,7 @@ void crypto_aacs_sign(const uint8_t *cert, const uint8_t *priv_key, uint8_t *sig
gcry_mpi_release(mpi_s);
}
static int _aacs_verify(const uint8_t *signature,
static int _aacs_verify(const uint8_t *signature, enum gcry_md_algos hash_type,
const uint8_t *q_x, const uint8_t *q_y,
const uint8_t *data, uint32_t len)
{
......@@ -509,15 +532,27 @@ static int _aacs_verify(const uint8_t *signature,
gcry_sexp_t sexp_sig = NULL;
gcry_sexp_t sexp_data = NULL;
gcry_error_t err;
const char *curve;
size_t key_len;
switch (hash_type) {
case GCRY_MD_SHA1:
curve = _aacs1_curve();
key_len = 20;
break;
default:
BD_ASSERT_UNREACHABLE ("invalid signature size");
return 0;
}
GCRY_VERIFY("_aacs_sexp_key",
_aacs_sexp_key(&sexp_key, q_x, q_y, NULL));
_aacs_sexp_key(&sexp_key, q_x, q_y, NULL, curve, key_len));
GCRY_VERIFY("_aacs_sexp_sha1",
_aacs_sexp_sha1(&sexp_data, data, len));
GCRY_VERIFY("_aacs_sexp_hash",
_aacs_sexp_hash(&sexp_data, data, len, hash_type));
GCRY_VERIFY("_aacs_sexp_signature",
_aacs_sexp_signature(&sexp_sig, signature));
_aacs_sexp_signature(&sexp_sig, signature, key_len));
GCRY_VERIFY("gcry_pk_verify",
gcry_pk_verify(sexp_sig, sexp_data, sexp_key));
......@@ -532,7 +567,7 @@ static int _aacs_verify(const uint8_t *signature,
int crypto_aacs_verify(const uint8_t *cert, const uint8_t *signature, const uint8_t *data, uint32_t len)
{
return !_aacs_verify(signature, cert + 12, cert + 32, data, len);
return !_aacs_verify(signature, GCRY_MD_SHA1, cert + 12, cert + 32, data, len);
}
int crypto_aacs_verify_aacsla(const uint8_t *signature, const uint8_t *data, uint32_t len)
......@@ -542,7 +577,7 @@ int crypto_aacs_verify_aacsla(const uint8_t *signature, const uint8_t *data, ui
static const uint8_t aacs_la_pubkey_y[] = {0x13, 0x7E, 0xC6, 0x38, 0x81, 0x8F, 0xD9, 0x8F, 0xA4, 0xC3,
0x0B, 0x99, 0x67, 0x28, 0xBF, 0x4B, 0x91, 0x7F, 0x6A, 0x27 };
return !_aacs_verify(signature, aacs_la_pubkey_x, aacs_la_pubkey_y, data, len);
return !_aacs_verify(signature, GCRY_MD_SHA1, aacs_la_pubkey_x, aacs_la_pubkey_y, data, len);
}
int crypto_aacs_verify_aacscc(const uint8_t *signature, const uint8_t *data, uint32_t len)
......@@ -552,7 +587,7 @@ int crypto_aacs_verify_aacscc(const uint8_t *signature, const uint8_t *data, ui
static const uint8_t aacs_cc_pubkey_y[] = { 0x00, 0x1D, 0xF3, 0x6B, 0x8F, 0x2E, 0xCF, 0x83, 0xCD, 0xEE,
0x43, 0x8F, 0x7F, 0xD1, 0xF4, 0x80, 0x6F, 0xD2, 0x0D, 0xE7 };
return !_aacs_verify(signature, aacs_cc_pubkey_x, aacs_cc_pubkey_y, data, len);
return !_aacs_verify(signature, GCRY_MD_SHA1, aacs_cc_pubkey_x, aacs_cc_pubkey_y, data, len);
}
static int crypto_aacs_verify_cert(const uint8_t *cert)
......
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