This series adds support for the NIST P521 curve to the ecdsa module
to enable signature verification with it.
An issue with the current code in ecdsa is that it assumes that input
arrays providing key coordinates for example, are arrays of digits
(a 'digit' is a 'u64'). This works well for all currently supported
curves, such as NIST P192/256/384, but does not work for NIST P521 where
coordinates are 8 digits + 2 bytes long. So some of the changes deal with
converting byte arrays to digits and adjusting tests on input byte
array lengths to tolerate arrays not providing multiples of 8 bytes.
Regards,
Stefan
v8:
- Changed nbits from unsigned int to u32 (5/13)
- Added MODULE_ALIAS_CRYPTO("ecdsa-nist-p521") (11/13)
- Applied R-b & T-b tags from Jarkko
- Rebased on master branch at
https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
v7:
- Applied T-b tag from Christian to all patches
- Applied R-b tag from Jarkko to some patches
- Rephrased some patch descriptions per Jarkko's request
v6:
- Use existing #defines for number of digits rather than plain numbers
(1/13, 6/13) following Bharat's suggestion
- Initialize result from lowest 521 bits of product rather than going
through tmp variable (6/13)
v5:
- Simplified ecc_digits_from_bytes as suggested by Lukas (1/12)
- Using nbits == 521 to detect NIST P521 curve rather than strcmp()
(5,6/12)
- Nits in patch description and comments (11/12)
v4:
- Followed suggestions by Lukas Wummer (1,5,8/12)
- Use nbits rather than ndigits where needed (8/12)
- Renaming 'keylen' variablest to bufsize where necessary (9/12)
- Adjust signature size calculation for NIST P521 (11/12)
v3:
- Dropped ecdh support
- Use ecc_get_curve_nbits for getting number of bits in NIST P521 curve
in ecc_point_mult (7/10)
v2:
- Reformulated some patch descriptions
- Fixed issue detected by krobot
- Some other small changes to the code
Stefan Berger (13):
crypto: ecc - Use ECC_CURVE_NIST_P192/256/384_DIGITS where possible
crypto: ecdsa - Convert byte arrays with key coordinates to digits
crypto: ecdsa - Adjust tests on length of key parameters
crypto: ecdsa - Extend res.x mod n calculation for NIST P521
crypto: ecc - Add nbits field to ecc_curve structure
crypto: ecc - Implement vli_mmod_fast_521 for NIST p521
crypto: ecc - Add special case for NIST P521 in ecc_point_mult
crypto: ecc - Add NIST P521 curve parameters
crypto: ecdsa - Replace ndigits with nbits where precision is needed
crypto: ecdsa - Rename keylen to bufsize where necessary
crypto: ecdsa - Register NIST P521 and extend test suite
crypto: asymmetric_keys - Adjust signature size calculation for NIST
P521
crypto: x509 - Add OID for NIST P521 and extend parser for it
crypto/asymmetric_keys/public_key.c | 14 ++-
crypto/asymmetric_keys/x509_cert_parser.c | 3 +
crypto/ecc.c | 44 +++++--
crypto/ecc_curve_defs.h | 49 ++++++++
crypto/ecdsa.c | 63 +++++++---
crypto/ecrdsa_defs.h | 5 +
crypto/testmgr.c | 7 ++
crypto/testmgr.h | 146 ++++++++++++++++++++++
include/crypto/ecc_curve.h | 2 +
include/crypto/ecdh.h | 1 +
include/crypto/internal/ecc.h | 24 +++-
include/linux/oid_registry.h | 1 +
12 files changed, 336 insertions(+), 23 deletions(-)
base-commit: a9a72140536fe02d98bce72a608ccf3ba9008a71
--
2.43.0
Implement vli_mmod_fast_521 following the description for how to calculate
the modulus for NIST P521 in the NIST publication "Recommendations for
Discrete Logarithm-Based Cryptography: Elliptic Curve Domain Parameters"
section G.1.4.
NIST p521 requires 9 64bit digits, so increase the ECC_MAX_DIGITS so that
the vli digit array provides enough elements to fit the larger integers
required by this curve.
Tested-by: Lukas Wunner <[email protected]>
Reviewed-by: Jarkko Sakkinen <[email protected]>
Signed-off-by: Stefan Berger <[email protected]>
---
crypto/ecc.c | 25 +++++++++++++++++++++++++
include/crypto/internal/ecc.h | 3 ++-
2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/crypto/ecc.c b/crypto/ecc.c
index 01aa70e97e55..90a8c7ea9095 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -902,6 +902,28 @@ static void vli_mmod_fast_384(u64 *result, const u64 *product,
#undef AND64H
#undef AND64L
+/*
+ * Computes result = product % curve_prime
+ * from "Recommendations for Discrete Logarithm-Based Cryptography:
+ * Elliptic Curve Domain Parameters" section G.1.4
+ */
+static void vli_mmod_fast_521(u64 *result, const u64 *product,
+ const u64 *curve_prime, u64 *tmp)
+{
+ const unsigned int ndigits = ECC_CURVE_NIST_P521_DIGITS;
+ size_t i;
+
+ /* Initialize result with lowest 521 bits from product */
+ vli_set(result, product, ndigits);
+ result[8] &= 0x1ff;
+
+ for (i = 0; i < ndigits; i++)
+ tmp[i] = (product[8 + i] >> 9) | (product[9 + i] << 55);
+ tmp[8] &= 0x1ff;
+
+ vli_mod_add(result, result, tmp, curve_prime, ndigits);
+}
+
/* Computes result = product % curve_prime for different curve_primes.
*
* Note that curve_primes are distinguished just by heuristic check and
@@ -941,6 +963,9 @@ static bool vli_mmod_fast(u64 *result, u64 *product,
case ECC_CURVE_NIST_P384_DIGITS:
vli_mmod_fast_384(result, product, curve_prime, tmp);
break;
+ case ECC_CURVE_NIST_P521_DIGITS:
+ vli_mmod_fast_521(result, product, curve_prime, tmp);
+ break;
default:
pr_err_ratelimited("ecc: unsupported digits size!\n");
return false;
diff --git a/include/crypto/internal/ecc.h b/include/crypto/internal/ecc.h
index ab722a8986b7..4e2f5f938e91 100644
--- a/include/crypto/internal/ecc.h
+++ b/include/crypto/internal/ecc.h
@@ -33,7 +33,8 @@
#define ECC_CURVE_NIST_P192_DIGITS 3
#define ECC_CURVE_NIST_P256_DIGITS 4
#define ECC_CURVE_NIST_P384_DIGITS 6
-#define ECC_MAX_DIGITS (512 / 64) /* due to ecrdsa */
+#define ECC_CURVE_NIST_P521_DIGITS 9
+#define ECC_MAX_DIGITS DIV_ROUND_UP(521, 64) /* NIST P521 */
#define ECC_DIGITS_TO_BYTES_SHIFT 3
--
2.43.0
In cases where 'keylen' was referring to the size of the buffer used by
a curve's digits, it does not reflect the purpose of the variable anymore
once NIST P521 is used. What it refers to then is the size of the buffer,
which may be a few bytes larger than the size a coordinate of a key.
Therefore, rename keylen to bufsize where appropriate.
Tested-by: Lukas Wunner <[email protected]>
Reviewed-by: Jarkko Sakkinen <[email protected]>
Signed-off-by: Stefan Berger <[email protected]>
---
crypto/ecdsa.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
index 75d3eea885db..c7923f30661b 100644
--- a/crypto/ecdsa.c
+++ b/crypto/ecdsa.c
@@ -35,8 +35,8 @@ struct ecdsa_signature_ctx {
static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
const void *value, size_t vlen, unsigned int ndigits)
{
- size_t keylen = ndigits * sizeof(u64);
- ssize_t diff = vlen - keylen;
+ size_t bufsize = ndigits * sizeof(u64);
+ ssize_t diff = vlen - bufsize;
const char *d = value;
u8 rs[ECC_MAX_BYTES];
@@ -58,7 +58,7 @@ static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
if (diff)
return -EINVAL;
}
- if (-diff >= keylen)
+ if (-diff >= bufsize)
return -EINVAL;
if (diff) {
@@ -138,7 +138,7 @@ static int ecdsa_verify(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
- size_t keylen = ctx->curve->g.ndigits * sizeof(u64);
+ size_t bufsize = ctx->curve->g.ndigits * sizeof(u64);
struct ecdsa_signature_ctx sig_ctx = {
.curve = ctx->curve,
};
@@ -165,14 +165,14 @@ static int ecdsa_verify(struct akcipher_request *req)
goto error;
/* if the hash is shorter then we will add leading zeros to fit to ndigits */
- diff = keylen - req->dst_len;
+ diff = bufsize - req->dst_len;
if (diff >= 0) {
if (diff)
memset(rawhash, 0, diff);
memcpy(&rawhash[diff], buffer + req->src_len, req->dst_len);
} else if (diff < 0) {
/* given hash is longer, we take the left-most bytes */
- memcpy(&rawhash, buffer + req->src_len, keylen);
+ memcpy(&rawhash, buffer + req->src_len, bufsize);
}
ecc_swap_digits((u64 *)rawhash, hash, ctx->curve->g.ndigits);
--
2.43.0