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SubjectRe: [RFC PATCH 4/4] crypto: Add EC-RDSA algorithm
Date
Am Sonntag, 6. Januar 2019, 14:36:08 CET schrieb Vitaly Chikunov:

Hi Vitaly,

> Add Elliptic Curve Russian Digital Signature Algorithm (GOST R
> 34.10-2012, RFC 7091, ISO/IEC 14888-3) is one of the Russian (and since
> 2018 the CIS countries) cryptographic standard algorithms (called GOST
> algorithms). Only signature verification is supported, with intent to be
> used in the IMA.

Do you happen to have test vectors for the testmgr?


> +
> +/* Parse DER encoded subjectPublicKey. */
> +static int ecrdsa_set_pub_key(struct crypto_akcipher *tfm, const void *ber,
> + unsigned int len)
> +{
> + struct ecrdsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> + unsigned int ndigits;
> + const u8 *k = ber;
> + unsigned int offset;
> +
> + /* First chance to zero ctx */
> + memset(ctx, 0, sizeof(*ctx));
> +
> + if (len < 3 ||
> + k[0] != 0x04 || /* OCTET STRING */
> + (k[1] < 0x80 && len != k[1] + 2) ||
> + (k[1] == 0x81 && len != k[2] + 3) ||
> + k[1] > 0x81)
> + return -EBADMSG;
> + offset = (k[1] < 0x80)? 2 : 3;
> + k += offset;
> + len -= offset;

Why do you manually parse the ASN.1 structure instead of using the ASN.1
parser?

> + /* Key is two 256- or 512-bit coordinates. */
> + if (len != (2 * 256 / 8) &&
> + len != (2 * 512 / 8))
> + return -ENOPKG;
> + ndigits = len / sizeof(u64) / 2;
> + ctx->pub_key = ECC_POINT_INIT(ctx->_pubp[0], ctx->_pubp[1], ndigits);
> + vli_from_le64(ctx->pub_key.x, k, ndigits);
> + vli_from_le64(ctx->pub_key.y, k + ndigits * sizeof(u64), ndigits);
> +
> + return 0;
> +}
> +
> +/* Parse DER encoded SubjectPublicKeyInfo.AlgorithmIdentifier.parameters.
> */ +static int ecrdsa_set_params(struct crypto_akcipher *tfm, enum OID
> algo, + const void *params, unsigned int paramlen)
> +{
> + struct ecrdsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> + const u8 *p = params;
> + int i;
> +
> + if (algo == OID_gost2012PublicKey256) {
> + ctx->digest = "streebog256";
> + ctx->digest_oid = OID_gost2012Digest256;
> + ctx->digest_len = 256 / 8;
> + } else if (algo == OID_gost2012PublicKey512) {
> + ctx->digest = "streebog512";
> + ctx->digest_oid = OID_gost2012Digest512;
> + ctx->digest_len = 512 / 8;
> + } else
> + return -ENOPKG;
> + ctx->curve = NULL;
> + ctx->curve_oid = 0;
> + ctx->algo_oid = algo;
> +
> + for (i = 0; i < paramlen; i += p[i + 1] + 2) {
> + const struct ecc_curve *curve;
> + enum OID oid;
> +
> + if (paramlen - i < 2 ||
> + p[i] != 0x06 || /* OBJECT IDENTIFIER */

Same here and in the following

> + p[i + 1] > paramlen - i - 2)
> + return -EBADMSG;
> + oid = look_up_OID(p + i + 2, p[i + 1]);
> + if (oid == OID__NR)
> + return -ENOPKG;
> +
> + if (oid == OID_gost2012Digest256 ||
> + oid == OID_gost2012Digest512) {
> + if (oid != ctx->digest_oid)
> + return -ENOPKG;
> + } else {
> + curve = get_curve_by_oid(oid);
> + if (!curve || ctx->curve)
> + return -ENOPKG;
> + ctx->curve = curve;
> + ctx->curve_oid = oid;
> + }
> + }
> + /* Sizes of algo, curve, pub_key, and digest should match each other. */
> + if (!ctx->curve ||
> + ctx->curve->g.ndigits * sizeof(u64) != ctx->digest_len ||
> + ctx->curve->g.ndigits != ctx->pub_key.ndigits)
> + return -ENOPKG;
> +
> + /* First chance to validate the public key. */
> + if (ecc_is_pubkey_valid_partial(ctx->curve, &ctx->pub_key))
> + return -EKEYREJECTED;
> +
> + return 0;
> +}
> +

> +MODULE_ALIAS_CRYPTO("ecrdsa");

I do not think you need that alias as the module name already will be named
this way. I guess you rather should add ecrdsa-generic as module alias.



Ciao
Stephan


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