From: Hongbo Li <herberthbli@xxxxxxxxxxx> This patch adds the support of eddsa(currently ed25519) verification which is described in RFC8032 section 5.1.7 [1]. [1]: https://tools.ietf.org/html/rfc8032#section-5.1.7 Signed-off-by: Hongbo Li <herberthbli@xxxxxxxxxxx> --- crypto/Kconfig | 11 ++ crypto/Makefile | 3 + crypto/eddsa.c | 326 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 340 insertions(+) create mode 100644 crypto/eddsa.c diff --git a/crypto/Kconfig b/crypto/Kconfig index f684513..c7f4d7a 100644 --- a/crypto/Kconfig +++ b/crypto/Kconfig @@ -268,6 +268,17 @@ config CRYPTO_ECRDSA config CRYPTO_EC_MPI tristate +config CRYPTO_EDDSA + tristate "EDDSA (ed25519) algorithm" + select CRYPTO_ECC + select CRYPTO_EC_MPI + select CRYPTO_AKCIPHER + select ASN1 + help + Edwards-curve Digital Signature Algorithm (ed25519) is a variant + of Schnorr's signature system with (possibly twisted) Edwards curves. + Only signature verification is implemented. + config CRYPTO_SM2 tristate "SM2 algorithm" select CRYPTO_SM3 diff --git a/crypto/Makefile b/crypto/Makefile index 837aa1d..bae62d2 100644 --- a/crypto/Makefile +++ b/crypto/Makefile @@ -56,6 +56,9 @@ ecdsa_generic-y += ecdsa.o ecdsa_generic-y += ecdsasignature.asn1.o obj-$(CONFIG_CRYPTO_ECDSA) += ecdsa_generic.o +eddsa_generic-y += eddsa.o +obj-$(CONFIG_CRYPTO_EDDSA) += eddsa_generic.o + crypto_acompress-y := acompress.o crypto_acompress-y += scompress.o obj-$(CONFIG_CRYPTO_ACOMP2) += crypto_acompress.o diff --git a/crypto/eddsa.c b/crypto/eddsa.c new file mode 100644 index 0000000..e9eec55 --- /dev/null +++ b/crypto/eddsa.c @@ -0,0 +1,326 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * EDDSA generic algorithm. + * + * Copyright (c) 2021 Hongbo Li <herberthbli@xxxxxxxxxxx> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + */ + +#include <linux/mpi.h> +#include <linux/module.h> +#include <linux/oid_registry.h> +#include <crypto/hash.h> +#include <crypto/sha2.h> +#include <crypto/ecdh.h> +#include <crypto/curve25519.h> +#include <crypto/internal/akcipher.h> +#include "ec_mpi.h" + +struct eddsa_ctx { + enum OID algo_oid; + struct mpi_ec_ctx ec_ctx; +}; + +static MPI p58; +static MPI seven; +static MPI m1; + +static const struct ecc_domain_parms ed25519_domain_params = { + .desc = "ed25519", + .nbits = 256, + .fips = 0, + .model = MPI_EC_EDWARDS, + .dialect = ECC_DIALECT_ED25519, + .p = "0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFED", + .a = "-0x01", + .b = "-0x2DFC9311D490018C7338BF8688861767FF8FF5B2BEBE27548A14B235ECA6874A", + .n = "0x1000000000000000000000000000000014DEF9DEA2F79CD65812631A5CF5D3ED", + .g_x = "0x216936D3CD6E53FEC0A4E231FDD6DC5C692CC7609525A7B2C9562D608F25D51A", + .g_y = "0x6666666666666666666666666666666666666666666666666666666666666658", + .h = 8, +}; + +static void reverse_buffer(u8 *buffer, u32 length) +{ + u32 tmp, i; + + for (i = 0; i < length / 2; i++) { + tmp = buffer[i]; + buffer[i] = buffer[length - 1 - i]; + buffer[length - 1 - i] = tmp; + } +} + +static int eddsa_encode_x_y(MPI x, MPI y, u8 *buf, u32 key_size) +{ + memcpy(buf, y->d, key_size); + if (mpi_test_bit(x, 0)) + buf[key_size - 1] |= 0x80; + + return 0; +} + +static int ecc_eddsa_encodepoint(MPI_POINT point, struct mpi_ec_ctx *ec, + MPI x, MPI y, u8 *buf, u32 key_size) +{ + if (mpi_ec_get_affine(x, y, point, ec)) + return -EINVAL; + + return eddsa_encode_x_y(x, y, buf, key_size); +} + +/* Recover X from Y and SIGN (which actually is a parity bit). */ +static int eddsa_recover_x(MPI x, MPI y, int sign, struct mpi_ec_ctx *ec) +{ + MPI u, v, v3, t; + int ret = 0; + + if (ec->dialect != ECC_DIALECT_ED25519) + return -ENOPKG; + + u = mpi_new(0); + v = mpi_new(0); + v3 = mpi_new(0); + t = mpi_new(0); + + /* Compute u and v */ + /* u = y^2 */ + mpi_mulm(u, y, y, ec->p); + /* v = b*y^2 */ + mpi_mulm(v, ec->b, u, ec->p); + /* u = y^2-1 */ + mpi_sub_ui(u, u, 1); + /* v = b*y^2+1 */ + mpi_add_ui(v, v, 1); + + /* Compute sqrt(u/v) */ + /* v3 = v^3 */ + mpi_powm(v3, v, mpi_const(MPI_C_THREE), ec->p); + /* t = v3 * v3 * u * v = u * v^7 */ + mpi_powm(t, v, seven, ec->p); + mpi_mulm(t, t, u, ec->p); + /* t = t^((p-5)/8) = (u * v^7)^((p-5)/8) */ + mpi_powm(t, t, p58, ec->p); + /* x = t * u * v^3 = (u * v^3) * (u * v^7)^((p-5)/8) */ + mpi_mulm(t, t, u, ec->p); + mpi_mulm(x, t, v3, ec->p); + + /* Adjust if needed. */ + /* t = v * x^2 */ + mpi_mulm(t, x, x, ec->p); + mpi_mulm(t, t, v, ec->p); + /* -t == u ? x = x * sqrt(-1) */ + mpi_sub(t, ec->p, t); + if (!mpi_cmp(t, u)) { + mpi_mulm(x, x, m1, ec->p); + /* t = v * x^2 */ + mpi_mulm(t, x, x, ec->p); + mpi_mulm(t, t, v, ec->p); + /* -t == u ? x = x * sqrt(-1) */ + mpi_sub(t, ec->p, t); + if (!mpi_cmp(t, u)) + ret = -EINVAL; + } + + /* Choose the desired square root according to parity */ + if (mpi_test_bit(x, 0) != !!sign) + mpi_sub(x, ec->p, x); + + mpi_free(t); + mpi_free(v3); + mpi_free(v); + mpi_free(u); + + return ret; +} + +static int ecc_eddsa_decodepoint(const u8 *pk, int key_size, + struct mpi_ec_ctx *ec, MPI_POINT result) +{ + MPI y; + u8 *rawmpi; + int sign, ret = 0; + + rawmpi = kmalloc(key_size, GFP_KERNEL); + if (!rawmpi) + return -ENOMEM; + memcpy(rawmpi, pk, key_size); + reverse_buffer(rawmpi, key_size); + + sign = !!(rawmpi[0] & 0x80); + rawmpi[0] &= 0x7f; + + y = mpi_read_raw_data(rawmpi, key_size); + if (!y) { + ret = -EINVAL; + goto out; + } + + mpi_normalize(y); + mpi_set(result->y, y); + mpi_free(y); + + ret = eddsa_recover_x(result->x, result->y, sign, ec); + mpi_set_ui(result->z, 1); +out: + kfree(rawmpi); + return ret; +} + +static int eddsa_verify(struct akcipher_request *req) +{ + struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req); + struct eddsa_ctx *ctx = akcipher_tfm_ctx(tfm); + struct mpi_ec_ctx *ec = &ctx->ec_ctx; + struct gcry_mpi_point sb, ka; + MPI s = NULL; + MPI k = NULL; + u8 sig[CURVE25519_KEY_SIZE * 2], digest[SHA512_DIGEST_SIZE]; + u8 *buf; + u32 key_size; + int ret = 0; + + if (ctx->algo_oid != OID_ed25519) + return -ENOPKG; + + key_size = CURVE25519_KEY_SIZE; + + if (!ec->Q || req->src_len != key_size * 2) + return -EINVAL; + + sg_copy_to_buffer(req->src, sg_nents_for_len(req->src, req->src_len), + sig, req->src_len); + + sg_pcopy_to_buffer(req->src, + sg_nents_for_len(req->src, + req->src_len + req->dst_len), + digest, req->dst_len, req->src_len); + + reverse_buffer(digest, SHA512_DIGEST_SIZE); + k = mpi_read_raw_data(digest, SHA512_DIGEST_SIZE); + + reverse_buffer(sig + key_size, key_size); + s = mpi_read_raw_data(sig + key_size, key_size); + + mpi_point_init(&sb); + mpi_point_init(&ka); + + mpi_ec_mul_point(&sb, s, ec->G, ec); + mpi_ec_mul_point(&ka, k, ec->Q, ec); + mpi_sub(ka.x, ec->p, ka.x); + mpi_ec_add_points(&sb, &sb, &ka, ec); + + buf = kmalloc(key_size, GFP_KERNEL); + if (!buf) { + ret = -ENOMEM; + goto out; + } + + ret = ecc_eddsa_encodepoint(&sb, ec, s, k, buf, key_size); + if (ret) + goto out; + + if (memcmp(buf, sig, key_size)) + ret = -EKEYREJECTED; + +out: + mpi_point_free_parts(&sb); + mpi_point_free_parts(&ka); + mpi_free(k); + mpi_free(s); + kfree(buf); + return ret; +} + +static int eddsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, + unsigned int keylen) +{ + struct eddsa_ctx *ctx = akcipher_tfm_ctx(tfm); + struct mpi_ec_ctx *ec = &ctx->ec_ctx; + const u8 *pk = key; + + if (ctx->algo_oid != OID_ed25519) + return -ENOPKG; + + if (keylen != CURVE25519_KEY_SIZE) + return -EINVAL; + + return ecc_eddsa_decodepoint(pk, keylen, ec, ec->Q); +} + +static u32 eddsa_max_size(struct crypto_akcipher *tfm) +{ + struct eddsa_ctx *ctx = akcipher_tfm_ctx(tfm); + + if (ctx->algo_oid == OID_ed25519) + return CURVE25519_KEY_SIZE; + + return 0; +} + +static int eddsa_25519_init_tfm(struct crypto_akcipher *tfm) +{ + struct eddsa_ctx *ctx = akcipher_tfm_ctx(tfm); + + ctx->algo_oid = OID_ed25519; + p58 = mpi_scanval("0FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD"); + if (!p58) + return -ENOMEM; + + m1 = mpi_scanval("2B8324804FC1DF0B2B4D00993DFBD7A72F431806AD2FE478C4EE1B274A0EA0B0"); + if (!m1) + return -ENOMEM; + + seven = mpi_set_ui(NULL, 7); + + return ec_mpi_ctx_init(&ctx->ec_ctx, &ed25519_domain_params); +} + +static void eddsa_exit_tfm(struct crypto_akcipher *tfm) +{ + struct eddsa_ctx *ctx = akcipher_tfm_ctx(tfm); + + ec_mpi_ctx_deinit(&ctx->ec_ctx); + mpi_free(p58); + mpi_free(seven); + mpi_free(m1); +} + + +static struct akcipher_alg eddsa_25519 = { + .verify = eddsa_verify, + .set_pub_key = eddsa_set_pub_key, + .max_size = eddsa_max_size, + .init = eddsa_25519_init_tfm, + .exit = eddsa_exit_tfm, + .base = { + .cra_name = "eddsa-25519", + .cra_driver_name = "eddsa-25519-generic", + .cra_priority = 100, + .cra_module = THIS_MODULE, + .cra_ctxsize = sizeof(struct eddsa_ctx), + }, +}; + +static int eddsa_mod_init(void) +{ + return crypto_register_akcipher(&eddsa_25519); +} + +static void eddsa_mod_exit(void) +{ + crypto_unregister_akcipher(&eddsa_25519); +} + +module_init(eddsa_mod_init); +module_exit(eddsa_mod_exit); + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Hongbo Li <herberthbli@xxxxxxxxxxx>"); +MODULE_ALIAS_CRYPTO("eddsa"); +MODULE_ALIAS_CRYPTO("eddsa-generic"); +MODULE_DESCRIPTION("EDDSA generic algorithm"); -- 1.8.3.1
