1 files changed, 324 insertions, 0 deletions
diff --git a/crypto/sm2/sm2_sign.c b/crypto/sm2/sm2_sign.c
new file mode 100644
index 0000000000..2d311d9046
--- /dev/null
+++ b/crypto/sm2/sm2_sign.c
@@ -0,0 +1,324 @@
+/*
+ * Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2017 Ribose Inc. All Rights Reserved.
+ * Ported from Ribose contributions from Botan.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/sm2.h>
+#include <openssl/evp.h>
+#include <openssl/bn.h>
+#include <string.h>
+
+static BIGNUM *compute_msg_hash(const EVP_MD *digest,
+                                const EC_KEY *key,
+                                const char *user_id,
+                                const uint8_t *msg, size_t msg_len)
+{
+    EVP_MD_CTX *hash = EVP_MD_CTX_new();
+    const int md_size = EVP_MD_size(digest);
+    uint8_t *za = OPENSSL_zalloc(md_size);
+    BIGNUM *e = NULL;
+
+    if (za == NULL)
+        goto done;
+
+    if (hash == NULL)
+        goto done;
+
+    if (SM2_compute_userid_digest(za, digest, user_id, key) == 0)
+        goto done;
+
+    if (EVP_DigestInit(hash, digest) == 0)
+        goto done;
+
+    if (EVP_DigestUpdate(hash, za, md_size) == 0)
+        goto done;
+
+    if (EVP_DigestUpdate(hash, msg, msg_len) == 0)
+        goto done;
+
+    /* reuse za buffer to hold H(ZA || M) */
+    if (EVP_DigestFinal(hash, za, NULL) == 0)
+        goto done;
+
+    e = BN_bin2bn(za, md_size, NULL);
+
+ done:
+    OPENSSL_free(za);
+    EVP_MD_CTX_free(hash);
+    return e;
+}
+
+static
+ECDSA_SIG *SM2_sig_gen(const EC_KEY *key, const BIGNUM *e)
+{
+    const BIGNUM *dA = EC_KEY_get0_private_key(key);
+    const EC_GROUP *group = EC_KEY_get0_group(key);
+    const BIGNUM *order = EC_GROUP_get0_order(group);
+
+    ECDSA_SIG *sig = NULL;
+    EC_POINT *kG = NULL;
+    BN_CTX *ctx = NULL;
+    BIGNUM *k = NULL;
+    BIGNUM *rk = NULL;
+    BIGNUM *r = NULL;
+    BIGNUM *s = NULL;
+    BIGNUM *x1 = NULL;
+    BIGNUM *tmp = NULL;
+
+    kG = EC_POINT_new(group);
+    if (kG == NULL)
+        goto done;
+
+    ctx = BN_CTX_new();
+    if (ctx == NULL)
+        goto done;
+
+    BN_CTX_start(ctx);
+
+    k = BN_CTX_get(ctx);
+    rk = BN_CTX_get(ctx);
+    x1 = BN_CTX_get(ctx);
+    tmp = BN_CTX_get(ctx);
+
+    if (tmp == NULL)
+        goto done;
+
+    /* These values are returned and so should not be allocated out of the context */
+    r = BN_new();
+    s = BN_new();
+
+    if (r == NULL || s == NULL)
+        goto done;
+
+    for (;;) {
+        BN_priv_rand_range(k, order);
+
+        if (EC_POINT_mul(group, kG, k, NULL, NULL, ctx) == 0)
+            goto done;
+
+        if (EC_POINT_get_affine_coordinates_GFp(group, kG, x1, NULL, ctx) == 0)
+            goto done;
+
+        if (BN_mod_add(r, e, x1, order, ctx) == 0)
+            goto done;
+
+        /* try again if r == 0 or r+k == n */
+        if (BN_is_zero(r))
+            continue;
+
+        BN_add(rk, r, k);
+
+        if (BN_cmp(rk, order) == 0)
+            continue;
+
+        BN_add(s, dA, BN_value_one());
+        BN_mod_inverse(s, s, order, ctx);
+
+        BN_mod_mul(tmp, dA, r, order, ctx);
+        BN_sub(tmp, k, tmp);
+
+        BN_mod_mul(s, s, tmp, order, ctx);
+
+        sig = ECDSA_SIG_new();
+
+        if (sig == NULL)
+            goto done;
+
+         /* takes ownership of r and s */
+        ECDSA_SIG_set0(sig, r, s);
+        break;
+    }
+
+ done:
+
+    if (sig == NULL) {
+        BN_free(r);
+        BN_free(s);
+    }
+
+    BN_CTX_free(ctx);
+    EC_POINT_free(kG);
+    return sig;
+
+}
+
+static
+int SM2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig, const BIGNUM *e)
+{
+    int ret = 0;
+    const EC_GROUP *group = EC_KEY_get0_group(key);
+    const BIGNUM *order = EC_GROUP_get0_order(group);
+    BN_CTX *ctx = NULL;
+    EC_POINT *pt = NULL;
+
+    BIGNUM *t = NULL;
+    BIGNUM *x1 = NULL;
+    const BIGNUM *r = NULL;
+    const BIGNUM *s = NULL;
+
+    ctx = BN_CTX_new();
+    if (ctx == NULL)
+        goto done;
+    pt = EC_POINT_new(group);
+    if (pt == NULL)
+        goto done;
+
+    BN_CTX_start(ctx);
+
+    t = BN_CTX_get(ctx);
+    x1 = BN_CTX_get(ctx);
+
+    if (x1 == NULL)
+        goto done;
+
+    /*
+       B1: verify whether r' in [1,n-1], verification failed if not
+       B2: vefify whether s' in [1,n-1], verification failed if not
+       B3: set M'~=ZA || M'
+       B4: calculate e'=Hv(M'~)
+       B5: calculate t = (r' + s') modn, verification failed if t=0
+       B6: calculate the point (x1', y1')=[s']G + [t]PA
+       B7: calculate R=(e'+x1') modn, verfication pass if yes, otherwise failed
+     */
+
+    ECDSA_SIG_get0(sig, &r, &s);
+
+    if (BN_cmp(r, BN_value_one()) < 0)
+        goto done;
+    if (BN_cmp(s, BN_value_one()) < 0)
+        goto done;
+
+    if (BN_cmp(order, r) <= 0)
+        goto done;
+    if (BN_cmp(order, s) <= 0)
+        goto done;
+
+    if (BN_mod_add(t, r, s, order, ctx) == 0)
+        goto done;
+
+    if (BN_is_zero(t) == 1)
+        goto done;
+
+    if (EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx) == 0)
+        goto done;
+
+    if (EC_POINT_get_affine_coordinates_GFp(group, pt, x1, NULL, ctx) == 0)
+        goto done;
+
+    if (BN_mod_add(t, e, x1, order, ctx) == 0)
+        goto done;
+
+    if (BN_cmp(r, t) == 0)
+        ret = 1;
+
+ done:
+    EC_POINT_free(pt);
+    BN_CTX_free(ctx);
+    return ret;
+}
+
+ECDSA_SIG *SM2_do_sign(const EC_KEY *key,
+                       const EVP_MD *digest,
+                       const char *user_id, const uint8_t *msg, size_t msg_len)
+{
+    BIGNUM *e = NULL;
+    ECDSA_SIG *sig = NULL;
+
+    e = compute_msg_hash(digest, key, user_id, msg, msg_len);
+    if (e == NULL)
+        goto done;
+
+    sig = SM2_sig_gen(key, e);
+
+ done:
+    BN_free(e);
+    return sig;
+}
+
+int SM2_do_verify(const EC_KEY *key,
+                  const EVP_MD *digest,
+                  const ECDSA_SIG *sig,
+                  const char *user_id, const uint8_t *msg, size_t msg_len)
+{
+    BIGNUM *e = NULL;
+    int ret = -1;
+
+    e = compute_msg_hash(digest, key, user_id, msg, msg_len);
+    if (e == NULL)
+        goto done;
+
+    ret = SM2_sig_verify(key, sig, e);
+
+ done:
+    BN_free(e);
+    return ret;
+}
+
+int SM2_sign(int type, const unsigned char *dgst, int dgstlen,
+             unsigned char *sig, unsigned int *siglen, EC_KEY *eckey)
+{
+    BIGNUM *e = NULL;
+    ECDSA_SIG *s = NULL;
+    int ret = -1;
+
+    if (type != NID_sm3)
+        goto done;
+
+    if (dgstlen != 32)          /* expected length of SM3 hash */
+        goto done;
+
+    e = BN_bin2bn(dgst, dgstlen, NULL);
+
+    s = SM2_sig_gen(eckey, e);
+
+    *siglen = i2d_ECDSA_SIG(s, &sig);
+
+    ECDSA_SIG_free(s);
+
+    ret = 0;
+
+ done:
+    ECDSA_SIG_free(s);
+    BN_free(e);
+    return ret;
+}
+
+int SM2_verify(int type, const unsigned char *dgst, int dgstlen,
+               const unsigned char *sig, int sig_len, EC_KEY *eckey)
+{
+    ECDSA_SIG *s = NULL;
+    BIGNUM *e = NULL;
+    const unsigned char *p = sig;
+    unsigned char *der = NULL;
+    int derlen = -1;
+    int ret = -1;
+
+    if (type != NID_sm3)
+        goto done;
+
+    s = ECDSA_SIG_new();
+    if (s == NULL)
+        goto done;
+    if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
+        goto done;
+    /* Ensure signature uses DER and doesn't have trailing garbage */
+    derlen = i2d_ECDSA_SIG(s, &der);
+    if (derlen != sig_len || memcmp(sig, der, derlen) != 0)
+        goto done;
+
+    e = BN_bin2bn(dgst, dgstlen, NULL);
+
+    ret = SM2_sig_verify(eckey, s, e);
+
+ done:
+    OPENSSL_free(der);
+    BN_free(e);
+    ECDSA_SIG_free(s);
+    return ret;
+}