refactor ecc_sign_hash_ex

Author: karel-m

src/headers/tomcrypt_pk.h

@@ -337,23 +337,33 @@ int  ecc_decrypt_key(const unsigned char *in,  unsigned long  inlen,
                            unsigned char *out, unsigned long *outlen,
                            const ecc_key *key);
 
-#define ecc_sign_hash_rfc7518(in_, inlen_, out_, outlen_, prng_, wprng_, key_) \
-   ecc_sign_hash_ex(in_, inlen_, out_, outlen_, prng_, wprng_, LTC_ECCSIG_RFC7518, NULL, key_)
+int ecc_sign_hash(const unsigned char *in,  unsigned long inlen,
+                  unsigned char *out, unsigned long *outlen,
+                  prng_state *prng, int wprng, const ecc_key *key);
 
-#define ecc_sign_hash(in_, inlen_, out_, outlen_, prng_, wprng_, key_) \
-   ecc_sign_hash_ex(in_, inlen_, out_, outlen_, prng_, wprng_, LTC_ECCSIG_ANSIX962, NULL, key_)
+int ecc_sign_hash_rfc7518(const unsigned char *in,  unsigned long inlen,
+                          unsigned char *out, unsigned long *outlen,
+                          prng_state *prng, int wprng, const ecc_key *key);
+
+int ecc_sign_hash_rfc7518_ex(const unsigned char *in,  unsigned long inlen,
+                             unsigned char *out, unsigned long *outlen,
+                             prng_state *prng, int wprng,
+                             int *recid, const ecc_key *key);
+
+int ecc_sign_hash_rfc5656(const unsigned char *in,  unsigned long inlen,
+                          unsigned char *out, unsigned long *outlen,
+                          prng_state *prng, int wprng, const ecc_key *key);
+
+int ecc_sign_hash_eth27(const unsigned char *in,  unsigned long inlen,
+                        unsigned char *out, unsigned long *outlen,
+                        prng_state *prng, int wprng, const ecc_key *key);
 
 #define ecc_verify_hash_rfc7518(sig_, siglen_, hash_, hashlen_, stat_, key_) \
    ecc_verify_hash_ex(sig_, siglen_, hash_, hashlen_, LTC_ECCSIG_RFC7518, stat_, key_)
 
 #define ecc_verify_hash(sig_, siglen_, hash_, hashlen_, stat_, key_) \
    ecc_verify_hash_ex(sig_, siglen_, hash_, hashlen_, LTC_ECCSIG_ANSIX962, stat_, key_)
 
-int  ecc_sign_hash_ex(const unsigned char *in,  unsigned long inlen,
-                            unsigned char *out, unsigned long *outlen,
-                            prng_state *prng, int wprng, ecc_signature_type sigformat,
-                            int *recid, const ecc_key *key);
-
 int  ecc_verify_hash_ex(const unsigned char *sig,  unsigned long siglen,
                         const unsigned char *hash, unsigned long hashlen,
                         ecc_signature_type sigformat, int *stat, const ecc_key *key);

src/headers/tomcrypt_private.h

@@ -420,6 +420,10 @@ int ecc_import_pkcs8_asn1(ltc_asn1_list *alg_id, ltc_asn1_list *priv_key, ecc_ke
 int ecc_import_with_curve(const unsigned char *in, unsigned long inlen, int type, ecc_key *key);
 int ecc_import_with_oid(const unsigned char *in, unsigned long inlen, unsigned long *oid, unsigned long oid_len, int type, ecc_key *key);
 
+int ecc_sign_hash_internal(const unsigned char *in,  unsigned long inlen,
+                           void *r, void *s, prng_state *prng, int wprng,
+                           int *recid, const ecc_key *key);
+
 #ifdef LTC_SSH
 int ecc_ssh_ecdsa_encode_name(char *buffer, unsigned long *buflen, const ecc_key *key);
 #endif

src/pk/ecc/ecc_sign_hash.c

@@ -6,175 +6,36 @@
 #ifdef LTC_MECC
 
 /**
-  @file ecc_sign_hash.c
-  ECC Crypto, Tom St Denis
-*/
-
-/**
-  Sign a message digest
+  Sign a message digest (ANSI X9.62 format)
   @param in        The message digest to sign
   @param inlen     The length of the digest
   @param out       [out] The destination for the signature
   @param outlen    [in/out] The max size and resulting size of the signature
   @param prng      An active PRNG state
   @param wprng     The index of the PRNG you wish to use
-  @param sigformat The format of the signature to generate (ecc_signature_type)
-  @param recid     [out] The recovery ID for this signature (optional)
   @param key       A private ECC key
   @return CRYPT_OK if successful
 */
-int ecc_sign_hash_ex(const unsigned char *in,  unsigned long inlen,
-                     unsigned char *out, unsigned long *outlen,
-                     prng_state *prng, int wprng, ecc_signature_type sigformat,
-                     int *recid, const ecc_key *key)
+int ecc_sign_hash(const unsigned char *in,  unsigned long inlen,
+                  unsigned char *out, unsigned long *outlen,
+                  prng_state *prng, int wprng, const ecc_key *key)
 {
-   ecc_key       pubkey;
-   void          *r, *s, *e, *p, *b;
-   int           v = 0;
-   int           err, max_iterations = LTC_PK_MAX_RETRIES;
-   unsigned long pbits, pbytes, i, shift_right;
-   unsigned char ch, buf[MAXBLOCKSIZE];
+   int err;
+   void *r, *s;
 
-   LTC_ARGCHK(in     != NULL);
    LTC_ARGCHK(out    != NULL);
    LTC_ARGCHK(outlen != NULL);
-   LTC_ARGCHK(key    != NULL);
-
-   /* is this a private key? */
-   if (key->type != PK_PRIVATE) {
-      return CRYPT_PK_NOT_PRIVATE;
-   }
-
-   /* init the bignums */
-   if ((err = ltc_mp_init_multi(&r, &s, &e, &b, LTC_NULL)) != CRYPT_OK) {
-      return err;
-   }
-
-   /* get the hash and load it as a bignum into 'e' */
-   p = key->dp.order;
-   pbits = ltc_mp_count_bits(p);
-   pbytes = (pbits+7) >> 3;
-   if (pbits > inlen*8) {
-      if ((err = ltc_mp_read_unsigned_bin(e, in, inlen)) != CRYPT_OK)    { goto errnokey; }
-   }
-   else if (pbits % 8 == 0) {
-      if ((err = ltc_mp_read_unsigned_bin(e, in, pbytes)) != CRYPT_OK)   { goto errnokey; }
-   }
-   else {
-      shift_right = 8 - pbits % 8;
-      for (i=0, ch=0; i<pbytes; i++) {
-        buf[i] = ch;
-        ch = (in[i] << (8-shift_right));
-        buf[i] = buf[i] ^ (in[i] >> shift_right);
-      }
-      if ((err = ltc_mp_read_unsigned_bin(e, buf, pbytes)) != CRYPT_OK)  { goto errnokey; }
-   }
-
-   /* make up a key and export the public copy */
-   do {
-      if ((err = ecc_copy_curve(key, &pubkey)) != CRYPT_OK)                { goto errnokey; }
-      if ((err = ecc_generate_key(prng, wprng, &pubkey)) != CRYPT_OK)      { goto errnokey; }
 
-      /* find r = x1 mod n */
-      if ((err = ltc_mp_mod(pubkey.pubkey.x, p, r)) != CRYPT_OK)               { goto error; }
-
-      if (recid || sigformat==LTC_ECCSIG_ETH27) {
-         /* find recovery ID (if needed) */
-         v = 0;
-         if (ltc_mp_copy(pubkey.pubkey.x, s) != CRYPT_OK)                      { goto error; }
-         while (ltc_mp_cmp_d(s, 0) == LTC_MP_GT && ltc_mp_cmp(s, p) != LTC_MP_LT) {
-            /* Compute x1 div n... this will almost never be reached for curves with order 1 */
-            v += 2;
-            if ((err = ltc_mp_sub(s, p, s)) != CRYPT_OK)                       { goto error; }
-         }
-         if (ltc_mp_isodd(pubkey.pubkey.y)) v += 1;
-      }
-
-      if (ltc_mp_iszero(r) == LTC_MP_YES) {
-         ecc_free(&pubkey);
-      } else {
-         if ((err = rand_bn_upto(b, p, prng, wprng)) != CRYPT_OK)          { goto error; } /* b = blinding value */
-         /* find s = (e + xr)/k */
-         if ((err = ltc_mp_mulmod(pubkey.k, b, p, pubkey.k)) != CRYPT_OK)      { goto error; } /* k = kb */
-         if ((err = ltc_mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK)         { goto error; } /* k = 1/kb */
-         if ((err = ltc_mp_mulmod(key->k, r, p, s)) != CRYPT_OK)               { goto error; } /* s = xr */
-         if ((err = ltc_mp_mulmod(pubkey.k, s, p, s)) != CRYPT_OK)             { goto error; } /* s = xr/kb */
-         if ((err = ltc_mp_mulmod(pubkey.k, e, p, e)) != CRYPT_OK)             { goto error; } /* e = e/kb */
-         if ((err = ltc_mp_add(e, s, s)) != CRYPT_OK)                          { goto error; } /* s = e/kb + xr/kb */
-         if ((err = ltc_mp_mulmod(s, b, p, s)) != CRYPT_OK)                    { goto error; } /* s = b(e/kb + xr/kb) = (e + xr)/k */
-         ecc_free(&pubkey);
-         if (ltc_mp_iszero(s) == LTC_MP_NO) {
-            break;
-         }
-      }
-   } while (--max_iterations > 0);
-
-   if (max_iterations == 0) {
-      goto errnokey;
-   }
-
-   if (recid) *recid = v;
-
-   if (sigformat == LTC_ECCSIG_ANSIX962) {
-      /* store as ASN.1 SEQUENCE { r, s -- integer } */
-      err = der_encode_sequence_multi(out, outlen,
-                               LTC_ASN1_INTEGER, 1UL, r,
-                               LTC_ASN1_INTEGER, 1UL, s,
-                               LTC_ASN1_EOL, 0UL, NULL);
-   }
-   else if (sigformat == LTC_ECCSIG_RFC7518) {
-      /* RFC7518 format - raw (r,s) */
-      if (*outlen < 2*pbytes) { err = CRYPT_MEM; goto errnokey; }
-      zeromem(out, 2*pbytes);
-      i = ltc_mp_unsigned_bin_size(r);
-      if ((err = ltc_mp_to_unsigned_bin(r, out + (pbytes - i)))   != CRYPT_OK) { goto errnokey; }
-      i = ltc_mp_unsigned_bin_size(s);
-      if ((err = ltc_mp_to_unsigned_bin(s, out + (2*pbytes - i))) != CRYPT_OK) { goto errnokey; }
-      *outlen = 2*pbytes;
-      err = CRYPT_OK;
-   }
-   else if (sigformat == LTC_ECCSIG_ETH27) {
-      /* Ethereum (v,r,s) format */
-      if (pk_oid_cmp_with_ulong("1.3.132.0.10", key->dp.oid, key->dp.oidlen) != CRYPT_OK) {
-         /* Only valid for secp256k1 - OID 1.3.132.0.10 */
-         err = CRYPT_ERROR; goto errnokey;
-      }
-      if (*outlen < 65) { err = CRYPT_MEM; goto errnokey; }
-      zeromem(out, 65);
-      i = ltc_mp_unsigned_bin_size(r);
-      if ((err = ltc_mp_to_unsigned_bin(r, out + 32 - i)) != CRYPT_OK) { goto errnokey; }
-      i = ltc_mp_unsigned_bin_size(s);
-      if ((err = ltc_mp_to_unsigned_bin(s, out + 64 - i)) != CRYPT_OK) { goto errnokey; }
-      out[64] = (unsigned char)(v + 27); /* Recovery ID is 27/28 for Ethereum */
-      *outlen = 65;
-      err = CRYPT_OK;
-   }
-#ifdef LTC_SSH
-   else if (sigformat == LTC_ECCSIG_RFC5656) {
-      /* Get identifier string */
-      char name[64];
-      unsigned long namelen = sizeof(name);
-      if ((err = ecc_ssh_ecdsa_encode_name(name, &namelen, key)) != CRYPT_OK) { goto errnokey; }
-
-      /* Store as SSH data sequence, per RFC4251 */
-      err = ssh_encode_sequence_multi(out, outlen,
-                                      LTC_SSHDATA_STRING, name, namelen,
-                                      LTC_SSHDATA_MPINT,  r,
-                                      LTC_SSHDATA_MPINT,  s,
-                                      LTC_SSHDATA_EOL,    NULL);
-   }
-#endif
-   else {
-      /* Unknown signature format */
-      err = CRYPT_ERROR;
-      goto error;
-   }
+   if ((err = ltc_mp_init_multi(&r, &s, LTC_NULL)) != CRYPT_OK) return err;
+   if ((err = ecc_sign_hash_internal(in, inlen, r, s, prng, wprng, NULL, key)) != CRYPT_OK) goto error;
 
-   goto errnokey;
+   /* store as ASN.1 SEQUENCE { r, s -- integer } */
+   err = der_encode_sequence_multi(out, outlen,
+                                   LTC_ASN1_INTEGER, 1UL, r,
+                                   LTC_ASN1_INTEGER, 1UL, s,
+                                   LTC_ASN1_EOL, 0UL, NULL);
 error:
-   ecc_free(&pubkey);
-errnokey:
-   ltc_mp_deinit_multi(r, s, e, b, LTC_NULL);
+   ltc_mp_deinit_multi(r, s, LTC_NULL);
    return err;
 }
 

src/pk/ecc/ecc_sign_hash_eth27.c

@@ -0,0 +1,57 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+#include "tomcrypt_private.h"
+
+#ifdef LTC_MECC
+
+/**
+  Sign a message digest (Ethereum format with recovery_id+27)
+  @param in        The message digest to sign
+  @param inlen     The length of the digest
+  @param out       [out] The destination for the signature
+  @param outlen    [in/out] The max size and resulting size of the signature
+  @param prng      An active PRNG state
+  @param wprng     The index of the PRNG you wish to use
+  @param key       A private ECC key
+  @return CRYPT_OK if successful
+*/
+int ecc_sign_hash_eth27(const unsigned char *in,  unsigned long inlen,
+                        unsigned char *out, unsigned long *outlen,
+                        prng_state *prng, int wprng, const ecc_key *key)
+{
+   int err, recid;
+   void *r, *s;
+   unsigned long i;
+
+   LTC_ARGCHK(out    != NULL);
+   LTC_ARGCHK(outlen != NULL);
+   LTC_ARGCHK(key    != NULL);
+
+   /* Only valid for secp256k1 - OID 1.3.132.0.10 */
+   if (pk_oid_cmp_with_ulong("1.3.132.0.10", key->dp.oid, key->dp.oidlen) != CRYPT_OK) {
+      return CRYPT_ERROR;
+   }
+   if (*outlen < 65) {
+      *outlen = 65;
+      return CRYPT_BUFFER_OVERFLOW;
+   }
+
+   if ((err = ltc_mp_init_multi(&r, &s, LTC_NULL)) != CRYPT_OK) return err;
+   if ((err = ecc_sign_hash_internal(in, inlen, r, s, prng, wprng, &recid, key)) != CRYPT_OK) goto error;
+
+   zeromem(out, 65);
+   *outlen = 65;
+   i = ltc_mp_unsigned_bin_size(r);
+   if ((err = ltc_mp_to_unsigned_bin(r, out + 32 - i)) != CRYPT_OK) goto error;
+   i = ltc_mp_unsigned_bin_size(s);
+   if ((err = ltc_mp_to_unsigned_bin(s, out + 64 - i)) != CRYPT_OK) goto error;
+   out[64] = (unsigned char)(recid + 27); /* Recovery ID is 27/28 for Ethereum */
+   err = CRYPT_OK;
+
+error:
+   ltc_mp_deinit_multi(r, s, LTC_NULL);
+   return err;
+}
+
+#endif