add a test-decipher command

test-decipher will for rsa do public encrypt on a random string and let
the key decrypt
for ec it will generate a new ec key and do ecdh and confirm it gets the
same answer back

lib/ykpiv.c

@@ -498,11 +498,10 @@ ykpiv_rc ykpiv_hex_decode(const char *hex_in, size_t in_len,
   return YKPIV_OK;
 }
 
-ykpiv_rc ykpiv_sign_data(ykpiv_state *state,
+static ykpiv_rc _general_authenticate(ykpiv_state *state,
     const unsigned char *raw_in, size_t in_len,
-    unsigned char *sign_out, size_t *out_len,
+    unsigned char *out, size_t *out_len,
-    unsigned char algorithm, unsigned char key) {
+    unsigned char algorithm, unsigned char key, bool decipher) {
-
   unsigned char indata[1024];
   unsigned char *dataptr = indata;
   unsigned char data[1024];
@@ -522,14 +521,23 @@ ykpiv_rc ykpiv_sign_data(ykpiv_state *state,
       if(pad_len == 0) {
 	pad_len = 256;
       }
-      if(in_len + RSA_PKCS1_PADDING_SIZE > pad_len) {
+      if(!decipher) {
-	return YKPIV_SIZE_ERROR;
+	if(in_len + RSA_PKCS1_PADDING_SIZE > pad_len) {
+	  return YKPIV_SIZE_ERROR;
+	}
+	RSA_padding_add_PKCS1_type_1(sign_in, pad_len, raw_in, in_len);
+	in_len = pad_len;
+      } else {
+	if(in_len != pad_len) {
+	  return YKPIV_SIZE_ERROR;
+	}
+	memcpy(sign_in, raw_in, in_len);
       }
-      RSA_padding_add_PKCS1_type_1(sign_in, pad_len, raw_in, in_len);
-      in_len = pad_len;
       break;
     case YKPIV_ALGO_ECCP256:
-      if(in_len > 32) {
+      if(!decipher && in_len > 32) {
+	return YKPIV_SIZE_ERROR;
+      } else if(decipher && in_len != 65) {
 	return YKPIV_SIZE_ERROR;
       }
       memcpy(sign_in, raw_in, in_len);
@@ -550,7 +558,7 @@ ykpiv_rc ykpiv_sign_data(ykpiv_state *state,
   dataptr += set_length(dataptr, in_len + bytes + 3);
   *dataptr++ = 0x82;
   *dataptr++ = 0x00;
-  *dataptr++ = 0x81;
+  *dataptr++ = algorithm == YKPIV_ALGO_ECCP256 && decipher ? 0x85 : 0x81;
   dataptr += set_length(dataptr, in_len);
   memcpy(dataptr, sign_in, (size_t)in_len);
   dataptr += in_len;
@@ -592,10 +600,27 @@ ykpiv_rc ykpiv_sign_data(ykpiv_state *state,
     return YKPIV_SIZE_ERROR;
   }
   *out_len = len;
-  memcpy(sign_out, dataptr, len);
+  memcpy(out, dataptr, len);
   return YKPIV_OK;
 }
 
+ykpiv_rc ykpiv_sign_data(ykpiv_state *state,
+    const unsigned char *raw_in, size_t in_len,
+    unsigned char *sign_out, size_t *out_len,
+    unsigned char algorithm, unsigned char key) {
+
+  return _general_authenticate(state, raw_in, in_len, sign_out, out_len,
+      algorithm, key, false);
+}
+
+
+ykpiv_rc ykpiv_decipher_data(ykpiv_state *state, const unsigned char *in,
+    size_t in_len, unsigned char *out, size_t *out_len,
+    unsigned char algorithm, unsigned char key) {
+  return _general_authenticate(state, in, in_len, out, out_len,
+      algorithm, key, true);
+}
+
 ykpiv_rc ykpiv_get_version(ykpiv_state *state, char *version, size_t len) {
   APDU apdu;
   unsigned char data[0xff];

lib/ykpiv.h

@@ -75,6 +75,9 @@ extern "C"
 	ykpiv_rc ykpiv_sign_data(ykpiv_state *state, const unsigned char *sign_in,
 			size_t in_len,unsigned char *sign_out, size_t *out_len,
 			unsigned char algorithm, unsigned char key);
+        ykpiv_rc ykpiv_decipher_data(ykpiv_state *state, const unsigned char *enc_in,
+                        size_t in_len, unsigned char *enc_out, size_t *out_len,
+                        unsigned char algorithm, unsigned char key);
 	ykpiv_rc ykpiv_get_version(ykpiv_state *state, char *version, size_t len);
 	ykpiv_rc ykpiv_verify(ykpiv_state *state, const char *pin, int *tries);
 	ykpiv_rc ykpiv_fetch_object(ykpiv_state *state, int object_id,

lib/ykpiv.map

@@ -47,3 +47,9 @@ global:
 local:
 	*;
 };
+
+YKPIV_0.2.0
+{
+global:
+	ykpiv_decipher_data;
+} YKPIV_0.1.0;

tool/cmdline.ggo

@@ -31,7 +31,7 @@ option "action" a "Action to take" values="version","generate","set-mgm-key",
        "reset","pin-retries","import-key","import-certificate","set-chuid",
        "request-certificate","verify-pin","change-pin","change-puk","unblock-pin",
        "selfsign-certificate","delete-certificate","read-certificate","status",
-       "test-signature" enum multiple
+       "test-signature","test-decipher" enum multiple
 text   "
        Multiple actions may be given at once and will be executed in order
        for example --action=verify-pin --action=request-certificate\n"

tool/yubico-piv-tool.c

@@ -1484,6 +1484,137 @@ test_out:
   return ret;
 }
 
+static bool test_decipher(ykpiv_state *state, enum enum_slot slot,
+    const char *input_file_name, enum enum_key_format cert_format, int verbose) {
+  bool ret = false;
+  X509 *x509 = NULL;
+  EVP_PKEY *pubkey;
+  EC_KEY *tmpkey = NULL;
+  FILE *input_file = open_file(input_file_name, INPUT);
+
+  if(!input_file) {
+    fprintf(stderr, "Failed opening input file %s.\n", input_file_name);
+    return false;
+  }
+
+  if(isatty(fileno(input_file))) {
+    fprintf(stderr, "Please paste the certificate to encrypt for...\n");
+  }
+
+  if(cert_format == key_format_arg_PEM) {
+    x509 = PEM_read_X509(input_file, NULL, NULL, NULL);
+  } else if(cert_format == key_format_arg_DER) {
+    x509 = d2i_X509_fp(input_file, NULL);
+  } else {
+    fprintf(stderr, "Only PEM or DER format is supported for test-decipher.\n");
+    goto decipher_out;
+  }
+  if(!x509) {
+    fprintf(stderr, "Failed loading certificate for test-decipher.\n");
+    goto decipher_out;
+  }
+
+  {
+    int key = 0;
+    unsigned char algorithm;
+
+    pubkey = X509_get_pubkey(x509);
+    if(!pubkey) {
+      fprintf(stderr, "Parse error.\n");
+      goto decipher_out;
+    }
+    algorithm = get_algorithm(pubkey);
+    if(algorithm == 0) {
+      goto decipher_out;
+    }
+    sscanf(cmdline_parser_slot_values[slot], "%2x", &key);
+    if(algorithm == YKPIV_ALGO_RSA1024 || algorithm == YKPIV_ALGO_RSA2048) {
+      unsigned char secret[32];
+      unsigned char secret2[32];
+      unsigned char data[256];
+      int len;
+      size_t len2 = sizeof(data);
+      RSA *rsa = EVP_PKEY_get1_RSA(pubkey);
+
+      if(RAND_pseudo_bytes(secret, sizeof(secret)) == -1) {
+        fprintf(stderr, "error: no randomness.\n");
+        ret = false;
+        goto decipher_out;
+      }
+
+      RSA_padding_add_PKCS1_type_1(data, RSA_size(rsa), secret, sizeof(secret));
+      len = RSA_public_encrypt(RSA_size(rsa), data, data, rsa, RSA_NO_PADDING);
+      if(len < 0) {
+        fprintf(stderr, "Failed performing RSA encryption!\n");
+        goto decipher_out;
+      }
+      if(ykpiv_decipher_data(state, data, (size_t)len, data, &len2, algorithm, key) != YKPIV_OK) {
+        fprintf(stderr, "RSA decrypt failed!\n");
+        goto decipher_out;
+      }
+      /* for some reason we have to give the padding check function data + 1 */
+      len = RSA_padding_check_PKCS1_type_1(secret2, sizeof(secret2), data + 1, len2 - 1, RSA_size(rsa));
+      if(len == sizeof(secret)) {
+        if(verbose) {
+          fprintf(stderr, "Generated nonce: ");
+          dump_hex(secret, sizeof(secret), stderr, true);
+          fprintf(stderr, "Decrypted nonce: ");
+          dump_hex(secret2, sizeof(secret2), stderr, true);
+        }
+        if(memcmp(secret, secret2, sizeof(secret)) == 0) {
+          fprintf(stderr, "Successfully performed RSA decryption!\n");
+          ret = true;
+        } else {
+          fprintf(stderr, "Failed performing RSA decryption!\n");
+        }
+      } else {
+        fprintf(stderr, "Failed unwrapping PKCS1 envelope.\n");
+      }
+    } else {
+      unsigned char secret[32];
+      unsigned char secret2[32];
+      unsigned char public_key[65];
+      unsigned char *ptr = public_key;
+      size_t len = sizeof(secret);
+      EC_KEY *ec = EVP_PKEY_get1_EC_KEY(pubkey);
+
+      tmpkey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
+      EC_KEY_generate_key(tmpkey);
+      ECDH_compute_key(secret, len, EC_KEY_get0_public_key(ec), tmpkey, NULL);
+
+      i2o_ECPublicKey(tmpkey, &ptr);
+      if(ykpiv_decipher_data(state, public_key, sizeof(public_key), secret2, &len, algorithm, key) != YKPIV_OK) {
+        fprintf(stderr, "Failed ECDH exchange!\n");
+        goto decipher_out;
+      }
+      if(verbose) {
+        fprintf(stderr, "ECDH host generated: ");
+        dump_hex(secret, len, stderr, true);
+        fprintf(stderr, "ECDH card generated: ");
+        dump_hex(secret2, len, stderr, true);
+      }
+      if(memcmp(secret, secret2, 32) == 0) {
+        fprintf(stderr, "Successfully performed ECDH exchange with card.\n");
+        ret = true;
+      } else {
+        fprintf(stderr, "ECDH exchange with card failed!\n");
+      }
+    }
+  }
+
+decipher_out:
+  if(tmpkey) {
+    EC_KEY_free(tmpkey);
+  }
+  if(x509) {
+    X509_free(x509);
+  }
+  if(input_file != stdin) {
+    fclose(input_file);
+  }
+  return ret;
+}
+
 int main(int argc, char *argv[]) {
   struct gengetopt_args_info args_info;
   ykpiv_state *state;
@@ -1514,6 +1645,7 @@ int main(int argc, char *argv[]) {
       case action_arg_deleteMINUS_certificate:
       case action_arg_readMINUS_certificate:
       case action_arg_testMINUS_signature:
+      case action_arg_testMINUS_decipher:
         if(args_info.slot_arg == slot__NULL) {
           fprintf(stderr, "The '%s' action needs a slot (-s) to operate on.\n",
               cmdline_parser_action_values[action]);
@@ -1596,6 +1728,7 @@ int main(int argc, char *argv[]) {
       case action_arg_readMINUS_certificate:
       case action_arg_status:
       case action_arg_testMINUS_signature:
+      case action_arg_testMINUS_decipher:
       case action__NULL:
       default:
         if(verbosity) {
@@ -1758,6 +1891,12 @@ int main(int argc, char *argv[]) {
           ret = EXIT_FAILURE;
         }
         break;
+      case action_arg_testMINUS_decipher:
+        if(test_decipher(state, args_info.slot_arg, args_info.input_arg,
+              args_info.key_format_arg, verbosity) == false) {
+          ret = EXIT_FAILURE;
+        }
+        break;
       case action__NULL:
       default:
         fprintf(stderr, "Wrong action. %d.\n", action);