doc/man3/PEM_read_bio_PrivateKey.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 pem_password_cb,
   6 PEM_read_bio_PrivateKey, PEM_read_PrivateKey, PEM_write_bio_PrivateKey,
   7 PEM_write_bio_PrivateKey_traditional, PEM_write_PrivateKey,
   8 PEM_write_bio_PKCS8PrivateKey, PEM_write_PKCS8PrivateKey,
   9 PEM_write_bio_PKCS8PrivateKey_nid, PEM_write_PKCS8PrivateKey_nid,
  10 PEM_read_bio_PUBKEY, PEM_read_PUBKEY, PEM_write_bio_PUBKEY, PEM_write_PUBKEY,
  11 PEM_read_bio_RSAPrivateKey, PEM_read_RSAPrivateKey,
  12 PEM_write_bio_RSAPrivateKey, PEM_write_RSAPrivateKey,
  13 PEM_read_bio_RSAPublicKey, PEM_read_RSAPublicKey, PEM_write_bio_RSAPublicKey,
  14 PEM_write_RSAPublicKey, PEM_read_bio_RSA_PUBKEY, PEM_read_RSA_PUBKEY,
  15 PEM_write_bio_RSA_PUBKEY, PEM_write_RSA_PUBKEY, PEM_read_bio_DSAPrivateKey,
  16 PEM_read_DSAPrivateKey, PEM_write_bio_DSAPrivateKey, PEM_write_DSAPrivateKey,
  17 PEM_read_bio_DSA_PUBKEY, PEM_read_DSA_PUBKEY, PEM_write_bio_DSA_PUBKEY,
  18 PEM_write_DSA_PUBKEY, PEM_read_bio_Parameters, PEM_write_bio_Parameters,
  19 PEM_read_bio_DSAparams, PEM_read_DSAparams,
  20 PEM_write_bio_DSAparams, PEM_write_DSAparams, PEM_read_bio_DHparams,
  21 PEM_read_DHparams, PEM_write_bio_DHparams, PEM_write_DHparams,
  22 PEM_read_bio_X509, PEM_read_X509, PEM_write_bio_X509, PEM_write_X509,
  23 PEM_read_bio_X509_AUX, PEM_read_X509_AUX, PEM_write_bio_X509_AUX,
  24 PEM_write_X509_AUX, PEM_read_bio_X509_REQ, PEM_read_X509_REQ,
  25 PEM_write_bio_X509_REQ, PEM_write_X509_REQ, PEM_write_bio_X509_REQ_NEW,
  26 PEM_write_X509_REQ_NEW, PEM_read_bio_X509_CRL, PEM_read_X509_CRL,
  27 PEM_write_bio_X509_CRL, PEM_write_X509_CRL, PEM_read_bio_PKCS7, PEM_read_PKCS7,
  28 PEM_write_bio_PKCS7, PEM_write_PKCS7 - PEM routines
  29
  30 =head1 SYNOPSIS
  31
  32  #include <openssl/pem.h>
  33
  34  typedef int pem_password_cb(char *buf, int size, int rwflag, void *u);
  35
  36  EVP_PKEY *PEM_read_bio_PrivateKey(BIO *bp, EVP_PKEY **x,
  37                                    pem_password_cb *cb, void *u);
  38  EVP_PKEY *PEM_read_PrivateKey(FILE *fp, EVP_PKEY **x,
  39                                pem_password_cb *cb, void *u);
  40  int PEM_write_bio_PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
  41                               unsigned char *kstr, int klen,
  42                               pem_password_cb *cb, void *u);
  43  int PEM_write_bio_PrivateKey_traditional(BIO *bp, EVP_PKEY *x,
  44                                           const EVP_CIPHER *enc,
  45                                           unsigned char *kstr, int klen,
  46                                           pem_password_cb *cb, void *u);
  47  int PEM_write_PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
  48                           unsigned char *kstr, int klen,
  49                           pem_password_cb *cb, void *u);
  50
  51  int PEM_write_bio_PKCS8PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
  52                                    char *kstr, int klen,
  53                                    pem_password_cb *cb, void *u);
  54  int PEM_write_PKCS8PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
  55                                char *kstr, int klen,
  56                                pem_password_cb *cb, void *u);
  57  int PEM_write_bio_PKCS8PrivateKey_nid(BIO *bp, EVP_PKEY *x, int nid,
  58                                        char *kstr, int klen,
  59                                        pem_password_cb *cb, void *u);
  60  int PEM_write_PKCS8PrivateKey_nid(FILE *fp, EVP_PKEY *x, int nid,
  61                                    char *kstr, int klen,
  62                                    pem_password_cb *cb, void *u);
  63
  64  EVP_PKEY *PEM_read_bio_PUBKEY(BIO *bp, EVP_PKEY **x,
  65                                pem_password_cb *cb, void *u);
  66  EVP_PKEY *PEM_read_PUBKEY(FILE *fp, EVP_PKEY **x,
  67                            pem_password_cb *cb, void *u);
  68  int PEM_write_bio_PUBKEY(BIO *bp, EVP_PKEY *x);
  69  int PEM_write_PUBKEY(FILE *fp, EVP_PKEY *x);
  70
  71  RSA *PEM_read_bio_RSAPrivateKey(BIO *bp, RSA **x,
  72                                  pem_password_cb *cb, void *u);
  73  RSA *PEM_read_RSAPrivateKey(FILE *fp, RSA **x,
  74                              pem_password_cb *cb, void *u);
  75  int PEM_write_bio_RSAPrivateKey(BIO *bp, RSA *x, const EVP_CIPHER *enc,
  76                                  unsigned char *kstr, int klen,
  77                                  pem_password_cb *cb, void *u);
  78  int PEM_write_RSAPrivateKey(FILE *fp, RSA *x, const EVP_CIPHER *enc,
  79                              unsigned char *kstr, int klen,
  80                              pem_password_cb *cb, void *u);
  81
  82  RSA *PEM_read_bio_RSAPublicKey(BIO *bp, RSA **x,
  83                                 pem_password_cb *cb, void *u);
  84  RSA *PEM_read_RSAPublicKey(FILE *fp, RSA **x,
  85                             pem_password_cb *cb, void *u);
  86  int PEM_write_bio_RSAPublicKey(BIO *bp, RSA *x);
  87  int PEM_write_RSAPublicKey(FILE *fp, RSA *x);
  88
  89  RSA *PEM_read_bio_RSA_PUBKEY(BIO *bp, RSA **x,
  90                               pem_password_cb *cb, void *u);
  91  RSA *PEM_read_RSA_PUBKEY(FILE *fp, RSA **x,
  92                           pem_password_cb *cb, void *u);
  93  int PEM_write_bio_RSA_PUBKEY(BIO *bp, RSA *x);
  94  int PEM_write_RSA_PUBKEY(FILE *fp, RSA *x);
  95
  96  DSA *PEM_read_bio_DSAPrivateKey(BIO *bp, DSA **x,
  97                                  pem_password_cb *cb, void *u);
  98  DSA *PEM_read_DSAPrivateKey(FILE *fp, DSA **x,
  99                              pem_password_cb *cb, void *u);
 100  int PEM_write_bio_DSAPrivateKey(BIO *bp, DSA *x, const EVP_CIPHER *enc,
 101                                  unsigned char *kstr, int klen,
 102                                  pem_password_cb *cb, void *u);
 103  int PEM_write_DSAPrivateKey(FILE *fp, DSA *x, const EVP_CIPHER *enc,
 104                              unsigned char *kstr, int klen,
 105                              pem_password_cb *cb, void *u);
 106
 107  DSA *PEM_read_bio_DSA_PUBKEY(BIO *bp, DSA **x,
 108                               pem_password_cb *cb, void *u);
 109  DSA *PEM_read_DSA_PUBKEY(FILE *fp, DSA **x,
 110                           pem_password_cb *cb, void *u);
 111  int PEM_write_bio_DSA_PUBKEY(BIO *bp, DSA *x);
 112  int PEM_write_DSA_PUBKEY(FILE *fp, DSA *x);
 113
 114  EVP_PKEY *PEM_read_bio_Parameters(BIO *bp, EVP_PKEY **x);
 115  int PEM_write_bio_Parameters(BIO *bp, const EVP_PKEY *x);
 116
 117  DSA *PEM_read_bio_DSAparams(BIO *bp, DSA **x, pem_password_cb *cb, void *u);
 118  DSA *PEM_read_DSAparams(FILE *fp, DSA **x, pem_password_cb *cb, void *u);
 119  int PEM_write_bio_DSAparams(BIO *bp, DSA *x);
 120  int PEM_write_DSAparams(FILE *fp, DSA *x);
 121
 122  DH *PEM_read_bio_DHparams(BIO *bp, DH **x, pem_password_cb *cb, void *u);
 123  DH *PEM_read_DHparams(FILE *fp, DH **x, pem_password_cb *cb, void *u);
 124  int PEM_write_bio_DHparams(BIO *bp, DH *x);
 125  int PEM_write_DHparams(FILE *fp, DH *x);
 126
 127  X509 *PEM_read_bio_X509(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
 128  X509 *PEM_read_X509(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
 129  int PEM_write_bio_X509(BIO *bp, X509 *x);
 130  int PEM_write_X509(FILE *fp, X509 *x);
 131
 132  X509 *PEM_read_bio_X509_AUX(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
 133  X509 *PEM_read_X509_AUX(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
 134  int PEM_write_bio_X509_AUX(BIO *bp, X509 *x);
 135  int PEM_write_X509_AUX(FILE *fp, X509 *x);
 136
 137  X509_REQ *PEM_read_bio_X509_REQ(BIO *bp, X509_REQ **x,
 138                                  pem_password_cb *cb, void *u);
 139  X509_REQ *PEM_read_X509_REQ(FILE *fp, X509_REQ **x,
 140                              pem_password_cb *cb, void *u);
 141  int PEM_write_bio_X509_REQ(BIO *bp, X509_REQ *x);
 142  int PEM_write_X509_REQ(FILE *fp, X509_REQ *x);
 143  int PEM_write_bio_X509_REQ_NEW(BIO *bp, X509_REQ *x);
 144  int PEM_write_X509_REQ_NEW(FILE *fp, X509_REQ *x);
 145
 146  X509_CRL *PEM_read_bio_X509_CRL(BIO *bp, X509_CRL **x,
 147                                  pem_password_cb *cb, void *u);
 148  X509_CRL *PEM_read_X509_CRL(FILE *fp, X509_CRL **x,
 149                              pem_password_cb *cb, void *u);
 150  int PEM_write_bio_X509_CRL(BIO *bp, X509_CRL *x);
 151  int PEM_write_X509_CRL(FILE *fp, X509_CRL *x);
 152
 153  PKCS7 *PEM_read_bio_PKCS7(BIO *bp, PKCS7 **x, pem_password_cb *cb, void *u);
 154  PKCS7 *PEM_read_PKCS7(FILE *fp, PKCS7 **x, pem_password_cb *cb, void *u);
 155  int PEM_write_bio_PKCS7(BIO *bp, PKCS7 *x);
 156  int PEM_write_PKCS7(FILE *fp, PKCS7 *x);
 157
 158 =head1 DESCRIPTION
 159
 160 The PEM functions read or write structures in PEM format. In
 161 this sense PEM format is simply base64 encoded data surrounded
 162 by header lines.
 163
 164 For more details about the meaning of arguments see the
 165 B<PEM FUNCTION ARGUMENTS> section.
 166
 167 Each operation has four functions associated with it. For
 168 brevity the term "B<TYPE> functions" will be used below to collectively
 169 refer to the PEM_read_bio_TYPE(), PEM_read_TYPE(),
 170 PEM_write_bio_TYPE(), and PEM_write_TYPE() functions.
 171
 172 The B<PrivateKey> functions read or write a private key in PEM format using an
 173 EVP_PKEY structure. The write routines use PKCS#8 private key format and are
 174 equivalent to PEM_write_bio_PKCS8PrivateKey().The read functions transparently
 175 handle traditional and PKCS#8 format encrypted and unencrypted keys.
 176
 177 PEM_write_bio_PrivateKey_traditional() writes out a private key in the
 178 "traditional" format with a simple private key marker and should only
 179 be used for compatibility with legacy programs.
 180
 181 PEM_write_bio_PKCS8PrivateKey() and PEM_write_PKCS8PrivateKey() write a private
 182 key in an EVP_PKEY structure in PKCS#8 EncryptedPrivateKeyInfo format using
 183 PKCS#5 v2.0 password based encryption algorithms. The B<cipher> argument
 184 specifies the encryption algorithm to use: unlike some other PEM routines the
 185 encryption is applied at the PKCS#8 level and not in the PEM headers. If
 186 B<cipher> is NULL then no encryption is used and a PKCS#8 PrivateKeyInfo
 187 structure is used instead.
 188
 189 PEM_write_bio_PKCS8PrivateKey_nid() and PEM_write_PKCS8PrivateKey_nid()
 190 also write out a private key as a PKCS#8 EncryptedPrivateKeyInfo however
 191 it uses PKCS#5 v1.5 or PKCS#12 encryption algorithms instead. The algorithm
 192 to use is specified in the B<nid> parameter and should be the NID of the
 193 corresponding OBJECT IDENTIFIER (see NOTES section).
 194
 195 The B<PUBKEY> functions process a public key using an EVP_PKEY
 196 structure. The public key is encoded as a SubjectPublicKeyInfo
 197 structure.
 198
 199 The B<RSAPrivateKey> functions process an RSA private key using an
 200 RSA structure. The write routines uses traditional format. The read
 201 routines handles the same formats as the B<PrivateKey>
 202 functions but an error occurs if the private key is not RSA.
 203
 204 The B<RSAPublicKey> functions process an RSA public key using an
 205 RSA structure. The public key is encoded using a PKCS#1 RSAPublicKey
 206 structure.
 207
 208 The B<RSA_PUBKEY> functions also process an RSA public key using
 209 an RSA structure. However the public key is encoded using a
 210 SubjectPublicKeyInfo structure and an error occurs if the public
 211 key is not RSA.
 212
 213 The B<DSAPrivateKey> functions process a DSA private key using a
 214 DSA structure. The write routines uses traditional format. The read
 215 routines handles the same formats as the B<PrivateKey>
 216 functions but an error occurs if the private key is not DSA.
 217
 218 The B<DSA_PUBKEY> functions process a DSA public key using
 219 a DSA structure. The public key is encoded using a
 220 SubjectPublicKeyInfo structure and an error occurs if the public
 221 key is not DSA.
 222
 223 The B<Parameters> functions read or write key parameters in PEM format using
 224 an EVP_PKEY structure.  The encoding depends on the type of key; for DSA key
 225 parameters, it will be a Dss-Parms structure as defined in RFC2459, and for DH
 226 key parameters, it will be a PKCS#3 DHparameter structure.  I<These functions
 227 only exist for the B<BIO> type>.
 228
 229 The B<DSAparams> functions process DSA parameters using a DSA
 230 structure. The parameters are encoded using a Dss-Parms structure
 231 as defined in RFC2459.
 232
 233 The B<DHparams> functions process DH parameters using a DH
 234 structure. The parameters are encoded using a PKCS#3 DHparameter
 235 structure.
 236
 237 The B<X509> functions process an X509 certificate using an X509
 238 structure. They will also process a trusted X509 certificate but
 239 any trust settings are discarded.
 240
 241 The B<X509_AUX> functions process a trusted X509 certificate using
 242 an X509 structure.
 243
 244 The B<X509_REQ> and B<X509_REQ_NEW> functions process a PKCS#10
 245 certificate request using an X509_REQ structure. The B<X509_REQ>
 246 write functions use B<CERTIFICATE REQUEST> in the header whereas
 247 the B<X509_REQ_NEW> functions use B<NEW CERTIFICATE REQUEST>
 248 (as required by some CAs). The B<X509_REQ> read functions will
 249 handle either form so there are no B<X509_REQ_NEW> read functions.
 250
 251 The B<X509_CRL> functions process an X509 CRL using an X509_CRL
 252 structure.
 253
 254 The B<PKCS7> functions process a PKCS#7 ContentInfo using a PKCS7
 255 structure.
 256
 257 =head1 PEM FUNCTION ARGUMENTS
 258
 259 The PEM functions have many common arguments.
 260
 261 The B<bp> BIO parameter (if present) specifies the BIO to read from
 262 or write to.
 263
 264 The B<fp> FILE parameter (if present) specifies the FILE pointer to
 265 read from or write to.
 266
 267 The PEM read functions all take an argument B<TYPE **x> and return
 268 a B<TYPE *> pointer. Where B<TYPE> is whatever structure the function
 269 uses. If B<x> is NULL then the parameter is ignored. If B<x> is not
 270 NULL but B<*x> is NULL then the structure returned will be written
 271 to B<*x>. If neither B<x> nor B<*x> is NULL then an attempt is made
 272 to reuse the structure at B<*x> (but see BUGS and EXAMPLES sections).
 273 Irrespective of the value of B<x> a pointer to the structure is always
 274 returned (or NULL if an error occurred).
 275
 276 The PEM functions which write private keys take an B<enc> parameter
 277 which specifies the encryption algorithm to use, encryption is done
 278 at the PEM level. If this parameter is set to NULL then the private
 279 key is written in unencrypted form.
 280
 281 The B<cb> argument is the callback to use when querying for the pass
 282 phrase used for encrypted PEM structures (normally only private keys).
 283
 284 For the PEM write routines if the B<kstr> parameter is not NULL then
 285 B<klen> bytes at B<kstr> are used as the passphrase and B<cb> is
 286 ignored.
 287
 288 If the B<cb> parameters is set to NULL and the B<u> parameter is not
 289 NULL then the B<u> parameter is interpreted as a null terminated string
 290 to use as the passphrase. If both B<cb> and B<u> are NULL then the
 291 default callback routine is used which will typically prompt for the
 292 passphrase on the current terminal with echoing turned off.
 293
 294 The default passphrase callback is sometimes inappropriate (for example
 295 in a GUI application) so an alternative can be supplied. The callback
 296 routine has the following form:
 297
 298  int cb(char *buf, int size, int rwflag, void *u);
 299
 300 B<buf> is the buffer to write the passphrase to. B<size> is the maximum
 301 length of the passphrase (i.e. the size of buf). B<rwflag> is a flag
 302 which is set to 0 when reading and 1 when writing. A typical routine
 303 will ask the user to verify the passphrase (for example by prompting
 304 for it twice) if B<rwflag> is 1. The B<u> parameter has the same
 305 value as the B<u> parameter passed to the PEM routine. It allows
 306 arbitrary data to be passed to the callback by the application
 307 (for example a window handle in a GUI application). The callback
 308 B<must> return the number of characters in the passphrase or -1 if
 309 an error occurred.
 310
 311 =head1 NOTES
 312
 313 The old B<PrivateKey> write routines are retained for compatibility.
 314 New applications should write private keys using the
 315 PEM_write_bio_PKCS8PrivateKey() or PEM_write_PKCS8PrivateKey() routines
 316 because they are more secure (they use an iteration count of 2048 whereas
 317 the traditional routines use a count of 1) unless compatibility with older
 318 versions of OpenSSL is important.
 319
 320 The B<PrivateKey> read routines can be used in all applications because
 321 they handle all formats transparently.
 322
 323 A frequent cause of problems is attempting to use the PEM routines like
 324 this:
 325
 326  X509 *x;
 327
 328  PEM_read_bio_X509(bp, &x, 0, NULL);
 329
 330 this is a bug because an attempt will be made to reuse the data at B<x>
 331 which is an uninitialised pointer.
 332
 333 These functions make no assumption regarding the pass phrase received from the
 334 password callback.
 335 It will simply be treated as a byte sequence.
 336
 337 =head1 PEM ENCRYPTION FORMAT
 338
 339 These old B<PrivateKey> routines use a non standard technique for encryption.
 340
 341 The private key (or other data) takes the following form:
 342
 343  -----BEGIN RSA PRIVATE KEY-----
 344  Proc-Type: 4,ENCRYPTED
 345  DEK-Info: DES-EDE3-CBC,3F17F5316E2BAC89
 346
 347  ...base64 encoded data...
 348  -----END RSA PRIVATE KEY-----
 349
 350 The line beginning with I<Proc-Type> contains the version and the
 351 protection on the encapsulated data. The line beginning I<DEK-Info>
 352 contains two comma separated values: the encryption algorithm name as
 353 used by EVP_get_cipherbyname() and an initialization vector used by the
 354 cipher encoded as a set of hexadecimal digits. After those two lines is
 355 the base64-encoded encrypted data.
 356
 357 The encryption key is derived using EVP_BytesToKey(). The cipher's
 358 initialization vector is passed to EVP_BytesToKey() as the B<salt>
 359 parameter. Internally, B<PKCS5_SALT_LEN> bytes of the salt are used
 360 (regardless of the size of the initialization vector). The user's
 361 password is passed to EVP_BytesToKey() using the B<data> and B<datal>
 362 parameters. Finally, the library uses an iteration count of 1 for
 363 EVP_BytesToKey().
 364
 365 The B<key> derived by EVP_BytesToKey() along with the original initialization
 366 vector is then used to decrypt the encrypted data. The B<iv> produced by
 367 EVP_BytesToKey() is not utilized or needed, and NULL should be passed to
 368 the function.
 369
 370 The pseudo code to derive the key would look similar to:
 371
 372  EVP_CIPHER* cipher = EVP_des_ede3_cbc();
 373  EVP_MD* md = EVP_md5();
 374
 375  unsigned int nkey = EVP_CIPHER_key_length(cipher);
 376  unsigned int niv = EVP_CIPHER_iv_length(cipher);
 377  unsigned char key[nkey];
 378  unsigned char iv[niv];
 379
 380  memcpy(iv, HexToBin("3F17F5316E2BAC89"), niv);
 381  rc = EVP_BytesToKey(cipher, md, iv /*salt*/, pword, plen, 1, key, NULL /*iv*/);
 382  if (rc != nkey)
 383      /* Error */
 384
 385  /* On success, use key and iv to initialize the cipher */
 386
 387 =head1 BUGS
 388
 389 The PEM read routines in some versions of OpenSSL will not correctly reuse
 390 an existing structure. Therefore the following:
 391
 392  PEM_read_bio_X509(bp, &x, 0, NULL);
 393
 394 where B<x> already contains a valid certificate, may not work, whereas:
 395
 396  X509_free(x);
 397  x = PEM_read_bio_X509(bp, NULL, 0, NULL);
 398
 399 is guaranteed to work.
 400
 401 =head1 RETURN VALUES
 402
 403 The read routines return either a pointer to the structure read or NULL
 404 if an error occurred.
 405
 406 The write routines return 1 for success or 0 for failure.
 407
 408 =head1 EXAMPLES
 409
 410 Although the PEM routines take several arguments in almost all applications
 411 most of them are set to 0 or NULL.
 412
 413 Read a certificate in PEM format from a BIO:
 414
 415  X509 *x;
 416
 417  x = PEM_read_bio_X509(bp, NULL, 0, NULL);
 418  if (x == NULL)
 419      /* Error */
 420
 421 Alternative method:
 422
 423  X509 *x = NULL;
 424
 425  if (!PEM_read_bio_X509(bp, &x, 0, NULL))
 426      /* Error */
 427
 428 Write a certificate to a BIO:
 429
 430  if (!PEM_write_bio_X509(bp, x))
 431      /* Error */
 432
 433 Write a private key (using traditional format) to a BIO using
 434 triple DES encryption, the pass phrase is prompted for:
 435
 436  if (!PEM_write_bio_PrivateKey(bp, key, EVP_des_ede3_cbc(), NULL, 0, 0, NULL))
 437      /* Error */
 438
 439 Write a private key (using PKCS#8 format) to a BIO using triple
 440 DES encryption, using the pass phrase "hello":
 441
 442  if (!PEM_write_bio_PKCS8PrivateKey(bp, key, EVP_des_ede3_cbc(),
 443                                     NULL, 0, 0, "hello"))
 444      /* Error */
 445
 446 Read a private key from a BIO using a pass phrase callback:
 447
 448  key = PEM_read_bio_PrivateKey(bp, NULL, pass_cb, "My Private Key");
 449  if (key == NULL)
 450      /* Error */
 451
 452 Skeleton pass phrase callback:
 453
 454  int pass_cb(char *buf, int size, int rwflag, void *u)
 455  {
 456
 457      /* We'd probably do something else if 'rwflag' is 1 */
 458      printf("Enter pass phrase for \"%s\"\n", (char *)u);
 459
 460      /* get pass phrase, length 'len' into 'tmp' */
 461      char *tmp = "hello";
 462      if (tmp == NULL) /* An error occurred */
 463          return -1;
 464
 465      size_t len = strlen(tmp);
 466
 467      if (len > size)
 468          len = size;
 469      memcpy(buf, tmp, len);
 470      return len;
 471  }
 472
 473 =head1 SEE ALSO
 474
 475 L<EVP_EncryptInit(3)>, L<EVP_BytesToKey(3)>,
 476 L<passphrase-encoding(7)>
 477
 478 =head1 HISTORY
 479
 480 The old Netscape certificate sequences were no longer documented
 481 in OpenSSL 1.1.0; applications should use the PKCS7 standard instead
 482 as they will be formally deprecated in a future releases.
 483
 484 =head1 COPYRIGHT
 485
 486 Copyright 2001-2019 The OpenSSL Project Authors. All Rights Reserved.
 487
 488 Licensed under the OpenSSL license (the "License").  You may not use
 489 this file except in compliance with the License.  You can obtain a copy
 490 in the file LICENSE in the source distribution or at
 491 L<https://www.openssl.org/source/license.html>.
 492
 493 =cut