pem.pod revision 296465 
1=pod
2
3=head1 NAME
4
5PEM, PEM_read_bio_PrivateKey, PEM_read_PrivateKey, PEM_write_bio_PrivateKey,
6PEM_write_PrivateKey, PEM_write_bio_PKCS8PrivateKey, PEM_write_PKCS8PrivateKey,
7PEM_write_bio_PKCS8PrivateKey_nid, PEM_write_PKCS8PrivateKey_nid,
8PEM_read_bio_PUBKEY, PEM_read_PUBKEY, PEM_write_bio_PUBKEY, PEM_write_PUBKEY,
9PEM_read_bio_RSAPrivateKey, PEM_read_RSAPrivateKey,
10PEM_write_bio_RSAPrivateKey, PEM_write_RSAPrivateKey,
11PEM_read_bio_RSAPublicKey, PEM_read_RSAPublicKey, PEM_write_bio_RSAPublicKey,
12PEM_write_RSAPublicKey, PEM_read_bio_RSA_PUBKEY, PEM_read_RSA_PUBKEY,
13PEM_write_bio_RSA_PUBKEY, PEM_write_RSA_PUBKEY, PEM_read_bio_DSAPrivateKey,
14PEM_read_DSAPrivateKey, PEM_write_bio_DSAPrivateKey, PEM_write_DSAPrivateKey,
15PEM_read_bio_DSA_PUBKEY, PEM_read_DSA_PUBKEY, PEM_write_bio_DSA_PUBKEY,
16PEM_write_DSA_PUBKEY, PEM_read_bio_DSAparams, PEM_read_DSAparams,
17PEM_write_bio_DSAparams, PEM_write_DSAparams, PEM_read_bio_DHparams,
18PEM_read_DHparams, PEM_write_bio_DHparams, PEM_write_DHparams,
19PEM_read_bio_X509, PEM_read_X509, PEM_write_bio_X509, PEM_write_X509,
20PEM_read_bio_X509_AUX, PEM_read_X509_AUX, PEM_write_bio_X509_AUX,
21PEM_write_X509_AUX, PEM_read_bio_X509_REQ, PEM_read_X509_REQ,
22PEM_write_bio_X509_REQ, PEM_write_X509_REQ, PEM_write_bio_X509_REQ_NEW,
23PEM_write_X509_REQ_NEW, PEM_read_bio_X509_CRL, PEM_read_X509_CRL,
24PEM_write_bio_X509_CRL, PEM_write_X509_CRL, PEM_read_bio_PKCS7, PEM_read_PKCS7,
25PEM_write_bio_PKCS7, PEM_write_PKCS7, PEM_read_bio_NETSCAPE_CERT_SEQUENCE,
26PEM_read_NETSCAPE_CERT_SEQUENCE, PEM_write_bio_NETSCAPE_CERT_SEQUENCE,
27PEM_write_NETSCAPE_CERT_SEQUENCE - PEM routines
28
29=head1 SYNOPSIS
30
31 #include <openssl/pem.h>
32
33 EVP_PKEY *PEM_read_bio_PrivateKey(BIO *bp, EVP_PKEY **x,
34					pem_password_cb *cb, void *u);
35
36 EVP_PKEY *PEM_read_PrivateKey(FILE *fp, EVP_PKEY **x,
37					pem_password_cb *cb, void *u);
38
39 int PEM_write_bio_PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
40					unsigned char *kstr, int klen,
41					pem_password_cb *cb, void *u);
42
43 int PEM_write_PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
44					unsigned char *kstr, int klen,
45					pem_password_cb *cb, void *u);
46
47 int PEM_write_bio_PKCS8PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
48					char *kstr, int klen,
49					pem_password_cb *cb, void *u);
50
51 int PEM_write_PKCS8PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
52					char *kstr, int klen,
53					pem_password_cb *cb, void *u);
54
55 int PEM_write_bio_PKCS8PrivateKey_nid(BIO *bp, EVP_PKEY *x, int nid,
56					char *kstr, int klen,
57					pem_password_cb *cb, void *u);
58
59 int PEM_write_PKCS8PrivateKey_nid(FILE *fp, EVP_PKEY *x, int nid,
60					char *kstr, int klen,
61					pem_password_cb *cb, void *u);
62
63 EVP_PKEY *PEM_read_bio_PUBKEY(BIO *bp, EVP_PKEY **x,
64					pem_password_cb *cb, void *u);
65
66 EVP_PKEY *PEM_read_PUBKEY(FILE *fp, EVP_PKEY **x,
67					pem_password_cb *cb, void *u);
68
69 int PEM_write_bio_PUBKEY(BIO *bp, EVP_PKEY *x);
70 int PEM_write_PUBKEY(FILE *fp, EVP_PKEY *x);
71
72 RSA *PEM_read_bio_RSAPrivateKey(BIO *bp, RSA **x,
73					pem_password_cb *cb, void *u);
74
75 RSA *PEM_read_RSAPrivateKey(FILE *fp, RSA **x,
76					pem_password_cb *cb, void *u);
77
78 int PEM_write_bio_RSAPrivateKey(BIO *bp, RSA *x, const EVP_CIPHER *enc,
79					unsigned char *kstr, int klen,
80					pem_password_cb *cb, void *u);
81
82 int PEM_write_RSAPrivateKey(FILE *fp, RSA *x, const EVP_CIPHER *enc,
83					unsigned char *kstr, int klen,
84					pem_password_cb *cb, void *u);
85
86 RSA *PEM_read_bio_RSAPublicKey(BIO *bp, RSA **x,
87					pem_password_cb *cb, void *u);
88
89 RSA *PEM_read_RSAPublicKey(FILE *fp, RSA **x,
90					pem_password_cb *cb, void *u);
91
92 int PEM_write_bio_RSAPublicKey(BIO *bp, RSA *x);
93
94 int PEM_write_RSAPublicKey(FILE *fp, RSA *x);
95
96 RSA *PEM_read_bio_RSA_PUBKEY(BIO *bp, RSA **x,
97					pem_password_cb *cb, void *u);
98
99 RSA *PEM_read_RSA_PUBKEY(FILE *fp, RSA **x,
100					pem_password_cb *cb, void *u);
101
102 int PEM_write_bio_RSA_PUBKEY(BIO *bp, RSA *x);
103
104 int PEM_write_RSA_PUBKEY(FILE *fp, RSA *x);
105
106 DSA *PEM_read_bio_DSAPrivateKey(BIO *bp, DSA **x,
107					pem_password_cb *cb, void *u);
108
109 DSA *PEM_read_DSAPrivateKey(FILE *fp, DSA **x,
110					pem_password_cb *cb, void *u);
111
112 int PEM_write_bio_DSAPrivateKey(BIO *bp, DSA *x, const EVP_CIPHER *enc,
113					unsigned char *kstr, int klen,
114					pem_password_cb *cb, void *u);
115
116 int PEM_write_DSAPrivateKey(FILE *fp, DSA *x, const EVP_CIPHER *enc,
117					unsigned char *kstr, int klen,
118					pem_password_cb *cb, void *u);
119
120 DSA *PEM_read_bio_DSA_PUBKEY(BIO *bp, DSA **x,
121					pem_password_cb *cb, void *u);
122
123 DSA *PEM_read_DSA_PUBKEY(FILE *fp, DSA **x,
124					pem_password_cb *cb, void *u);
125
126 int PEM_write_bio_DSA_PUBKEY(BIO *bp, DSA *x);
127
128 int PEM_write_DSA_PUBKEY(FILE *fp, DSA *x);
129
130 DSA *PEM_read_bio_DSAparams(BIO *bp, DSA **x, pem_password_cb *cb, void *u);
131
132 DSA *PEM_read_DSAparams(FILE *fp, DSA **x, pem_password_cb *cb, void *u);
133
134 int PEM_write_bio_DSAparams(BIO *bp, DSA *x);
135
136 int PEM_write_DSAparams(FILE *fp, DSA *x);
137
138 DH *PEM_read_bio_DHparams(BIO *bp, DH **x, pem_password_cb *cb, void *u);
139
140 DH *PEM_read_DHparams(FILE *fp, DH **x, pem_password_cb *cb, void *u);
141
142 int PEM_write_bio_DHparams(BIO *bp, DH *x);
143
144 int PEM_write_DHparams(FILE *fp, DH *x);
145
146 X509 *PEM_read_bio_X509(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
147
148 X509 *PEM_read_X509(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
149
150 int PEM_write_bio_X509(BIO *bp, X509 *x);
151
152 int PEM_write_X509(FILE *fp, X509 *x);
153
154 X509 *PEM_read_bio_X509_AUX(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
155
156 X509 *PEM_read_X509_AUX(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
157
158 int PEM_write_bio_X509_AUX(BIO *bp, X509 *x);
159
160 int PEM_write_X509_AUX(FILE *fp, X509 *x);
161
162 X509_REQ *PEM_read_bio_X509_REQ(BIO *bp, X509_REQ **x,
163					pem_password_cb *cb, void *u);
164
165 X509_REQ *PEM_read_X509_REQ(FILE *fp, X509_REQ **x,
166					pem_password_cb *cb, void *u);
167
168 int PEM_write_bio_X509_REQ(BIO *bp, X509_REQ *x);
169
170 int PEM_write_X509_REQ(FILE *fp, X509_REQ *x);
171
172 int PEM_write_bio_X509_REQ_NEW(BIO *bp, X509_REQ *x);
173
174 int PEM_write_X509_REQ_NEW(FILE *fp, X509_REQ *x);
175
176 X509_CRL *PEM_read_bio_X509_CRL(BIO *bp, X509_CRL **x,
177					pem_password_cb *cb, void *u);
178 X509_CRL *PEM_read_X509_CRL(FILE *fp, X509_CRL **x,
179					pem_password_cb *cb, void *u);
180 int PEM_write_bio_X509_CRL(BIO *bp, X509_CRL *x);
181 int PEM_write_X509_CRL(FILE *fp, X509_CRL *x);
182
183 PKCS7 *PEM_read_bio_PKCS7(BIO *bp, PKCS7 **x, pem_password_cb *cb, void *u);
184
185 PKCS7 *PEM_read_PKCS7(FILE *fp, PKCS7 **x, pem_password_cb *cb, void *u);
186
187 int PEM_write_bio_PKCS7(BIO *bp, PKCS7 *x);
188
189 int PEM_write_PKCS7(FILE *fp, PKCS7 *x);
190
191 NETSCAPE_CERT_SEQUENCE *PEM_read_bio_NETSCAPE_CERT_SEQUENCE(BIO *bp,
192						NETSCAPE_CERT_SEQUENCE **x,
193						pem_password_cb *cb, void *u);
194
195 NETSCAPE_CERT_SEQUENCE *PEM_read_NETSCAPE_CERT_SEQUENCE(FILE *fp,
196						NETSCAPE_CERT_SEQUENCE **x,
197						pem_password_cb *cb, void *u);
198
199 int PEM_write_bio_NETSCAPE_CERT_SEQUENCE(BIO *bp, NETSCAPE_CERT_SEQUENCE *x);
200
201 int PEM_write_NETSCAPE_CERT_SEQUENCE(FILE *fp, NETSCAPE_CERT_SEQUENCE *x);
202
203=head1 DESCRIPTION
204
205The PEM functions read or write structures in PEM format. In
206this sense PEM format is simply base64 encoded data surrounded
207by header lines.
208
209For more details about the meaning of arguments see the
210B<PEM FUNCTION ARGUMENTS> section.
211
212Each operation has four functions associated with it. For
213clarity the term "B<foobar> functions" will be used to collectively
214refer to the PEM_read_bio_foobar(), PEM_read_foobar(),
215PEM_write_bio_foobar() and PEM_write_foobar() functions.
216
217The B<PrivateKey> functions read or write a private key in
218PEM format using an EVP_PKEY structure. The write routines use
219"traditional" private key format and can handle both RSA and DSA
220private keys. The read functions can additionally transparently
221handle PKCS#8 format encrypted and unencrypted keys too.
222
223PEM_write_bio_PKCS8PrivateKey() and PEM_write_PKCS8PrivateKey()
224write a private key in an EVP_PKEY structure in PKCS#8
225EncryptedPrivateKeyInfo format using PKCS#5 v2.0 password based encryption
226algorithms. The B<cipher> argument specifies the encryption algoritm to
227use: unlike all other PEM routines the encryption is applied at the
228PKCS#8 level and not in the PEM headers. If B<cipher> is NULL then no
229encryption is used and a PKCS#8 PrivateKeyInfo structure is used instead.
230
231PEM_write_bio_PKCS8PrivateKey_nid() and PEM_write_PKCS8PrivateKey_nid()
232also write out a private key as a PKCS#8 EncryptedPrivateKeyInfo however
233it uses PKCS#5 v1.5 or PKCS#12 encryption algorithms instead. The algorithm
234to use is specified in the B<nid> parameter and should be the NID of the
235corresponding OBJECT IDENTIFIER (see NOTES section).
236
237The B<PUBKEY> functions process a public key using an EVP_PKEY
238structure. The public key is encoded as a SubjectPublicKeyInfo
239structure.
240
241The B<RSAPrivateKey> functions process an RSA private key using an
242RSA structure. It handles the same formats as the B<PrivateKey>
243functions but an error occurs if the private key is not RSA.
244
245The B<RSAPublicKey> functions process an RSA public key using an
246RSA structure. The public key is encoded using a PKCS#1 RSAPublicKey
247structure.
248
249The B<RSA_PUBKEY> functions also process an RSA public key using
250an RSA structure. However the public key is encoded using a
251SubjectPublicKeyInfo structure and an error occurs if the public
252key is not RSA.
253
254The B<DSAPrivateKey> functions process a DSA private key using a
255DSA structure. It handles the same formats as the B<PrivateKey>
256functions but an error occurs if the private key is not DSA.
257
258The B<DSA_PUBKEY> functions process a DSA public key using
259a DSA structure. The public key is encoded using a
260SubjectPublicKeyInfo structure and an error occurs if the public
261key is not DSA.
262
263The B<DSAparams> functions process DSA parameters using a DSA
264structure. The parameters are encoded using a Dss-Parms structure
265as defined in RFC2459.
266
267The B<DHparams> functions process DH parameters using a DH
268structure. The parameters are encoded using a PKCS#3 DHparameter
269structure.
270
271The B<X509> functions process an X509 certificate using an X509
272structure. They will also process a trusted X509 certificate but
273any trust settings are discarded.
274
275The B<X509_AUX> functions process a trusted X509 certificate using
276an X509 structure. 
277
278The B<X509_REQ> and B<X509_REQ_NEW> functions process a PKCS#10
279certificate request using an X509_REQ structure. The B<X509_REQ>
280write functions use B<CERTIFICATE REQUEST> in the header whereas
281the B<X509_REQ_NEW> functions use B<NEW CERTIFICATE REQUEST>
282(as required by some CAs). The B<X509_REQ> read functions will
283handle either form so there are no B<X509_REQ_NEW> read functions.
284
285The B<X509_CRL> functions process an X509 CRL using an X509_CRL
286structure.
287
288The B<PKCS7> functions process a PKCS#7 ContentInfo using a PKCS7
289structure.
290
291The B<NETSCAPE_CERT_SEQUENCE> functions process a Netscape Certificate
292Sequence using a NETSCAPE_CERT_SEQUENCE structure.
293
294=head1 PEM FUNCTION ARGUMENTS
295
296The PEM functions have many common arguments.
297
298The B<bp> BIO parameter (if present) specifies the BIO to read from
299or write to.
300
301The B<fp> FILE parameter (if present) specifies the FILE pointer to
302read from or write to.
303
304The PEM read functions all take an argument B<TYPE **x> and return
305a B<TYPE *> pointer. Where B<TYPE> is whatever structure the function
306uses. If B<x> is NULL then the parameter is ignored. If B<x> is not
307NULL but B<*x> is NULL then the structure returned will be written
308to B<*x>. If neither B<x> nor B<*x> is NULL then an attempt is made
309to reuse the structure at B<*x> (but see BUGS and EXAMPLES sections).
310Irrespective of the value of B<x> a pointer to the structure is always
311returned (or NULL if an error occurred).
312
313The PEM functions which write private keys take an B<enc> parameter
314which specifies the encryption algorithm to use, encryption is done
315at the PEM level. If this parameter is set to NULL then the private
316key is written in unencrypted form.
317
318The B<cb> argument is the callback to use when querying for the pass
319phrase used for encrypted PEM structures (normally only private keys).
320
321For the PEM write routines if the B<kstr> parameter is not NULL then
322B<klen> bytes at B<kstr> are used as the passphrase and B<cb> is
323ignored.
324
325If the B<cb> parameters is set to NULL and the B<u> parameter is not
326NULL then the B<u> parameter is interpreted as a null terminated string
327to use as the passphrase. If both B<cb> and B<u> are NULL then the
328default callback routine is used which will typically prompt for the
329passphrase on the current terminal with echoing turned off.
330
331The default passphrase callback is sometimes inappropriate (for example
332in a GUI application) so an alternative can be supplied. The callback
333routine has the following form:
334
335 int cb(char *buf, int size, int rwflag, void *u);
336
337B<buf> is the buffer to write the passphrase to. B<size> is the maximum
338length of the passphrase (i.e. the size of buf). B<rwflag> is a flag
339which is set to 0 when reading and 1 when writing. A typical routine
340will ask the user to verify the passphrase (for example by prompting
341for it twice) if B<rwflag> is 1. The B<u> parameter has the same
342value as the B<u> parameter passed to the PEM routine. It allows
343arbitrary data to be passed to the callback by the application
344(for example a window handle in a GUI application). The callback
345B<must> return the number of characters in the passphrase or 0 if
346an error occurred.
347
348=head1 EXAMPLES
349
350Although the PEM routines take several arguments in almost all applications
351most of them are set to 0 or NULL.
352
353Read a certificate in PEM format from a BIO:
354
355 X509 *x;
356 x = PEM_read_bio_X509(bp, NULL, 0, NULL);
357 if (x == NULL)
358	{
359	/* Error */
360	}
361
362Alternative method:
363
364 X509 *x = NULL;
365 if (!PEM_read_bio_X509(bp, &x, 0, NULL))
366	{
367	/* Error */
368	}
369
370Write a certificate to a BIO:
371
372 if (!PEM_write_bio_X509(bp, x))
373	{
374	/* Error */
375	}
376
377Write an unencrypted private key to a FILE pointer:
378
379 if (!PEM_write_PrivateKey(fp, key, NULL, NULL, 0, 0, NULL))
380	{
381	/* Error */
382	}
383
384Write a private key (using traditional format) to a BIO using
385triple DES encryption, the pass phrase is prompted for:
386
387 if (!PEM_write_bio_PrivateKey(bp, key, EVP_des_ede3_cbc(), NULL, 0, 0, NULL))
388	{
389	/* Error */
390	}
391
392Write a private key (using PKCS#8 format) to a BIO using triple
393DES encryption, using the pass phrase "hello":
394
395 if (!PEM_write_bio_PKCS8PrivateKey(bp, key, EVP_des_ede3_cbc(), NULL, 0, 0, "hello"))
396	{
397	/* Error */
398	}
399
400Read a private key from a BIO using the pass phrase "hello":
401
402 key = PEM_read_bio_PrivateKey(bp, NULL, 0, "hello");
403 if (key == NULL)
404	{
405	/* Error */
406	}
407
408Read a private key from a BIO using a pass phrase callback:
409
410 key = PEM_read_bio_PrivateKey(bp, NULL, pass_cb, "My Private Key");
411 if (key == NULL)
412	{
413	/* Error */
414	}
415
416Skeleton pass phrase callback:
417
418 int pass_cb(char *buf, int size, int rwflag, void *u);
419	{
420	int len;
421	char *tmp;
422	/* We'd probably do something else if 'rwflag' is 1 */
423	printf("Enter pass phrase for \"%s\"\n", u);
424
425	/* get pass phrase, length 'len' into 'tmp' */
426	tmp = "hello";
427	len = strlen(tmp);
428
429	if (len <= 0) return 0;
430	/* if too long, truncate */
431	if (len > size) len = size;
432	memcpy(buf, tmp, len);
433	return len;
434	}
435
436=head1 NOTES
437
438The old B<PrivateKey> write routines are retained for compatibility.
439New applications should write private keys using the
440PEM_write_bio_PKCS8PrivateKey() or PEM_write_PKCS8PrivateKey() routines
441because they are more secure (they use an iteration count of 2048 whereas
442the traditional routines use a count of 1) unless compatibility with older
443versions of OpenSSL is important.
444
445The B<PrivateKey> read routines can be used in all applications because
446they handle all formats transparently.
447
448A frequent cause of problems is attempting to use the PEM routines like
449this:
450
451 X509 *x;
452 PEM_read_bio_X509(bp, &x, 0, NULL);
453
454this is a bug because an attempt will be made to reuse the data at B<x>
455which is an uninitialised pointer.
456
457=head1 PEM ENCRYPTION FORMAT
458
459This old B<PrivateKey> routines use a non standard technique for encryption.
460
461The private key (or other data) takes the following form: 
462
463 -----BEGIN RSA PRIVATE KEY-----
464 Proc-Type: 4,ENCRYPTED
465 DEK-Info: DES-EDE3-CBC,3F17F5316E2BAC89
466
467 ...base64 encoded data...
468 -----END RSA PRIVATE KEY-----
469
470The line beginning DEK-Info contains two comma separated pieces of information:
471the encryption algorithm name as used by EVP_get_cipherbyname() and an 8
472byte B<salt> encoded as a set of hexadecimal digits.
473
474After this is the base64 encoded encrypted data.
475
476The encryption key is determined using EVP_BytesToKey(), using B<salt> and an
477iteration count of 1. The IV used is the value of B<salt> and *not* the IV
478returned by EVP_BytesToKey().
479
480=head1 BUGS
481
482The PEM read routines in some versions of OpenSSL will not correctly reuse
483an existing structure. Therefore the following:
484
485 PEM_read_bio_X509(bp, &x, 0, NULL);
486
487where B<x> already contains a valid certificate, may not work, whereas: 
488
489 X509_free(x);
490 x = PEM_read_bio_X509(bp, NULL, 0, NULL);
491
492is guaranteed to work.
493
494=head1 RETURN CODES
495
496The read routines return either a pointer to the structure read or NULL
497if an error occurred.
498
499The write routines return 1 for success or 0 for failure.
500
501=head1 SEE ALSO
502
503L<EVP_get_cipherbyname(3)|EVP_get_cipherbyname>, L<EVP_BytesToKey(3)|EVP_BytesToKey(3)>
504