/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/crypto
pem(3) 21/Mar/2004 (0.9.7e) pem(3)
NAME
PEM - PEM routines
SYNOPSIS
#include <openssl/pem.h>
EVP_PKEY *PEM_read_bio_PrivateKey(BIO *bp, EVP_PKEY **x,
pem_password_cb *cb, void *u);
EVP_PKEY *PEM_read_PrivateKey(FILE *fp, EVP_PKEY **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
unsigned char *kstr, int klen,
pem_password_cb *cb, void *u);
int PEM_write_PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
unsigned char *kstr, int klen,
pem_password_cb *cb, void *u);
int PEM_write_bio_PKCS8PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
char *kstr, int klen,
pem_password_cb *cb, void *u);
int PEM_write_PKCS8PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
char *kstr, int klen,
pem_password_cb *cb, void *u);
int PEM_write_bio_PKCS8PrivateKey_nid(BIO *bp, EVP_PKEY *x, int nid,
char *kstr, int klen,
pem_password_cb *cb, void *u);
int PEM_write_PKCS8PrivateKey_nid(FILE *fp, EVP_PKEY *x, int nid,
char *kstr, int klen,
pem_password_cb *cb, void *u);
EVP_PKEY *PEM_read_bio_PUBKEY(BIO *bp, EVP_PKEY **x,
pem_password_cb *cb, void *u);
EVP_PKEY *PEM_read_PUBKEY(FILE *fp, EVP_PKEY **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_PUBKEY(BIO *bp, EVP_PKEY *x);
int PEM_write_PUBKEY(FILE *fp, EVP_PKEY *x);
RSA *PEM_read_bio_RSAPrivateKey(BIO *bp, RSA **x,
pem_password_cb *cb, void *u);
RSA *PEM_read_RSAPrivateKey(FILE *fp, RSA **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_RSAPrivateKey(BIO *bp, RSA *x, const EVP_CIPHER *enc,
unsigned char *kstr, int klen,
pem_password_cb *cb, void *u);
int PEM_write_RSAPrivateKey(FILE *fp, RSA *x, const EVP_CIPHER *enc,
unsigned char *kstr, int klen,
pem_password_cb *cb, void *u);
RSA *PEM_read_bio_RSAPublicKey(BIO *bp, RSA **x,
pem_password_cb *cb, void *u);
RSA *PEM_read_RSAPublicKey(FILE *fp, RSA **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_RSAPublicKey(BIO *bp, RSA *x);
int PEM_write_RSAPublicKey(FILE *fp, RSA *x);
RSA *PEM_read_bio_RSA_PUBKEY(BIO *bp, RSA **x,
pem_password_cb *cb, void *u);
RSA *PEM_read_RSA_PUBKEY(FILE *fp, RSA **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_RSA_PUBKEY(BIO *bp, RSA *x);
int PEM_write_RSA_PUBKEY(FILE *fp, RSA *x);
DSA *PEM_read_bio_DSAPrivateKey(BIO *bp, DSA **x,
pem_password_cb *cb, void *u);
DSA *PEM_read_DSAPrivateKey(FILE *fp, DSA **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_DSAPrivateKey(BIO *bp, DSA *x, const EVP_CIPHER *enc,
unsigned char *kstr, int klen,
pem_password_cb *cb, void *u);
int PEM_write_DSAPrivateKey(FILE *fp, DSA *x, const EVP_CIPHER *enc,
unsigned char *kstr, int klen,
pem_password_cb *cb, void *u);
DSA *PEM_read_bio_DSA_PUBKEY(BIO *bp, DSA **x,
pem_password_cb *cb, void *u);
DSA *PEM_read_DSA_PUBKEY(FILE *fp, DSA **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_DSA_PUBKEY(BIO *bp, DSA *x);
int PEM_write_DSA_PUBKEY(FILE *fp, DSA *x);
DSA *PEM_read_bio_DSAparams(BIO *bp, DSA **x, pem_password_cb *cb, void *u);
DSA *PEM_read_DSAparams(FILE *fp, DSA **x, pem_password_cb *cb, void *u);
int PEM_write_bio_DSAparams(BIO *bp, DSA *x);
int PEM_write_DSAparams(FILE *fp, DSA *x);
DH *PEM_read_bio_DHparams(BIO *bp, DH **x, pem_password_cb *cb, void *u);
DH *PEM_read_DHparams(FILE *fp, DH **x, pem_password_cb *cb, void *u);
int PEM_write_bio_DHparams(BIO *bp, DH *x);
int PEM_write_DHparams(FILE *fp, DH *x);
X509 *PEM_read_bio_X509(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
X509 *PEM_read_X509(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
int PEM_write_bio_X509(BIO *bp, X509 *x);
int PEM_write_X509(FILE *fp, X509 *x);
X509 *PEM_read_bio_X509_AUX(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
X509 *PEM_read_X509_AUX(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
int PEM_write_bio_X509_AUX(BIO *bp, X509 *x);
int PEM_write_X509_AUX(FILE *fp, X509 *x);
X509_REQ *PEM_read_bio_X509_REQ(BIO *bp, X509_REQ **x,
pem_password_cb *cb, void *u);
X509_REQ *PEM_read_X509_REQ(FILE *fp, X509_REQ **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_X509_REQ(BIO *bp, X509_REQ *x);
int PEM_write_X509_REQ(FILE *fp, X509_REQ *x);
int PEM_write_bio_X509_REQ_NEW(BIO *bp, X509_REQ *x);
int PEM_write_X509_REQ_NEW(FILE *fp, X509_REQ *x);
X509_CRL *PEM_read_bio_X509_CRL(BIO *bp, X509_CRL **x,
pem_password_cb *cb, void *u);
X509_CRL *PEM_read_X509_CRL(FILE *fp, X509_CRL **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_X509_CRL(BIO *bp, X509_CRL *x);
int PEM_write_X509_CRL(FILE *fp, X509_CRL *x);
PKCS7 *PEM_read_bio_PKCS7(BIO *bp, PKCS7 **x, pem_password_cb *cb, void *u);
PKCS7 *PEM_read_PKCS7(FILE *fp, PKCS7 **x, pem_password_cb *cb, void *u);
int PEM_write_bio_PKCS7(BIO *bp, PKCS7 *x);
int PEM_write_PKCS7(FILE *fp, PKCS7 *x);
NETSCAPE_CERT_SEQUENCE *PEM_read_bio_NETSCAPE_CERT_SEQUENCE(BIO *bp,
NETSCAPE_CERT_SEQUENCE **x,
pem_password_cb *cb, void *u);
NETSCAPE_CERT_SEQUENCE *PEM_read_NETSCAPE_CERT_SEQUENCE(FILE *fp,
NETSCAPE_CERT_SEQUENCE **x,
pem_password_cb *cb, void *u);
int PEM_write_bio_NETSCAPE_CERT_SEQUENCE(BIO *bp, NETSCAPE_CERT_SEQUENCE *x);
int PEM_write_NETSCAPE_CERT_SEQUENCE(FILE *fp, NETSCAPE_CERT_SEQUENCE *x);
DESCRIPTION
The PEM functions read or write structures in PEM format. In
this sense PEM format is simply base64 encoded data
surrounded by header lines.
For more details about the meaning of arguments see the PEM
FUNCTION ARGUMENTS section.
Each operation has four functions associated with it. For
clarity the term "foobar functions" will be used to
collectively refer to the PEM_read_bio_foobar(),
PEM_read_foobar(), PEM_write_bio_foobar() and
PEM_write_foobar() functions.
The PrivateKey functions read or write a private key in PEM
format using an EVP_PKEY structure. The write routines use
"traditional" private key format and can handle both RSA and
DSA private keys. The read functions can additionally
transparently handle PKCS#8 format encrypted and unencrypted
keys too.
PEM_write_bio_PKCS8PrivateKey() and
PEM_write_PKCS8PrivateKey() write a private key in an
EVP_PKEY structure in PKCS#8 EncryptedPrivateKeyInfo format
using PKCS#5 v2.0 password based encryption algorithms. The
cipher argument specifies the encryption algoritm to use:
unlike all other PEM routines the encryption is applied at
the PKCS#8 level and not in the PEM headers. If cipher is
NULL then no encryption is used and a PKCS#8 PrivateKeyInfo
structure is used instead.
PEM_write_bio_PKCS8PrivateKey_nid() and
PEM_write_PKCS8PrivateKey_nid() also write out a private key
as a PKCS#8 EncryptedPrivateKeyInfo however it uses PKCS#5
v1.5 or PKCS#12 encryption algorithms instead. The algorithm
to use is specified in the nid parameter and should be the
NID of the corresponding OBJECT IDENTIFIER (see NOTES
section).
The PUBKEY functions process a public key using an EVP_PKEY
structure. The public key is encoded as a
SubjectPublicKeyInfo structure.
The RSAPrivateKey functions process an RSA private key using
an RSA structure. It handles the same formats as the
PrivateKey functions but an error occurs if the private key
is not RSA.
The RSAPublicKey functions process an RSA public key using
an RSA structure. The public key is encoded using a PKCS#1
RSAPublicKey structure.
The RSA_PUBKEY functions also process an RSA public key
using an RSA structure. However the public key is encoded
using a SubjectPublicKeyInfo structure and an error occurs
if the public key is not RSA.
The DSAPrivateKey functions process a DSA private key using
a DSA structure. It handles the same formats as the
PrivateKey functions but an error occurs if the private key
is not DSA.
The DSA_PUBKEY functions process a DSA public key using a
DSA structure. The public key is encoded using a
SubjectPublicKeyInfo structure and an error occurs if the
public key is not DSA.
The DSAparams functions process DSA parameters using a DSA
structure. The parameters are encoded using a foobar
structure.
The DHparams functions process DH parameters using a DH
structure. The parameters are encoded using a PKCS#3
DHparameter structure.
The X509 functions process an X509 certificate using an X509
structure. They will also process a trusted X509 certificate
but any trust settings are discarded.
The X509_AUX functions process a trusted X509 certificate
using an X509 structure.
The X509_REQ and X509_REQ_NEW functions process a PKCS#10
certificate request using an X509_REQ structure. The
X509_REQ write functions use CERTIFICATE REQUEST in the
header whereas the X509_REQ_NEW functions use NEW
CERTIFICATE REQUEST (as required by some CAs). The X509_REQ
read functions will handle either form so there are no
X509_REQ_NEW read functions.
The X509_CRL functions process an X509 CRL using an X509_CRL
structure.
The PKCS7 functions process a PKCS#7 ContentInfo using a
PKCS7 structure.
The NETSCAPE_CERT_SEQUENCE functions process a Netscape
Certificate Sequence using a NETSCAPE_CERT_SEQUENCE
structure.
PEM FUNCTION ARGUMENTS
The PEM functions have many common arguments.
The bp BIO parameter (if present) specifies the BIO to read
from or write to.
The fp FILE parameter (if present) specifies the FILE
pointer to read from or write to.
The PEM read functions all take an argument TYPE **x and
return a TYPE * pointer. Where TYPE is whatever structure
the function uses. If x is NULL then the parameter is
ignored. If x is not NULL but *x is NULL then the structure
returned will be written to *x. If neither x nor *x is NULL
then an attempt is made to reuse the structure at *x (but
see BUGS and EXAMPLES sections). Irrespective of the value
of x a pointer to the structure is always returned (or NULL
if an error occurred).
The PEM functions which write private keys take an enc
parameter which specifies the encryption algorithm to use,
encryption is done at the PEM level. If this parameter is
set to NULL then the private key is written in unencrypted
form.
The cb argument is the callback to use when querying for the
pass phrase used for encrypted PEM structures (normally only
private keys).
For the PEM write routines if the kstr parameter is not NULL
then klen bytes at kstr are used as the passphrase and cb is
ignored.
If the cb parameters is set to NULL and the u parameter is
not NULL then the u parameter is interpreted as a null
terminated string to use as the passphrase. If both cb and u
are NULL then the default callback routine is used which
will typically prompt for the passphrase on the current
terminal with echoing turned off.
The default passphrase callback is sometimes inappropriate
(for example in a GUI application) so an alternative can be
supplied. The callback routine has the following form:
int cb(char *buf, int size, int rwflag, void *u);
buf is the buffer to write the passphrase to. size is the
maximum length of the passphrase (i.e. the size of buf).
rwflag is a flag which is set to 0 when reading and 1 when
writing. A typical routine will ask the user to verify the
passphrase (for example by prompting for it twice) if rwflag
is 1. The u parameter has the same value as the u parameter
passed to the PEM routine. It allows arbitrary data to be
passed to the callback by the application (for example a
window handle in a GUI application). The callback must
return the number of characters in the passphrase or 0 if an
error occurred.
EXAMPLES
Although the PEM routines take several arguments in almost
all applications most of them are set to 0 or NULL.
Read a certificate in PEM format from a BIO:
X509 *x;
x = PEM_read_bio_X509(bp, NULL, 0, NULL);
if (x == NULL)
{
/* Error */
}
Alternative method:
X509 *x = NULL;
if (!PEM_read_bio_X509(bp, &x, 0, NULL))
{
/* Error */
}
Write a certificate to a BIO:
if (!PEM_write_bio_X509(bp, x))
{
/* Error */
}
Write an unencrypted private key to a FILE pointer:
if (!PEM_write_PrivateKey(fp, key, NULL, NULL, 0, 0, NULL))
{
/* Error */
}
Write a private key (using traditional format) to a BIO
using triple DES encryption, the pass phrase is prompted
for:
if (!PEM_write_bio_PrivateKey(bp, key, EVP_des_ede3_cbc(), NULL, 0, 0, NULL))
{
/* Error */
}
Write a private key (using PKCS#8 format) to a BIO using
triple DES encryption, using the pass phrase "hello":
if (!PEM_write_bio_PKCS8PrivateKey(bp, key, EVP_des_ede3_cbc(), NULL, 0, 0, "hello"))
{
/* Error */
}
Read a private key from a BIO using the pass phrase "hello":
key = PEM_read_bio_PrivateKey(bp, NULL, 0, "hello");
if (key == NULL)
{
/* Error */
}
Read a private key from a BIO using a pass phrase callback:
key = PEM_read_bio_PrivateKey(bp, NULL, pass_cb, "My Private Key");
if (key == NULL)
{
/* Error */
}
Skeleton pass phrase callback:
int pass_cb(char *buf, int size, int rwflag, void *u);
{
int len;
char *tmp;
/* We'd probably do something else if 'rwflag' is 1 */
printf("Enter pass phrase for \"%s\"\n", u);
/* get pass phrase, length 'len' into 'tmp' */
tmp = "hello";
len = strlen(tmp);
if (len <= 0) return 0;
/* if too long, truncate */
if (len > size) len = size;
memcpy(buf, tmp, len);
return len;
}
NOTES
The old PrivateKey write routines are retained for
compatibility. New applications should write private keys
using the PEM_write_bio_PKCS8PrivateKey() or
PEM_write_PKCS8PrivateKey() routines because they are more
secure (they use an iteration count of 2048 whereas the
traditional routines use a count of 1) unless compatibility
with older versions of OpenSSL is important.
The PrivateKey read routines can be used in all applications
because they handle all formats transparently.
A frequent cause of problems is attempting to use the PEM
routines like this:
X509 *x;
PEM_read_bio_X509(bp, &x, 0, NULL);
this is a bug because an attempt will be made to reuse the
data at x which is an uninitialised pointer.
PEM ENCRYPTION FORMAT
This old PrivateKey routines use a non standard technique
for encryption.
The private key (or other data) takes the following form:
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,3F17F5316E2BAC89
...base64 encoded data...
-----END RSA PRIVATE KEY-----
The line beginning DEK-Info contains two comma separated
pieces of information: the encryption algorithm name as
used by EVP_get_cipherbyname() and an 8 byte salt encoded as
a set of hexadecimal digits.
After this is the base64 encoded encrypted data.
The encryption key is determined using EVP_bytestokey(),
using salt and an iteration count of 1. The IV used is the
value of salt and *not* the IV returned by EVP_bytestokey().
BUGS
The PEM read routines in some versions of OpenSSL will not
correctly reuse an existing structure. Therefore the
following:
PEM_read_bio_X509(bp, &x, 0, NULL);
where x already contains a valid certificate, may not work,
whereas:
X509_free(x);
x = PEM_read_bio_X509(bp, NULL, 0, NULL);
is guaranteed to work.
RETURN CODES
The read routines return either a pointer to the structure
read or NULL if an error occurred.
The write routines return 1 for success or 0 for failure.
Page 10 (printed 10/20/05)