NAME¶
PEM, PEM_read_bio_PrivateKey, PEM_read_PrivateKey, PEM_write_bio_PrivateKey,
PEM_write_PrivateKey, PEM_write_bio_PKCS8PrivateKey,
PEM_write_PKCS8PrivateKey, PEM_write_bio_PKCS8PrivateKey_nid,
PEM_write_PKCS8PrivateKey_nid, PEM_read_bio_PUBKEY, PEM_read_PUBKEY,
PEM_write_bio_PUBKEY, PEM_write_PUBKEY, PEM_read_bio_RSAPrivateKey,
PEM_read_RSAPrivateKey, PEM_write_bio_RSAPrivateKey, PEM_write_RSAPrivateKey,
PEM_read_bio_RSAPublicKey, PEM_read_RSAPublicKey, PEM_write_bio_RSAPublicKey,
PEM_write_RSAPublicKey, PEM_read_bio_RSA_PUBKEY, PEM_read_RSA_PUBKEY,
PEM_write_bio_RSA_PUBKEY, PEM_write_RSA_PUBKEY, PEM_read_bio_DSAPrivateKey,
PEM_read_DSAPrivateKey, PEM_write_bio_DSAPrivateKey, PEM_write_DSAPrivateKey,
PEM_read_bio_DSA_PUBKEY, PEM_read_DSA_PUBKEY, PEM_write_bio_DSA_PUBKEY,
PEM_write_DSA_PUBKEY, PEM_read_bio_DSAparams, PEM_read_DSAparams,
PEM_write_bio_DSAparams, PEM_write_DSAparams, PEM_read_bio_DHparams,
PEM_read_DHparams, PEM_write_bio_DHparams, PEM_write_DHparams,
PEM_read_bio_X509, PEM_read_X509, PEM_write_bio_X509, PEM_write_X509,
PEM_read_bio_X509_AUX, PEM_read_X509_AUX, PEM_write_bio_X509_AUX,
PEM_write_X509_AUX, PEM_read_bio_X509_REQ, PEM_read_X509_REQ,
PEM_write_bio_X509_REQ, PEM_write_X509_REQ, PEM_write_bio_X509_REQ_NEW,
PEM_write_X509_REQ_NEW, PEM_read_bio_X509_CRL, PEM_read_X509_CRL,
PEM_write_bio_X509_CRL, PEM_write_X509_CRL, PEM_read_bio_PKCS7,
PEM_read_PKCS7, PEM_write_bio_PKCS7, PEM_write_PKCS7,
PEM_read_bio_NETSCAPE_CERT_SEQUENCE, PEM_read_NETSCAPE_CERT_SEQUENCE,
PEM_write_bio_NETSCAPE_CERT_SEQUENCE, PEM_write_NETSCAPE_CERT_SEQUENCE - 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 algorithm 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 Dss-Parms structure as defined in RFC2459.
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.
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.
SEE ALSO¶
EVP_get_cipherbyname(3),
EVP_BytesToKey(3)