pem(3)pem(3)NAMEpem - 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,
int klen,
unsigned char *kstr,
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_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_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(
ILE *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_NET‐
SCAPE_CERT_SEQUENCE(
BIO *bp,
NETSCAPE_CERT_SEQUENCE **x,
pem_password_cb *cb,
void *u ); NETSCAPE_CERT_SEQUENCE *PEM_read_NET‐
SCAPE_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_NET‐
SCAPE_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.
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 func‐
tions can transparently handle PKCS#8 format encrypted and unencrypted
keys too.
The PEM_write_bio_PKCS8PrivateKey() and PEM_write_PKCS8PrivateKey()
functions write a private key in an EVP_PKEY structure in PKCS#8
EncryptedPrivateKeyInfo format using PKCS#5 v2.0 password based encryp‐
tion 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.
The PEM_write_bio_PKCS8PrivateKey_nid() and PEM_write_PKCS8Pri‐
vateKey_nid() functions also write out a private key as a PKCS#8
EncryptedPrivateKeyInfo however it uses PKCS#5 v1.5 or PKCS#12 encryp‐
tion 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 SubjectPublicKey‐
Info 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 struc‐
ture. 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 set‐
tings 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 struc‐
ture.
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 IO 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 (see NOTES
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 parameter 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 rou‐
tine will ask the user to verify the passphrase (for example by prompt‐
ing 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.
NOTES
The PEM read routines in some versions of OpenSSL will not correctly
reuse an existing structure. Therefore the following may not work where
x already contains a valid certificate: PEM_read_bio(bp, &x, 0, NULL);
However, the following is guaranteed to work:
X509_free(x); x =3D PEM_read_bio(bp, NULL, 0, NULL);
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, unless compatibility with older versions
of OpenSSL is important. (They use an iteration count of 2048, whereas
the traditional routines use a count of 1.) The PrivateKey read rou‐
tines can be used in all applications because they handle all formats
transparently. A frequent cause of problems is attempting to use the
PEM routines in the following manner:
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 uninitialized pointer.
RETURN VALUES
The read routines return either a pointer to the structure read or NULL
is an error occurred.
The write routines return 1 for success or 0 for failure.
EXAMPLES
Although the PEM routines take several arguments in almost all applica‐
tions most of them are set to 0 or NULL.
Read a certificate in PEM format from a BIO:
X509 *x; x = PEM_read_bio(bp, NULL, 0, NULL); if (x == NULL)
{
}
Alternative method:
X509 *x = NULL; if (!PEM_read_bio_X509(bp, &x, 0, NULL))
{
}
Write a certificate to a BIO:
if (!PEM_write_bio_X509(bp, x))
{
}
Write an unencrypted private key to a FILE pointer:
if (!PEM_write_PrivateKey(fp, key, NULL, NULL, 0, 0, NULL))
{
}
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))
{
}
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"))
{
}
Read a private key from a BIO using the pass phrase ``hello'':
key = PEM_read_bio_PrivateKey(bp, NULL, 0, "hello"); if (key == NULL)
{
}
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)
{
}
Skeleton pass phrase callback:
int pass_cb(char *buf, int size, int rwflag, void *u);
{
int len;
char *tmp;
printf("Enter pass phrase for \"%s\"\n", u);
tmp = "hello";
len = strlen(tmp);
if (len <= 0) return 0;
if (len > size) len = size;
memcpy(buf, tmp, len);
return len;
}
pem(3)
