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pem(3) OpenSSL 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: KEY----Proc-Type:
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,3F17F5316E2BAC89
...base64 encoded data...
-----END RSA PRIVATE KEY-----The KEY----The
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.
0.9.7l 2004-03-21 pem(3)
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