PEM_READ_BIO_PRIVATEKEY(3) | Library Functions Manual | PEM_READ_BIO_PRIVATEKEY(3)

# NAME

`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_PKCS8`, `PEM_read_PKCS8`, `PEM_write_bio_PKCS8`, `PEM_write_PKCS8`, `PEM_read_bio_PKCS8_PRIV_KEY_INFO`, `PEM_read_PKCS8_PRIV_KEY_INFO`, `PEM_write_bio_PKCS8_PRIV_KEY_INFO`, `PEM_write_PKCS8_PRIV_KEY_INFO`, `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_ECPKParameters`, `PEM_read_ECPKParameters`, `PEM_write_bio_ECPKParameters`, `PEM_write_ECPKParameters`, `PEM_read_bio_ECPrivateKey`, `PEM_read_ECPrivateKey`, `PEM_write_bio_ECPrivateKey`, `PEM_write_ECPrivateKey`, `PEM_read_bio_EC_PUBKEY`, `PEM_read_EC_PUBKEY`, `PEM_write_bio_EC_PUBKEY`, `PEM_write_EC_PUBKEY`, `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_CMS`, `PEM_read_bio_CMS`, `PEM_write_CMS`, `PEM_write_bio_CMS` — PEM routines

# SYNOPSIS

library “libcrypto”
`#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);

X509_SIG *
`PEM_read_bio_PKCS8`(BIO *bp, X509_SIG **x, pem_password_cb *cb, void *u);

X509_SIG *
`PEM_read_PKCS8`(FILE *fp, X509_SIG **x, pem_password_cb *cb, void *u);

int
`PEM_write_bio_PKCS8`(BIO *bp, X509_SIG *x);

int
`PEM_write_PKCS8`(FILE *fp, X509_SIG *x);

PKCS8_PRIV_KEY_INFO *
`PEM_read_bio_PKCS8_PRIV_KEY_INFO`(BIO *bp, PKCS8_PRIV_KEY_INFO **x, pem_password_cb *cb, void *u);

PKCS8_PRIV_KEY_INFO *
`PEM_read_PKCS8_PRIV_KEY_INFO`(FILE *fp, PKCS8_PRIV_KEY_INFO **x, pem_password_cb *cb, void *u);

int
`PEM_write_bio_PKCS8_PRIV_KEY_INFO`(BIO *bp, PKCS8_PRIV_KEY_INFO *x);

int
`PEM_write_PKCS8_PRIV_KEY_INFO`(FILE *fp, PKCS8_PRIV_KEY_INFO *x);

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);

EC_GROUP *
`PEM_read_bio_ECPKParameters`(BIO *bp, EC_GROUP **x, pem_password_cb *cb, void *u);

EC_GROUP *
`PEM_read_ECPKParameters`(FILE *fp, EC_GROUP **x, pem_password_cb *cb, void *u);

int
`PEM_write_bio_ECPKParameters`(BIO *bp, const EC_GROUP *x);

int
`PEM_write_ECPKParameters`(FILE *fp, const EC_GROUP *x);

EC_KEY *
`PEM_read_bio_ECPrivateKey`(BIO *bp, EC_KEY **key, pem_password_cb *cb, void *u);

EC_KEY *
`PEM_read_ECPrivateKey`(FILE *fp, EC_KEY **eckey, pem_password_cb *cb, void *u);

int
`PEM_write_bio_ECPrivateKey`(BIO *bp, EC_KEY *x, const EVP_CIPHER *enc, unsigned char *kstr, int klen, pem_password_cb *cb, void *u);

int
`PEM_write_ECPrivateKey`(FILE *fp, EC_KEY *x, const EVP_CIPHER *enc, unsigned char *kstr, int klen, pem_password_cb *cb, void *u);

EC_KEY *
`PEM_read_bio_EC_PUBKEY`(BIO *bp, EC_KEY **x, pem_password_cb *cb, void *u);

EC_KEY *
`PEM_read_EC_PUBKEY`(FILE *fp, EC_KEY **x, pem_password_cb *cb, void *u);

int
`PEM_write_bio_EC_PUBKEY`(BIO *bp, EC_KEY *x);

int
`PEM_write_EC_PUBKEY`(FILE *fp, EC_KEY *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);

`#include <openssl/cms.h>`

CMS_ContentInfo *
`PEM_read_CMS`(FILE *fp, CMS_ContentInfo **x, pem_password_cb *cb, void *u);

CMS_ContentInfo *
`PEM_read_bio_CMS`(BIO *bp, CMS_ContentInfo **x, pem_password_cb *cb, void *u);

int
`PEM_write_CMS`(FILE *fp, const CMS_ContentInfo *x);

int
`PEM_write_bio_CMS`(BIO *bp, const CMS_ContentInfo *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; see PEM_read(3) for more details.

For more details about the meaning of arguments see the PEM function arguments section.

Each operation has four functions associated with it. For brevity the term “TYPE functions” will be used to collectively refer to the `PEM_read_bio_TYPE`(), `PEM_read_TYPE`(), `PEM_write_bio_TYPE`(), and `PEM_write_TYPE`() functions. If no set of specific functions exists for a given type, PEM_ASN1_read(3) can be used instead.

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 enc 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 enc 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 they use 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.

The PKCS8 functions process an encrypted private key using an X509_SIG structure and the d2i_X509_SIG(3) function.

The PKCS8_PRIV_KEY_INFO functions process a private key using a PKCS8_PRIV_KEY_INFO structure.

The PUBKEY functions process a public key using an EVP_PKEY structure. The public key is encoded as an ASN.1 SubjectPublicKeyInfo structure.

The RSAPrivateKey functions process an RSA private key using an RSA structure. They handle 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 an ASN.1 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. They handle 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 an ASN.1 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 RFC 2459.

The DHparams functions process DH parameters using a DH structure. The parameters are encoded using a PKCS#3 DHparameter structure.

The ECPKParameters functions process EC parameters using an EC_GROUP structure and the d2i_ECPKParameters(3) function.

The ECPrivateKey functions process an EC private key using an EC_KEY structure.

The EC_PUBKEY functions process an EC public key using an EC_KEY 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 CMS functions process a CMS_ContentInfo structure.

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.

## PEM function arguments

The PEM functions have many common arguments.

The bp parameter specifies the BIO to read from or write to.

The fp parameter specifies the FILE pointer to read from or write to.

The PEM read functions all take a pointer to pointer argument x and return a pointer of the same type. 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 are `NULL`, then an attempt is made to reuse the structure at *x, but see the 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 optional arguments u and cb are a passphrase used for encrypting a PEM structure or a callback to obtain the passphrase; see pem_password_cb(3) for details.

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.

## PEM encryption format

These 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 with “DEK-Info” contains two comma separated pieces of information: the encryption algorithm name as used by EVP_get_cipherbyname(3) 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(3), using the salt and an iteration count of 1. The IV used is the value of the salt and *not* the IV returned by EVP_BytesToKey(3).

# RETURN VALUES

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.

# 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:

    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)
    {
    	char	*tmp;
    	size_t	 len;

    	/* We'd probably do something else if 'rwflag' is 1 */
    	printf("Enter pass phrase for \"%s\"\n", u);

    	/*
    	 * Instead of the following line, get the passphrase
    	 * from the user in some way.
    	 */
    	tmp = "hello";
    	if (tmp == NULL) /* An error occurred. */
    		return -1;

    	len = strlen(tmp);
    	if (len == 0) /* Treat an empty passphrase as an error, too. */
    		return -1;

    	/* if too long, truncate */
    	if (len > size)
    		len = size;
    	memcpy(buf, tmp, len);
    	return len;
    }

# SEE ALSO

BIO_new(3), DSA_new(3), PEM_ASN1_read(3), PEM_bytes_read_bio(3), PEM_read(3), PEM_read_SSL_SESSION(3), PEM_write_bio_CMS_stream(3), PEM_write_bio_PKCS7_stream(3), PEM_X509_INFO_read_bio(3), RSA_new(3), X509_CRL_new(3), X509_REQ_new(3), X509_SIG_new(3)

# HISTORY

`PEM_read_X509`() and `PEM_write_X509`() appeared in SSLeay 0.4 or earlier. `PEM_read_X509_REQ`(), `PEM_write_X509_REQ`(), `PEM_read_X509_CRL`(), and `PEM_write_X509_CRL`() first appeared in SSLeay 0.4.4. `PEM_read_RSAPrivateKey`(), `PEM_write_RSAPrivateKey`(), `PEM_read_DHparams`(), `PEM_write_DHparams`(), `PEM_read_PKCS7`(), and `PEM_write_PKCS7`() first appeared in SSLeay 0.5.1. `PEM_read_bio_PrivateKey`(), `PEM_read_PrivateKey`(), `PEM_read_bio_RSAPrivateKey`(), `PEM_write_bio_RSAPrivateKey`(), `PEM_read_bio_DSAPrivateKey`(), `PEM_read_DSAPrivateKey`(), `PEM_write_bio_DSAPrivateKey`(), `PEM_write_DSAPrivateKey`(), `PEM_read_bio_DHparams`(), `PEM_write_bio_DHparams`(), `PEM_read_bio_X509`(), `PEM_write_bio_X509`(), `PEM_read_bio_X509_REQ`(), `PEM_write_bio_X509_REQ`(), `PEM_read_bio_X509_CRL`(), `PEM_write_bio_X509_CRL`(), `PEM_read_bio_PKCS7`(), and `PEM_write_bio_PKCS7`() first appeared in SSLeay 0.6.0. `PEM_write_bio_PrivateKey`(), `PEM_write_PrivateKey`(), `PEM_read_bio_DSAparams`(), `PEM_read_DSAparams`(), `PEM_write_bio_DSAparams`(), and `PEM_write_DSAparams`() first appeared in SSLeay 0.8.0. `PEM_read_bio_RSAPublicKey`(), `PEM_read_RSAPublicKey`(), `PEM_write_bio_RSAPublicKey`(), and `PEM_write_RSAPublicKey`() first appeared in SSLeay 0.8.1. All these functions have been available since OpenBSD 2.4.

`PEM_write_bio_PKCS8PrivateKey`(), `PEM_write_PKCS8PrivateKey`(), `PEM_read_bio_PKCS8`(), `PEM_read_PKCS8`(), `PEM_write_bio_PKCS8`(), `PEM_write_PKCS8`(), `PEM_read_bio_PKCS8_PRIV_KEY_INFO`(), `PEM_read_PKCS8_PRIV_KEY_INFO`(), `PEM_write_bio_PKCS8_PRIV_KEY_INFO`(), `PEM_write_PKCS8_PRIV_KEY_INFO`(),

`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_RSA_PUBKEY`(), `PEM_read_RSA_PUBKEY`(), `PEM_write_bio_RSA_PUBKEY`(), `PEM_write_RSA_PUBKEY`(), `PEM_read_bio_DSA_PUBKEY`(), `PEM_read_DSA_PUBKEY`(), `PEM_write_bio_DSA_PUBKEY`(), `PEM_write_DSA_PUBKEY`(), `PEM_write_bio_X509_REQ_NEW`(), `PEM_write_X509_REQ_NEW`(), `PEM_read_bio_X509_AUX`(), `PEM_read_X509_AUX`(), `PEM_write_bio_X509_AUX`(), and `PEM_write_X509_AUX`() first appeared in OpenSSL 0.9.5 and have been available since OpenBSD 2.7.

`PEM_read_bio_ECPKParameters`(), `PEM_read_ECPKParameters`(), `PEM_write_bio_ECPKParameters`(), `PEM_write_ECPKParameters`(), `PEM_read_bio_ECPrivateKey`(), `PEM_read_ECPrivateKey`(), `PEM_write_bio_ECPrivateKey`(), `PEM_write_ECPrivateKey`(), `PEM_read_bio_EC_PUBKEY`(), `PEM_read_EC_PUBKEY`(), `PEM_write_bio_EC_PUBKEY`(), and `PEM_write_EC_PUBKEY`() first appeared in OpenSSL 0.9.8 and have been available since OpenBSD 4.5.

`PEM_read_CMS`(), `PEM_read_bio_CMS`(), `PEM_write_CMS`(), and `PEM_write_bio_CMS`() first appeared in OpenSSL 0.9.8h and have been available since OpenBSD 6.7.

# CAVEATS

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.

These functions make no assumption regarding the pass phrase received from the password callback. It will simply be treated as a byte sequence.

# BUGS

The PEM read routines in some versions of OpenSSL will not correctly reuse an existing structure. Therefore

`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.

July 16, 2025 | Debian