476 lines
15 KiB
Text
476 lines
15 KiB
Text
=pod
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=head1 NAME
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PEM - PEM routines
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=head1 SYNOPSIS
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#include <openssl/pem.h>
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EVP_PKEY *PEM_read_bio_PrivateKey(BIO *bp, EVP_PKEY **x,
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pem_password_cb *cb, void *u);
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EVP_PKEY *PEM_read_PrivateKey(FILE *fp, EVP_PKEY **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
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unsigned char *kstr, int klen,
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pem_password_cb *cb, void *u);
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int PEM_write_PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
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unsigned char *kstr, int klen,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_PKCS8PrivateKey(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc,
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char *kstr, int klen,
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pem_password_cb *cb, void *u);
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int PEM_write_PKCS8PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
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char *kstr, int klen,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_PKCS8PrivateKey_nid(BIO *bp, EVP_PKEY *x, int nid,
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char *kstr, int klen,
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pem_password_cb *cb, void *u);
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int PEM_write_PKCS8PrivateKey_nid(FILE *fp, EVP_PKEY *x, int nid,
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char *kstr, int klen,
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pem_password_cb *cb, void *u);
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EVP_PKEY *PEM_read_bio_PUBKEY(BIO *bp, EVP_PKEY **x,
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pem_password_cb *cb, void *u);
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EVP_PKEY *PEM_read_PUBKEY(FILE *fp, EVP_PKEY **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_PUBKEY(BIO *bp, EVP_PKEY *x);
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int PEM_write_PUBKEY(FILE *fp, EVP_PKEY *x);
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RSA *PEM_read_bio_RSAPrivateKey(BIO *bp, RSA **x,
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pem_password_cb *cb, void *u);
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RSA *PEM_read_RSAPrivateKey(FILE *fp, RSA **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_RSAPrivateKey(BIO *bp, RSA *x, const EVP_CIPHER *enc,
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unsigned char *kstr, int klen,
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pem_password_cb *cb, void *u);
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int PEM_write_RSAPrivateKey(FILE *fp, RSA *x, const EVP_CIPHER *enc,
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unsigned char *kstr, int klen,
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pem_password_cb *cb, void *u);
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RSA *PEM_read_bio_RSAPublicKey(BIO *bp, RSA **x,
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pem_password_cb *cb, void *u);
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RSA *PEM_read_RSAPublicKey(FILE *fp, RSA **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_RSAPublicKey(BIO *bp, RSA *x);
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int PEM_write_RSAPublicKey(FILE *fp, RSA *x);
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RSA *PEM_read_bio_RSA_PUBKEY(BIO *bp, RSA **x,
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pem_password_cb *cb, void *u);
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RSA *PEM_read_RSA_PUBKEY(FILE *fp, RSA **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_RSA_PUBKEY(BIO *bp, RSA *x);
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int PEM_write_RSA_PUBKEY(FILE *fp, RSA *x);
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DSA *PEM_read_bio_DSAPrivateKey(BIO *bp, DSA **x,
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pem_password_cb *cb, void *u);
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DSA *PEM_read_DSAPrivateKey(FILE *fp, DSA **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_DSAPrivateKey(BIO *bp, DSA *x, const EVP_CIPHER *enc,
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unsigned char *kstr, int klen,
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pem_password_cb *cb, void *u);
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int PEM_write_DSAPrivateKey(FILE *fp, DSA *x, const EVP_CIPHER *enc,
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unsigned char *kstr, int klen,
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pem_password_cb *cb, void *u);
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DSA *PEM_read_bio_DSA_PUBKEY(BIO *bp, DSA **x,
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pem_password_cb *cb, void *u);
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DSA *PEM_read_DSA_PUBKEY(FILE *fp, DSA **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_DSA_PUBKEY(BIO *bp, DSA *x);
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int PEM_write_DSA_PUBKEY(FILE *fp, DSA *x);
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DSA *PEM_read_bio_DSAparams(BIO *bp, DSA **x, pem_password_cb *cb, void *u);
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DSA *PEM_read_DSAparams(FILE *fp, DSA **x, pem_password_cb *cb, void *u);
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int PEM_write_bio_DSAparams(BIO *bp, DSA *x);
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int PEM_write_DSAparams(FILE *fp, DSA *x);
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DH *PEM_read_bio_DHparams(BIO *bp, DH **x, pem_password_cb *cb, void *u);
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DH *PEM_read_DHparams(FILE *fp, DH **x, pem_password_cb *cb, void *u);
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int PEM_write_bio_DHparams(BIO *bp, DH *x);
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int PEM_write_DHparams(FILE *fp, DH *x);
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X509 *PEM_read_bio_X509(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
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X509 *PEM_read_X509(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
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int PEM_write_bio_X509(BIO *bp, X509 *x);
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int PEM_write_X509(FILE *fp, X509 *x);
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X509 *PEM_read_bio_X509_AUX(BIO *bp, X509 **x, pem_password_cb *cb, void *u);
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X509 *PEM_read_X509_AUX(FILE *fp, X509 **x, pem_password_cb *cb, void *u);
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int PEM_write_bio_X509_AUX(BIO *bp, X509 *x);
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int PEM_write_X509_AUX(FILE *fp, X509 *x);
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X509_REQ *PEM_read_bio_X509_REQ(BIO *bp, X509_REQ **x,
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pem_password_cb *cb, void *u);
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X509_REQ *PEM_read_X509_REQ(FILE *fp, X509_REQ **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_X509_REQ(BIO *bp, X509_REQ *x);
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int PEM_write_X509_REQ(FILE *fp, X509_REQ *x);
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int PEM_write_bio_X509_REQ_NEW(BIO *bp, X509_REQ *x);
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int PEM_write_X509_REQ_NEW(FILE *fp, X509_REQ *x);
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X509_CRL *PEM_read_bio_X509_CRL(BIO *bp, X509_CRL **x,
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pem_password_cb *cb, void *u);
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X509_CRL *PEM_read_X509_CRL(FILE *fp, X509_CRL **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_X509_CRL(BIO *bp, X509_CRL *x);
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int PEM_write_X509_CRL(FILE *fp, X509_CRL *x);
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PKCS7 *PEM_read_bio_PKCS7(BIO *bp, PKCS7 **x, pem_password_cb *cb, void *u);
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PKCS7 *PEM_read_PKCS7(FILE *fp, PKCS7 **x, pem_password_cb *cb, void *u);
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int PEM_write_bio_PKCS7(BIO *bp, PKCS7 *x);
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int PEM_write_PKCS7(FILE *fp, PKCS7 *x);
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NETSCAPE_CERT_SEQUENCE *PEM_read_bio_NETSCAPE_CERT_SEQUENCE(BIO *bp,
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NETSCAPE_CERT_SEQUENCE **x,
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pem_password_cb *cb, void *u);
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NETSCAPE_CERT_SEQUENCE *PEM_read_NETSCAPE_CERT_SEQUENCE(FILE *fp,
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NETSCAPE_CERT_SEQUENCE **x,
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pem_password_cb *cb, void *u);
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int PEM_write_bio_NETSCAPE_CERT_SEQUENCE(BIO *bp, NETSCAPE_CERT_SEQUENCE *x);
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int PEM_write_NETSCAPE_CERT_SEQUENCE(FILE *fp, NETSCAPE_CERT_SEQUENCE *x);
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=head1 DESCRIPTION
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The PEM functions read or write structures in PEM format. In
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this sense PEM format is simply base64 encoded data surrounded
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by header lines.
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For more details about the meaning of arguments see the
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B<PEM FUNCTION ARGUMENTS> section.
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Each operation has four functions associated with it. For
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clarity the term "B<foobar> functions" will be used to collectively
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refer to the PEM_read_bio_foobar(), PEM_read_foobar(),
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PEM_write_bio_foobar() and PEM_write_foobar() functions.
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The B<PrivateKey> functions read or write a private key in
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PEM format using an EVP_PKEY structure. The write routines use
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"traditional" private key format and can handle both RSA and DSA
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private keys. The read functions can additionally transparently
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handle PKCS#8 format encrypted and unencrypted keys too.
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PEM_write_bio_PKCS8PrivateKey() and PEM_write_PKCS8PrivateKey()
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write a private key in an EVP_PKEY structure in PKCS#8
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EncryptedPrivateKeyInfo format using PKCS#5 v2.0 password based encryption
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algorithms. The B<cipher> argument specifies the encryption algoritm to
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use: unlike all other PEM routines the encryption is applied at the
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PKCS#8 level and not in the PEM headers. If B<cipher> is NULL then no
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encryption is used and a PKCS#8 PrivateKeyInfo structure is used instead.
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PEM_write_bio_PKCS8PrivateKey_nid() and PEM_write_PKCS8PrivateKey_nid()
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also write out a private key as a PKCS#8 EncryptedPrivateKeyInfo however
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it uses PKCS#5 v1.5 or PKCS#12 encryption algorithms instead. The algorithm
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to use is specified in the B<nid> parameter and should be the NID of the
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corresponding OBJECT IDENTIFIER (see NOTES section).
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The B<PUBKEY> functions process a public key using an EVP_PKEY
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structure. The public key is encoded as a SubjectPublicKeyInfo
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structure.
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The B<RSAPrivateKey> functions process an RSA private key using an
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RSA structure. It handles the same formats as the B<PrivateKey>
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functions but an error occurs if the private key is not RSA.
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The B<RSAPublicKey> functions process an RSA public key using an
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RSA structure. The public key is encoded using a PKCS#1 RSAPublicKey
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structure.
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The B<RSA_PUBKEY> functions also process an RSA public key using
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an RSA structure. However the public key is encoded using a
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SubjectPublicKeyInfo structure and an error occurs if the public
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key is not RSA.
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The B<DSAPrivateKey> functions process a DSA private key using a
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DSA structure. It handles the same formats as the B<PrivateKey>
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functions but an error occurs if the private key is not DSA.
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The B<DSA_PUBKEY> functions process a DSA public key using
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a DSA structure. The public key is encoded using a
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SubjectPublicKeyInfo structure and an error occurs if the public
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key is not DSA.
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The B<DSAparams> functions process DSA parameters using a DSA
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structure. The parameters are encoded using a foobar structure.
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The B<DHparams> functions process DH parameters using a DH
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structure. The parameters are encoded using a PKCS#3 DHparameter
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structure.
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The B<X509> functions process an X509 certificate using an X509
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structure. They will also process a trusted X509 certificate but
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any trust settings are discarded.
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The B<X509_AUX> functions process a trusted X509 certificate using
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an X509 structure.
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The B<X509_REQ> and B<X509_REQ_NEW> functions process a PKCS#10
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certificate request using an X509_REQ structure. The B<X509_REQ>
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write functions use B<CERTIFICATE REQUEST> in the header whereas
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the B<X509_REQ_NEW> functions use B<NEW CERTIFICATE REQUEST>
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(as required by some CAs). The B<X509_REQ> read functions will
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handle either form so there are no B<X509_REQ_NEW> read functions.
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The B<X509_CRL> functions process an X509 CRL using an X509_CRL
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structure.
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The B<PKCS7> functions process a PKCS#7 ContentInfo using a PKCS7
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structure.
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The B<NETSCAPE_CERT_SEQUENCE> functions process a Netscape Certificate
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Sequence using a NETSCAPE_CERT_SEQUENCE structure.
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=head1 PEM FUNCTION ARGUMENTS
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The PEM functions have many common arguments.
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The B<bp> BIO parameter (if present) specifies the BIO to read from
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or write to.
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The B<fp> FILE parameter (if present) specifies the FILE pointer to
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read from or write to.
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The PEM read functions all take an argument B<TYPE **x> and return
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a B<TYPE *> pointer. Where B<TYPE> is whatever structure the function
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uses. If B<x> is NULL then the parameter is ignored. If B<x> is not
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NULL but B<*x> is NULL then the structure returned will be written
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to B<*x>. If neither B<x> nor B<*x> is NULL then an attempt is made
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to reuse the structure at B<*x> (but see BUGS and EXAMPLES sections).
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Irrespective of the value of B<x> a pointer to the structure is always
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returned (or NULL if an error occurred).
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The PEM functions which write private keys take an B<enc> parameter
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which specifies the encryption algorithm to use, encryption is done
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at the PEM level. If this parameter is set to NULL then the private
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key is written in unencrypted form.
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The B<cb> argument is the callback to use when querying for the pass
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phrase used for encrypted PEM structures (normally only private keys).
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For the PEM write routines if the B<kstr> parameter is not NULL then
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B<klen> bytes at B<kstr> are used as the passphrase and B<cb> is
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ignored.
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If the B<cb> parameters is set to NULL and the B<u> parameter is not
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NULL then the B<u> parameter is interpreted as a null terminated string
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to use as the passphrase. If both B<cb> and B<u> are NULL then the
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default callback routine is used which will typically prompt for the
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passphrase on the current terminal with echoing turned off.
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The default passphrase callback is sometimes inappropriate (for example
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in a GUI application) so an alternative can be supplied. The callback
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routine has the following form:
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int cb(char *buf, int size, int rwflag, void *u);
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B<buf> is the buffer to write the passphrase to. B<size> is the maximum
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length of the passphrase (i.e. the size of buf). B<rwflag> is a flag
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which is set to 0 when reading and 1 when writing. A typical routine
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will ask the user to verify the passphrase (for example by prompting
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for it twice) if B<rwflag> is 1. The B<u> parameter has the same
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value as the B<u> parameter passed to the PEM routine. It allows
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arbitrary data to be passed to the callback by the application
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(for example a window handle in a GUI application). The callback
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B<must> return the number of characters in the passphrase or 0 if
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an error occurred.
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=head1 EXAMPLES
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Although the PEM routines take several arguments in almost all applications
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most of them are set to 0 or NULL.
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Read a certificate in PEM format from a BIO:
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X509 *x;
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x = PEM_read_bio_X509(bp, NULL, 0, NULL);
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if (x == NULL)
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{
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/* Error */
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}
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Alternative method:
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X509 *x = NULL;
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if (!PEM_read_bio_X509(bp, &x, 0, NULL))
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{
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/* Error */
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}
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Write a certificate to a BIO:
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if (!PEM_write_bio_X509(bp, x))
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{
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/* Error */
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}
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Write an unencrypted private key to a FILE pointer:
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if (!PEM_write_PrivateKey(fp, key, NULL, NULL, 0, 0, NULL))
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{
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/* Error */
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}
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Write a private key (using traditional format) to a BIO using
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triple DES encryption, the pass phrase is prompted for:
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if (!PEM_write_bio_PrivateKey(bp, key, EVP_des_ede3_cbc(), NULL, 0, 0, NULL))
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{
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/* Error */
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}
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Write a private key (using PKCS#8 format) to a BIO using triple
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DES encryption, using the pass phrase "hello":
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if (!PEM_write_bio_PKCS8PrivateKey(bp, key, EVP_des_ede3_cbc(), NULL, 0, 0, "hello"))
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{
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/* Error */
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}
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Read a private key from a BIO using the pass phrase "hello":
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key = PEM_read_bio_PrivateKey(bp, NULL, 0, "hello");
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if (key == NULL)
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{
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/* Error */
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}
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Read a private key from a BIO using a pass phrase callback:
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key = PEM_read_bio_PrivateKey(bp, NULL, pass_cb, "My Private Key");
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if (key == NULL)
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{
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/* Error */
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}
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Skeleton pass phrase callback:
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int pass_cb(char *buf, int size, int rwflag, void *u);
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{
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int len;
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char *tmp;
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/* We'd probably do something else if 'rwflag' is 1 */
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printf("Enter pass phrase for \"%s\"\n", u);
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/* get pass phrase, length 'len' into 'tmp' */
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tmp = "hello";
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len = strlen(tmp);
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if (len <= 0) return 0;
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/* if too long, truncate */
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if (len > size) len = size;
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memcpy(buf, tmp, len);
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return len;
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}
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=head1 NOTES
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The old B<PrivateKey> write routines are retained for compatibility.
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New applications should write private keys using the
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PEM_write_bio_PKCS8PrivateKey() or PEM_write_PKCS8PrivateKey() routines
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because they are more secure (they use an iteration count of 2048 whereas
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the traditional routines use a count of 1) unless compatibility with older
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versions of OpenSSL is important.
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The B<PrivateKey> read routines can be used in all applications because
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they handle all formats transparently.
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A frequent cause of problems is attempting to use the PEM routines like
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this:
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X509 *x;
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PEM_read_bio_X509(bp, &x, 0, NULL);
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this is a bug because an attempt will be made to reuse the data at B<x>
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which is an uninitialised pointer.
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=head1 PEM ENCRYPTION FORMAT
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This old B<PrivateKey> routines use a non standard technique for encryption.
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The private key (or other data) takes the following form:
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-----BEGIN RSA PRIVATE KEY-----
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Proc-Type: 4,ENCRYPTED
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DEK-Info: DES-EDE3-CBC,3F17F5316E2BAC89
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...base64 encoded data...
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-----END RSA PRIVATE KEY-----
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The line beginning DEK-Info contains two comma separated pieces of information:
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the encryption algorithm name as used by EVP_get_cipherbyname() and an 8
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byte B<salt> encoded as a set of hexadecimal digits.
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After this is the base64 encoded encrypted data.
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The encryption key is determined using EVP_bytestokey(), using B<salt> and an
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iteration count of 1. The IV used is the value of B<salt> and *not* the IV
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returned by EVP_bytestokey().
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=head1 BUGS
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The PEM read routines in some versions of OpenSSL will not correctly reuse
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an existing structure. Therefore the following:
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PEM_read_bio_X509(bp, &x, 0, NULL);
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where B<x> already contains a valid certificate, may not work, whereas:
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X509_free(x);
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x = PEM_read_bio_X509(bp, NULL, 0, NULL);
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is guaranteed to work.
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=head1 RETURN CODES
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The read routines return either a pointer to the structure read or NULL
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is an error occurred.
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The write routines return 1 for success or 0 for failure.
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