xref: /openssl/doc/man3/OSSL_ENCODER_to_bio.pod (revision c249f487)
1=pod
2
3=head1 NAME
4
5OSSL_ENCODER_to_data,
6OSSL_ENCODER_to_bio,
7OSSL_ENCODER_to_fp
8- Routines to perform an encoding
9
10=head1 SYNOPSIS
11
12 #include <openssl/encoder.h>
13
14 int OSSL_ENCODER_to_data(OSSL_ENCODER_CTX *ctx, unsigned char **pdata,
15                          size_t *pdata_len);
16 int OSSL_ENCODER_to_bio(OSSL_ENCODER_CTX *ctx, BIO *out);
17 int OSSL_ENCODER_to_fp(OSSL_ENCODER_CTX *ctx, FILE *fp);
18
19Feature availability macros:
20
21=over 4
22
23=item OSSL_ENCODER_to_fp() is only available when B<OPENSSL_NO_STDIO>
24is undefined.
25
26=back
27
28=head1 DESCRIPTION
29
30OSSL_ENCODER_to_data() runs the encoding process for the context I<ctx>,
31with the output going to the I<*pdata> and I<*pdata_len>.
32If I<*pdata> is NULL when OSSL_ENCODER_to_data() is called, a buffer will be
33allocated using L<OPENSSL_zalloc(3)>, and I<*pdata> will be set to point at
34the start of that buffer, and I<*pdata_len> will be assigned its length when
35OSSL_ENCODER_to_data() returns.
36If I<*pdata> is non-NULL when OSSL_ENCODER_to_data() is called, I<*pdata_len>
37is assumed to have its size.  In this case, I<*pdata> will be set to point
38after the encoded bytes, and I<*pdata_len> will be assigned the number of
39remaining bytes.
40
41OSSL_ENCODER_to_bio() runs the encoding process for the context I<ctx>, with
42the output going to the B<BIO> I<out>.
43
44OSSL_ENCODER_to_fp() does the same thing as OSSL_ENCODER_to_bio(), except
45that the output is going to the B<FILE> I<fp>.
46
47=for comment Know your encoder!
48
49For OSSL_ENCODER_to_bio() and OSSL_ENCODER_to_fp(), the application is
50required to set up the B<BIO> or B<FILE> properly, for example to have
51it in text or binary mode as is appropriate for the encoder output type.
52
53=head1 RETURN VALUES
54
55OSSL_ENCODER_to_bio(), OSSL_ENCODER_to_fp() and OSSL_ENCODER_to_data()
56return 1 on success, or 0 on failure.
57
58=head1 EXAMPLES
59
60To encode a pkey as PKCS#8 with PEM format into a bio:
61
62 OSSL_ENCODER_CTX *ectx;
63 const char *format = "PEM";
64 const char *structure = "PrivateKeyInfo"; /* PKCS#8 structure */
65 const unsigned char *pass = "my password";
66
67 ectx = OSSL_ENCODER_CTX_new_for_pkey(pkey,
68                                      OSSL_KEYMGMT_SELECT_KEYPAIR
69                                      | OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
70                                      format, structure,
71                                      NULL);
72 if (ectx == NULL) {
73     /* error: no suitable potential encoders found */
74 }
75 if (pass != NULL)
76     OSSL_ENCODER_CTX_set_passphrase(ectx, pass, strlen(pass));
77 if (OSSL_ENCODER_to_bio(ectx, bio)) {
78     /* pkey was successfully encoded into the bio */
79 } else {
80     /* encoding failure */
81 }
82 OSSL_ENCODER_CTX_free(ectx);
83
84To encode a pkey as PKCS#8 with DER format encrypted with
85AES-256-CBC into a buffer:
86
87 OSSL_ENCODER_CTX *ectx;
88 const char *format = "DER";
89 const char *structure = "PrivateKeyInfo"; /* PKCS#8 structure */
90 const unsigned char *pass = "my password";
91 unsigned char *data = NULL;
92 size_t datalen;
93
94 ectx = OSSL_ENCODER_CTX_new_for_pkey(pkey,
95                                      OSSL_KEYMGMT_SELECT_KEYPAIR
96                                      | OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
97                                      format, structure,
98                                      NULL);
99 if (ectx == NULL) {
100     /* error: no suitable potential encoders found */
101 }
102 if (pass != NULL) {
103     OSSL_ENCODER_CTX_set_passphrase(ectx, pass, strlen(pass));
104     OSSL_ENCODER_CTX_set_cipher(ctx, "AES-256-CBC", NULL);
105 }
106 if (OSSL_ENCODER_to_data(ectx, &data, &datalen)) {
107     /*
108      * pkey was successfully encoded into a newly allocated
109      * data buffer
110      */
111 } else {
112     /* encoding failure */
113 }
114 OSSL_ENCODER_CTX_free(ectx);
115
116=head1 SEE ALSO
117
118L<provider(7)>, L<OSSL_ENCODER_CTX(3)>
119
120=head1 HISTORY
121
122The functions described here were added in OpenSSL 3.0.
123
124=head1 COPYRIGHT
125
126Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
127
128Licensed under the Apache License 2.0 (the "License").  You may not use
129this file except in compliance with the License.  You can obtain a copy
130in the file LICENSE in the source distribution or at
131L<https://www.openssl.org/source/license.html>.
132
133=cut
134