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Title "PKCS7_ENCRYPT 3"
PKCS7_ENCRYPT 3 "2023-05-30" "3.0.9" "OpenSSL"
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"NAME"
PKCS7_encrypt_ex, PKCS7_encrypt \- create a PKCS#7 envelopedData structure
"SYNOPSIS"
Header "SYNOPSIS" .Vb 1 #include <openssl/pkcs7.h> \& PKCS7 *PKCS7_encrypt_ex(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, int flags, OSSL_LIB_CTX *libctx, const char *propq); PKCS7 *PKCS7_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, int flags); .Ve
"DESCRIPTION"
Header "DESCRIPTION" \fBPKCS7_encrypt_ex() creates and returns a PKCS#7 envelopedData structure. \fIcerts is a list of recipient certificates. in is the content to be encrypted. cipher is the symmetric cipher to use. flags is an optional set of flags. The library context libctx and the property query propq are used when retrieving algorithms from providers.

Only \s-1RSA\s0 keys are supported in PKCS#7 and envelopedData so the recipient certificates supplied to this function must all contain \s-1RSA\s0 public keys, though they do not have to be signed using the \s-1RSA\s0 algorithm.

\fBEVP_des_ede3_cbc() (triple \s-1DES\s0) is the algorithm of choice for S/MIME use because most clients will support it.

Some old \*(L"export grade\*(R" clients may only support weak encryption using 40 or 64 bit \s-1RC2.\s0 These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc() respectively.

The algorithm passed in the cipher parameter must support \s-1ASN1\s0 encoding of its parameters.

Many browsers implement a \*(L"sign and encrypt\*(R" option which is simply an S/MIME envelopedData containing an S/MIME signed message. This can be readily produced by storing the S/MIME signed message in a memory \s-1BIO\s0 and passing it to \fBPKCS7_encrypt().

The following flags can be passed in the flags parameter.

If the \s-1PKCS7_TEXT\s0 flag is set \s-1MIME\s0 headers for type text/plain are prepended to the data.

Normally the supplied content is translated into \s-1MIME\s0 canonical format (as required by the S/MIME specifications) if \s-1PKCS7_BINARY\s0 is set no translation occurs. This option should be used if the supplied data is in binary format otherwise the translation will corrupt it. If \s-1PKCS7_BINARY\s0 is set then \fB\s-1PKCS7_TEXT\s0 is ignored.

If the \s-1PKCS7_STREAM\s0 flag is set a partial \s-1PKCS7\s0 structure is output suitable for streaming I/O: no data is read from the \s-1BIO\s0 in.

If the flag \s-1PKCS7_STREAM\s0 is set the returned \s-1PKCS7\s0 structure is not complete and outputting its contents via a function that does not properly finalize the \s-1PKCS7\s0 structure will give unpredictable results.

Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(), \fBPEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization can be performed by obtaining the streaming \s-1ASN1\s0 \s-1BIO\s0 directly using \fBBIO_new_PKCS7().

\fBPKCS7_encrypt() is similar to PKCS7_encrypt_ex() but uses default values of \s-1NULL\s0 for the library context libctx and the property query propq.

"RETURN VALUES"
Header "RETURN VALUES" \fBPKCS7_encrypt_ex() and PKCS7_encrypt() return either a \s-1PKCS7\s0 structure or \s-1NULL\s0 if an error occurred. The error can be obtained from ERR_get_error\|(3).
"SEE ALSO"
Header "SEE ALSO" \fBERR_get_error\|(3), PKCS7_decrypt\|(3)
"HISTORY"
Header "HISTORY" The function PKCS7_encrypt_ex() was added in OpenSSL 3.0.

The \s-1PKCS7_STREAM\s0 flag was added in OpenSSL 1.0.0.

"COPYRIGHT"
Header "COPYRIGHT" Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.