Edit File: CMS_encrypt.3
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" .Vb 1 \& CMS_encrypt \- create a CMS envelopedData structure .Ve .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/cms.h> \& \& CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, unsigned int flags); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBCMS_encrypt()\fR creates and returns a \s-1CMS\s0 EnvelopedData structure. \fBcerts\fR is a list of recipient certificates. \fBin\fR is the content to be encrypted. \&\fBcipher\fR is the symmetric cipher to use. \fBflags\fR is an optional set of flags. .SH "NOTES" .IX Header "NOTES" Only certificates carrying \s-1RSA,\s0 Diffie-Hellman or \s-1EC\s0 keys are supported by this function. .PP \&\fBEVP_des_ede3_cbc()\fR (triple \s-1DES\s0) is the algorithm of choice for S/MIME use because most clients will support it. .PP The algorithm passed in the \fBcipher\fR parameter must support \s-1ASN1\s0 encoding of its parameters. .PP 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 \&\fBCMS_encrypt()\fR. .PP The following flags can be passed in the \fBflags\fR parameter. .PP If the \fB\s-1CMS_TEXT\s0\fR flag is set \s-1MIME\s0 headers for type \fBtext/plain\fR are prepended to the data. .PP Normally the supplied content is translated into \s-1MIME\s0 canonical format (as required by the S/MIME specifications) if \fB\s-1CMS_BINARY\s0\fR 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 \fB\s-1CMS_BINARY\s0\fR is set then \&\fB\s-1CMS_TEXT\s0\fR is ignored. .PP OpenSSL will by default identify recipient certificates using issuer name and serial number. If \fB\s-1CMS_USE_KEYID\s0\fR is set it will use the subject key identifier value instead. An error occurs if all recipient certificates do not have a subject key identifier extension. .PP If the \fB\s-1CMS_STREAM\s0\fR flag is set a partial \fBCMS_ContentInfo\fR structure is returned suitable for streaming I/O: no data is read from the \s-1BIO\s0 \fBin\fR. .PP If the \fB\s-1CMS_PARTIAL\s0\fR flag is set a partial \fBCMS_ContentInfo\fR structure is returned to which additional recipients and attributes can be added before finalization. .PP The data being encrypted is included in the CMS_ContentInfo structure, unless \&\fB\s-1CMS_DETACHED\s0\fR is set in which case it is omitted. This is rarely used in practice and is not supported by \fBSMIME_write_CMS()\fR. .SH "NOTES" .IX Header "NOTES" If the flag \fB\s-1CMS_STREAM\s0\fR is set the returned \fBCMS_ContentInfo\fR structure is \&\fBnot\fR complete and outputting its contents via a function that does not properly finalize the \fBCMS_ContentInfo\fR structure will give unpredictable results. .PP Several functions including \fBSMIME_write_CMS()\fR, \fBi2d_CMS_bio_stream()\fR, \&\fBPEM_write_bio_CMS_stream()\fR finalize the structure. Alternatively finalization can be performed by obtaining the streaming \s-1ASN1\s0 \fB\s-1BIO\s0\fR directly using \&\fBBIO_new_CMS()\fR. .PP The recipients specified in \fBcerts\fR use a \s-1CMS\s0 KeyTransRecipientInfo info structure. KEKRecipientInfo is also supported using the flag \fB\s-1CMS_PARTIAL\s0\fR and \fBCMS_add0_recipient_key()\fR. .PP The parameter \fBcerts\fR may be \s-1NULL\s0 if \fB\s-1CMS_PARTIAL\s0\fR is set and recipients added later using \fBCMS_add1_recipient_cert()\fR or \fBCMS_add0_recipient_key()\fR. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBCMS_encrypt()\fR returns either a CMS_ContentInfo structure or \s-1NULL\s0 if an error occurred. The error can be obtained from \fBERR_get_error\fR\|(3). .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBERR_get_error\fR\|(3), \fBCMS_decrypt\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" \&\fBCMS_decrypt()\fR was added to OpenSSL 0.9.8 The \fB\s-1CMS_STREAM\s0\fR flag was first supported in OpenSSL 1.0.0.