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cms_decrypt(3ssl) [bsd man page]

CMS_decrypt(3SSL)						      OpenSSL							 CMS_decrypt(3SSL)

NAME
CMS_decrypt - decrypt content from a CMS envelopedData structure SYNOPSIS
#include <openssl/cms.h> int CMS_decrypt(CMS_ContentInfo *cms, EVP_PKEY *pkey, X509 *cert, BIO *dcont, BIO *out, unsigned int flags); DESCRIPTION
CMS_decrypt() extracts and decrypts the content from a CMS EnvelopedData structure. pkey is the private key of the recipient, cert is the recipient's certificate, out is a BIO to write the content to and flags is an optional set of flags. The dcont parameter is used in the rare case where the encrypted content is detached. It will normally be set to NULL. NOTES
OpenSSL_add_all_algorithms() (or equivalent) should be called before using this function or errors about unknown algorithms will occur. Although the recipients certificate is not needed to decrypt the data it is needed to locate the appropriate (of possible several) recipients in the CMS structure. If cert is set to NULL all possible recipients are tried. It is possible to determine the correct recipient key by other means (for example looking them up in a database) and setting them in the CMS structure in advance using the CMS utility functions such as CMS_set1_pkey(). In this case both cert and pkey should be set to NULL. To process KEKRecipientInfo types CMS_set1_key() or CMS_RecipientInfo_set0_key() and CMS_ReceipientInfo_decrypt() should be called before CMS_decrypt() and cert and pkey set to NULL. The following flags can be passed in the flags parameter. If the CMS_TEXT flag is set MIME headers for type text/plain are deleted from the content. If the content is not of type text/plain then an error is returned. RETURN VALUES
CMS_decrypt() returns either 1 for success or 0 for failure. The error can be obtained from ERR_get_error(3) BUGS
The lack of single pass processing and the need to hold all data in memory as mentioned in CMS_verify() also applies to CMS_decrypt(). SEE ALSO
ERR_get_error(3), CMS_encrypt(3) HISTORY
CMS_decrypt() was added to OpenSSL 0.9.8 1.0.1e 2013-02-11 CMS_decrypt(3SSL)

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CMS_encrypt(3SSL)						      OpenSSL							 CMS_encrypt(3SSL)

NAME
CMS_encrypt - create a CMS envelopedData structure SYNOPSIS
#include <openssl/cms.h> CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, unsigned int flags); DESCRIPTION
CMS_encrypt() creates and returns a CMS EnvelopedData structure. certs 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. NOTES
Only certificates carrying RSA keys are supported so the recipient certificates supplied to this function must all contain RSA public keys, though they do not have to be signed using the RSA algorithm. EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use because most clients will support it. The algorithm passed in the cipher parameter must support ASN1 encoding of its parameters. Many browsers implement a "sign and encrypt" 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 BIO and passing it to CMS_encrypt(). The following flags can be passed in the flags parameter. If the CMS_TEXT flag is set MIME headers for type text/plain are prepended to the data. Normally the supplied content is translated into MIME canonical format (as required by the S/MIME specifications) if CMS_BINARY 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 CMS_BINARY is set then CMS_TEXT is ignored. OpenSSL will by default identify recipient certificates using issuer name and serial number. If CMS_USE_KEYID 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. If the CMS_STREAM flag is set a partial CMS_ContentInfo structure is returned suitable for streaming I/O: no data is read from the BIO in. If the CMS_PARTIAL flag is set a partial CMS_ContentInfo structure is returned to which additional recipients and attributes can be added before finalization. The data being encrypted is included in the CMS_ContentInfo structure, unless CMS_DETACHED is set in which case it is omitted. This is rarely used in practice and is not supported by SMIME_write_CMS(). NOTES
If the flag CMS_STREAM is set the returned CMS_ContentInfo structure is not complete and outputting its contents via a function that does not properly finalize the CMS_ContentInfo structure will give unpredictable results. Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(), PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization can be performed by obtaining the streaming ASN1 BIO directly using BIO_new_CMS(). The recipients specified in certs use a CMS KeyTransRecipientInfo info structure. KEKRecipientInfo is also supported using the flag CMS_PARTIAL and CMS_add0_recipient_key(). The parameter certs may be NULL if CMS_PARTIAL is set and recipients added later using CMS_add1_recipient_cert() or CMS_add0_recipient_key(). RETURN VALUES
CMS_encrypt() returns either a CMS_ContentInfo structure or NULL if an error occurred. The error can be obtained from ERR_get_error(3). SEE ALSO
ERR_get_error(3), CMS_decrypt(3) HISTORY
CMS_decrypt() was added to OpenSSL 0.9.8 The CMS_STREAM flag was first supported in OpenSSL 1.0.0. 1.0.1e 2013-02-11 CMS_encrypt(3SSL)
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