SYNOPSIS

        #include <openssl/evp.h>

        int EVP_SealInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                         unsigned char **ek, int *ekl, unsigned char *iv,
                         EVP_PKEY **pubk, int npubk);
        int EVP_SealUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                int *outl, unsigned char *in, int inl);
        int EVP_SealFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
                int *outl);

DESCRIPTION

       The EVP envelope routines are a high level interface to envelope
       encryption. They generate a random key and IV (if required) then "enve-
       lope" it by using public key encryption. Data can then be encrypted
       using this key.

       EVP_SealInit() initializes a cipher context ctx for encryption with
       cipher type using a random secret key and IV. type is normally supplied
       by a function such as EVP_des_cbc(). The secret key is encrypted using
       one or more public keys, this allows the same encrypted data to be
       decrypted using any of the corresponding private keys. ek is an array
       of buffers where the public key encrypted secret key will be written,
       each buffer must contain enough room for the corresponding encrypted
       key: that is ek[i] must have room for EVP_PKEY_size(pubk[i]) bytes. The
       actual size of each encrypted secret key is written to the array ekl.
       pubk is an array of npubk public keys.

       The iv parameter is a buffer where the generated IV is written to. It
       must contain enough room for the corresponding cipher's IV, as deter-
       mined by (for example) EVP_CIPHER_iv_length(type).

       If the cipher does not require an IV then the iv parameter is ignored
       and can be NULL.

       EVP_SealUpdate() and EVP_SealFinal() have exactly the same properties
       as the EVP_EncryptUpdate() and EVP_EncryptFinal() routines, as docu-
       mented on the EVP_EncryptInit(3) manual page.

RETURN VALUES

       EVP_SealInit() returns 0 on error or npubk if successful.

       EVP_SealUpdate() and EVP_SealFinal() return 1 for success and 0 for
       failure.

NOTES

       Because a random secret key is generated the random number generator
       must be seeded before calling EVP_SealInit().

       The public key must be RSA because it is the only OpenSSL public key
       algorithm that supports key transport.

HISTORY

       EVP_SealFinal() did not return a value before OpenSSL 0.9.7.



0.9.8d                            2005-03-29                   EVP_SealInit(3)