Manual Pages for UNIX Operating System command usage for man EVP_SealUpdate

OpenSSL                                    EVP_SealInit(3openssl)



NNNNAAAAMMMMEEEE
     EVP_SealInit, EVP_SealUpdate, EVP_SealFinal - EVP envelope
     encryption

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      #include 

      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);


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

     EVP_SealInit() initializes a cipher context ccccttttxxxx for
     encryption with cipher ttttyyyyppppeeee using a random secret key and
     IV. ttttyyyyppppeeee 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. eeeekkkk 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 eeeekkkk[[[[iiii]]]] must have
     room for EEEEVVVVPPPP_PPPPKKKKEEEEYYYY_ssssiiiizzzzeeee((((ppppuuuubbbbkkkk[[[[iiii]]]])))) bytes. The actual size of
     each encrypted secret key is written to the array eeeekkkkllll. ppppuuuubbbbkkkk
     is an array of nnnnppppuuuubbbbkkkk public keys.

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

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

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

RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEESSSS
     EVP_SealInit() returns 0 on error or nnnnppppuuuubbbbkkkk if successful.





29/Mar/2005            Last change: 0.9.8o                      1






OpenSSL                                    EVP_SealInit(3openssl)



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

NNNNOOOOTTTTEEEESSSS
     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.

     Envelope encryption is the usual method of using public key
     encryption on large amounts of data, this is because public
     key encryption is slow but symmetric encryption is fast. So
     symmetric encryption is used for bulk encryption and the
     small random symmetric key used is transferred using public
     key encryption.

     It is possible to call EVP_SealInit() twice in the same way
     as EVP_EncryptInit(). The first call should have nnnnppppuuuubbbbkkkk set
     to 0 and (after setting any cipher parameters) it should be
     called again with ttttyyyyppppeeee set to NULL.

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     evp(3), rand(3), EVP_EncryptInit(3), EVP_OpenInit(3)

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




























29/Mar/2005            Last change: 0.9.8o                      2