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## EVP_SealInit(3)
## NAMEEVP_SealInit, EVP_SealUpdate, EVP_SealFinal - EVP envelope encryption
## 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);
## DESCRIPTIONThe 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.
The
If the cipher does not require an IV then the
## RETURN VALUES
## NOTES
Because a random secret key is generated the random number generator must
be seeded before calling 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
## SEE ALSOevp(3), rand(3), EVP_EncryptInit(3), EVP_OpenInit(3)
## HISTORY
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