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Diffstat (limited to 'lib/libssl/src/doc/crypto/EVP_SealInit.pod')
-rw-r--r-- | lib/libssl/src/doc/crypto/EVP_SealInit.pod | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/lib/libssl/src/doc/crypto/EVP_SealInit.pod b/lib/libssl/src/doc/crypto/EVP_SealInit.pod new file mode 100644 index 00000000000..1579d110fa2 --- /dev/null +++ b/lib/libssl/src/doc/crypto/EVP_SealInit.pod @@ -0,0 +1,70 @@ +=pod + +=head1 NAME + +EVP_SealInit, EVP_SealUpdate, EVP_SealFinal - EVP envelope encryption + +=head1 SYNOPSIS + + #include <openssl/evp.h> + + int EVP_SealInit(EVP_CIPHER_CTX *ctx, EVP_CIPHER *type, unsigned char **ek, + int *ekl, unsigned char *iv,EVP_PKEY **pubk, int npubk); + void EVP_SealUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, + int *outl, unsigned char *in, int inl); + void EVP_SealFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, + int *outl); + +=head1 DESCRIPTION + +The EVP envelope routines are a high level interface to envelope +encryption. They generate a random key and then "envelope" it by +using public key encryption. Data can then be encrypted using this +key. + +EVP_SealInit() initialises a cipher context B<ctx> for encryption +with cipher B<type> using a random secret key and IV supplied in +the B<iv> parameter. B<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. B<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 +B<ek[i]> must have room for B<EVP_PKEY_size(pubk[i])> bytes. The actual +size of each encrypted secret key is written to the array B<ekl>. B<pubk> is +an array of B<npubk> public keys. + +EVP_SealUpdate() and EVP_SealFinal() have exactly the same properties +as the EVP_EncryptUpdate() and EVP_EncryptFinal() routines, as +documented on the L<EVP_EncryptInit(3)|EVP_EncryptInit(3)> manual +page. + +=head1 RETURN VALUES + +EVP_SealInit() returns -1 on error or B<npubk> if successful. + +EVP_SealUpdate() and EVP_SealFinal() do not return values. + +=head1 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. + +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. + +=head1 SEE ALSO + +L<evp(3)|evp(3)>,L<rand(3)|rand(3)> +L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>, +L<EVP_OpenInit(3)|EVP_OpenInit(3)> + +=head1 HISTORY + +=cut |