Manual pages for EVP_Open* and EVP_Seal*

doc/crypto/EVP_OpenInit.pod

+=pod
+
+=head1 NAME
+
+EVP_OpenInit, EVP_OpenUpdate, EVP_OpenFinal - EVP envelope decryption
+
+=head1 SYNOPSIS
+
+ #include <openssl/evp.h>
+
+ int EVP_OpenInit(EVP_CIPHER_CTX *ctx,EVP_CIPHER *type,unsigned char *ek,
+		int ekl,unsigned char *iv,EVP_PKEY *priv);
+ void EVP_OpenUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
+         int *outl, unsigned char *in, int inl);
+ void EVP_OpenFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
+         int *outl);
+
+=head1 DESCRIPTION
+
+The EVP envelope routines are a high level interface to envelope
+decryption. They decrypt a public key encrypted symmetric key and
+then decrypt data using it.
+
+EVP_OpenInit() initialises a cipher context B<ctx> for decryption
+with cipher B<type>. It decrypts the encrypted symmetric key of length
+B<ekl> bytes passed in the B<ek> parameter using the private key B<priv>.
+The IV is supplied in the B<iv> parameter.
+
+EVP_OpenUpdate() and EVP_OpenFinal() have exactly the same properties
+as the EVP_DecryptUpdate() and EVP_DecryptFinal() routines, as 
+documented on the L<EVP_EncryptInit(3)|EVP_EncryptInit(3)> manual
+page. 
+
+=head1 RETURN VALUES
+
+EVP_OpenInit() returns -1 on error or an non zero integer (actually the
+recovered secret key size) if successful.
+
+EVP_SealUpdate() does not return a value.
+
+EVP_SealFinal() returns 0 if the decrypt failed or 1 for success.
+
+=head1 SEE ALSO
+
+L<evp(3)|evp(3)>,L<rand(3)|rand(3)>
+L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>,
+L<EVP_SealInit(3)|EVP_SealInit(3)>
+
+=head1 HISTORY
+
+=cut

doc/crypto/EVP_SealInit.pod

+=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