1=pod 2 3=head1 NAME 4 5EVP_OpenInit, EVP_OpenUpdate, EVP_OpenFinal - EVP envelope decryption 6 7=head1 SYNOPSIS 8 9 #include <openssl/evp.h> 10 11 int EVP_OpenInit(EVP_CIPHER_CTX *ctx,EVP_CIPHER *type,unsigned char *ek, 12 int ekl,unsigned char *iv,EVP_PKEY *priv); 13 int EVP_OpenUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, 14 int *outl, unsigned char *in, int inl); 15 int EVP_OpenFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, 16 int *outl); 17 18=head1 DESCRIPTION 19 20The EVP envelope routines are a high level interface to envelope 21decryption. They decrypt a public key encrypted symmetric key and 22then decrypt data using it. 23 24EVP_OpenInit() initializes a cipher context B<ctx> for decryption 25with cipher B<type>. It decrypts the encrypted symmetric key of length 26B<ekl> bytes passed in the B<ek> parameter using the private key B<priv>. 27The IV is supplied in the B<iv> parameter. 28 29EVP_OpenUpdate() and EVP_OpenFinal() have exactly the same properties 30as the EVP_DecryptUpdate() and EVP_DecryptFinal() routines, as 31documented on the L<EVP_EncryptInit(3)|EVP_EncryptInit(3)> manual 32page. 33 34=head1 NOTES 35 36It is possible to call EVP_OpenInit() twice in the same way as 37EVP_DecryptInit(). The first call should have B<priv> set to NULL 38and (after setting any cipher parameters) it should be called again 39with B<type> set to NULL. 40 41If the cipher passed in the B<type> parameter is a variable length 42cipher then the key length will be set to the value of the recovered 43key length. If the cipher is a fixed length cipher then the recovered 44key length must match the fixed cipher length. 45 46=head1 RETURN VALUES 47 48EVP_OpenInit() returns 0 on error or a non zero integer (actually the 49recovered secret key size) if successful. 50 51EVP_OpenUpdate() returns 1 for success or 0 for failure. 52 53EVP_OpenFinal() returns 0 if the decrypt failed or 1 for success. 54 55=head1 SEE ALSO 56 57L<evp(3)|evp(3)>, L<rand(3)|rand(3)>, 58L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>, 59L<EVP_SealInit(3)|EVP_SealInit(3)> 60 61=head1 HISTORY 62 63=cut 64