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BIO_f_cipher(3)
NAME
  BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx -
  Cipher BIO filter

SYNOPSIS
  #include <openssl/bio.h>
  #include <openssl/evp.h>

  BIO_METHOD *	   BIO_f_cipher(
	  void );

  void BIO_set_cipher(
	  BIO *b,
	  const EVP_CIPHER *cipher,
	  unsigned char *key,
	  unsigned char *iv,
	  int enc );

  int BIO_get_cipher_status(
	  BIO *b );

  int BIO_get_cipher_ctx(
	  BIO *b,
	  EVP_CIPHER_CTX **pctx );

DESCRIPTION
  The BIO_f_cipher() function returns the cipher BIO method. This is a filter
  BIO that encrypts any data written through it, and decrypts any data read
  from it. It is a BIO wrapper for the EVP_CipherInit(), EVP_CipherUpdate(),
  and EVP_CipherFinal() cipher functions .

  Cipher BIOs do not support BIO_gets() or BIO_puts().

  The BIO_flush() function on an encryption BIO that is being written through
  is used to signal that no more data is to be encrypted.  This is used to
  flush and possibly pad the final block through the BIO.

  The BIO_set_cipher() function sets the cipher of BIO b to cipher using key
  and iv. The enc should be set to 1 for encryption and zero for decryption.

  When reading from an encryption BIO the final block is automatically
  decrypted and checked when EOF is detected. The BIO_get_cipher_status()
  function is a BIO_ctrl() macro which can be called to determine whether the
  decryption operation was successful.

  The BIO_get_cipher_ctx() function is a BIO_ctrl() macro which retrieves the
  internal BIO cipher context.	The retrieved context can be used in
  conjunction with the standard cipher routines to set it up. This is useful
  when BIO_set_cipher() is not flexible enough for the applications needs.

NOTES
  When encrypting, BIO_flush() must be called to flush the final block
  through the BIO. Otherwise, the final block will fail a subsequent decrypt.

  When decrypting, an error on the final block is signalled by a zero return
  value from the read operation. A successful decrypt followed by EOF will
  also return zero for the final read. The BIO_get_cipher_status() function
  should be called to determine if the decrypt was successful.

  If BIO_gets() or BIO_puts() support is needed then it can be achieved by
  preceding the cipher BIO with a buffering BIO.

RETURN VALUES
  BIO_f_cipher() returns the cipher BIO method.

  BIO_set_cipher() does not return a value.

  BIO_get_cipher_status() returns 1 for a successful decrypt and 0 for
  failure.

  BIO_get_cipher_ctx() always returns 1.

SEE ALSO
  TBA

Index for Section 3

Alphabetical listing for B

Top of page