NAME
EVP_CIPHER_CTX_init,
EVP_CIPHER_CTX_cleanup,
EVP_Cipher —
obsolete EVP cipher
functions
SYNOPSIS
#include
<openssl/evp.h>
void
EVP_CIPHER_CTX_init(EVP_CIPHER_CTX
*ctx);
int
EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX
*ctx);
int
EVP_Cipher(EVP_CIPHER_CTX *ctx,
unsigned char *out, const unsigned
char *in, unsigned int in_len);
DESCRIPTION
EVP_CIPHER_CTX_init()
is a deprecated function that could be used to clear a cipher context on the
stack before EVP_CIPHER_CTX was made opaque. Calling
it on a cipher context just returned from
EVP_CIPHER_CTX_new(3) has no effect. Calling it on a cipher
context that was already used leaks memory. Instead, use
EVP_CIPHER_CTX_reset(3) or
EVP_CIPHER_CTX_free(3).
EVP_CIPHER_CTX_cleanup()
is a deprecated alias for
EVP_CIPHER_CTX_reset(3). It clears all information from
ctx and frees all allocated memory associated with it,
except the ctx object itself.
EVP_Cipher()
exposes implementation details of the functions
EVP_CipherUpdate(3) and
EVP_CipherFinal(3) that should never have become part of the
public API.
If the flag EVP_CIPH_FLAG_CUSTOM_CIPHER is
set for the cipher used by ctx, behaviour depends on
in. If that argument is NULL
and in_len is 0, behaviour is similar to
EVP_CipherFinal(3); if in_len is not 0,
behaviour is undefined. If in is not
NULL, behaviour is similar to
EVP_CipherUpdate(3). In both cases, the exceptions to the
similarity are that arguments and return values differ.
If the flag
EVP_CIPH_FLAG_CUSTOM_CIPHER is not set for the
cipher used by ctx, it encrypts or decrypts aligned
blocks of data whose lengths match the cipher block size. It requires that
the previous encryption or decryption operation using the same
ctx, if there was any, ended exactly on a block
boundary and that in_len is an integer multiple of the
cipher block size. If either of these conditions is violated,
EVP_Cipher()
silently produces incorrect results. For that reason, using the function
EVP_CipherUpdate(3) instead is strongly recommended. The
latter can safely handle partial blocks, and even if
in_len actually is a multiple of the cipher block size
for all calls, the overhead incurred by using
EVP_CipherUpdate(3) is minimal.
RETURN VALUES
EVP_CIPHER_CTX_cleanup() returns 1 for
success or 0 for failure.
With EVP_CIPH_FLAG_CUSTOM_CIPHER,
EVP_Cipher() returns the number of bytes written to
out for success or -1 for failure. Without
EVP_CIPH_FLAG_CUSTOM_CIPHER, it returns 1 for
success or 0 for failure.
SEE ALSO
HISTORY
EVP_Cipher() first appeared in SSLeay
0.6.5. EVP_CIPHER_CTX_cleanup() first appeared in
SSLeay 0.8.0. EVP_CIPHER_CTX_init() first appeared
in SSLeay 0.9.0. All these functions have been available since
OpenBSD 2.4.
CAVEATS
Checking the return value of EVP_Cipher()
requires unusual caution: zero signals success if
EVP_CIPH_FLAG_CUSTOM_CIPHER is set or failure
otherwise.