932 lines
42 KiB
Groff
Executable File
932 lines
42 KiB
Groff
Executable File
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.\" ========================================================================
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.\"
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.IX Title "EVP_ENCRYPTINIT 3"
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.TH EVP_ENCRYPTINIT 3 "2020-03-02" "3.0.0-dev" "OpenSSL"
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.\" For nroff, turn off justification. Always turn off hyphenation; it makes
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.\" way too many mistakes in technical documents.
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.if n .ad l
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.nh
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.SH "NAME"
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EVP_CIPHER_fetch,
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EVP_CIPHER_up_ref,
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EVP_CIPHER_free,
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|
EVP_CIPHER_CTX_new,
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EVP_CIPHER_CTX_reset,
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EVP_CIPHER_CTX_free,
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EVP_EncryptInit_ex,
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EVP_EncryptUpdate,
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EVP_EncryptFinal_ex,
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EVP_DecryptInit_ex,
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EVP_DecryptUpdate,
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EVP_DecryptFinal_ex,
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|
EVP_CipherInit_ex,
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EVP_CipherUpdate,
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|
EVP_CipherFinal_ex,
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|
EVP_CIPHER_CTX_set_key_length,
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|
EVP_CIPHER_CTX_ctrl,
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|
EVP_EncryptInit,
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|
EVP_EncryptFinal,
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|
EVP_DecryptInit,
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|
EVP_DecryptFinal,
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|
EVP_CipherInit,
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EVP_CipherFinal,
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EVP_Cipher,
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|
EVP_get_cipherbyname,
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|
EVP_get_cipherbynid,
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|
EVP_get_cipherbyobj,
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EVP_CIPHER_is_a,
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|
EVP_CIPHER_name,
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|
EVP_CIPHER_number,
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|
EVP_CIPHER_names_do_all,
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|
EVP_CIPHER_provider,
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|
EVP_CIPHER_nid,
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|
EVP_CIPHER_get_params,
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|
EVP_CIPHER_gettable_params,
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|
EVP_CIPHER_block_size,
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|
EVP_CIPHER_key_length,
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|
EVP_CIPHER_iv_length,
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|
EVP_CIPHER_flags,
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|
EVP_CIPHER_mode,
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|
EVP_CIPHER_type,
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|
EVP_CIPHER_CTX_cipher,
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|
EVP_CIPHER_CTX_name,
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|
EVP_CIPHER_CTX_nid,
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|
EVP_CIPHER_CTX_get_params,
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|
EVP_CIPHER_gettable_ctx_params,
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|
EVP_CIPHER_CTX_set_params,
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|
EVP_CIPHER_settable_ctx_params,
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|
EVP_CIPHER_CTX_block_size,
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|
EVP_CIPHER_CTX_key_length,
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|
EVP_CIPHER_CTX_iv_length,
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|
EVP_CIPHER_CTX_tag_length,
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|
EVP_CIPHER_CTX_get_app_data,
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|
EVP_CIPHER_CTX_set_app_data,
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|
EVP_CIPHER_CTX_type,
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|
EVP_CIPHER_CTX_flags,
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|
EVP_CIPHER_CTX_mode,
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|
EVP_CIPHER_param_to_asn1,
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|
EVP_CIPHER_asn1_to_param,
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|
EVP_CIPHER_CTX_set_padding,
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|
EVP_enc_null,
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|
EVP_CIPHER_do_all_provided
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|
\&\- EVP cipher routines
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|
.SH "SYNOPSIS"
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|
.IX Header "SYNOPSIS"
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|
.Vb 1
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|
\& #include <openssl/evp.h>
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|
\&
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|
\& EVP_CIPHER *EVP_CIPHER_fetch(OPENSSL_CTX *ctx, const char *algorithm,
|
|
\& const char *properties);
|
|
\& int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
|
|
\& void EVP_CIPHER_free(EVP_CIPHER *cipher);
|
|
\& EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
|
|
\& int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
|
|
\& void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
|
|
\&
|
|
\& int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& ENGINE *impl, const unsigned char *key, const unsigned char *iv);
|
|
\& int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& int *outl, const unsigned char *in, int inl);
|
|
\& int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
|
|
\&
|
|
\& int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& ENGINE *impl, const unsigned char *key, const unsigned char *iv);
|
|
\& int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& int *outl, const unsigned char *in, int inl);
|
|
\& int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
|
|
\&
|
|
\& int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
|
|
\& int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& int *outl, const unsigned char *in, int inl);
|
|
\& int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
|
|
\&
|
|
\& int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& const unsigned char *key, const unsigned char *iv);
|
|
\& int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
|
|
\&
|
|
\& int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& const unsigned char *key, const unsigned char *iv);
|
|
\& int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
|
|
\&
|
|
\& int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& const unsigned char *key, const unsigned char *iv, int enc);
|
|
\& int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
|
|
\&
|
|
\& int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& const unsigned char *in, unsigned int inl);
|
|
\&
|
|
\& int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
|
|
\& int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
|
|
\& int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
|
|
\& int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
|
|
\&
|
|
\& const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
|
|
\& const EVP_CIPHER *EVP_get_cipherbynid(int nid);
|
|
\& const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
|
|
\&
|
|
\& int EVP_CIPHER_nid(const EVP_CIPHER *e);
|
|
\& int EVP_CIPHER_number(const EVP_CIPHER *e);
|
|
\& int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
|
|
\& void EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher,
|
|
\& void (*fn)(const char *name, void *data),
|
|
\& void *data);
|
|
\& const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
|
|
\& const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
|
|
\& int EVP_CIPHER_block_size(const EVP_CIPHER *e);
|
|
\& int EVP_CIPHER_key_length(const EVP_CIPHER *e);
|
|
\& int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
|
|
\& unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
|
|
\& unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
|
|
\& int EVP_CIPHER_type(const EVP_CIPHER *ctx);
|
|
\&
|
|
\& const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
|
|
\& int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
|
|
\& const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
|
|
\&
|
|
\& int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
|
|
\& int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
|
|
\& int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
|
|
\& const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
|
|
\& const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
|
|
\& const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
|
|
\& int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
|
|
\& int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
|
|
\& int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
|
|
\& int EVP_CIPHER_CTX_tag_length(const EVP_CIPHER_CTX *ctx);
|
|
\& void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
|
|
\& void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
|
|
\& int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
|
|
\& int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
|
|
\&
|
|
\& int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
|
|
\& int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
|
|
\&
|
|
\& void EVP_CIPHER_do_all_provided(OPENSSL_CTX *libctx,
|
|
\& void (*fn)(EVP_CIPHER *cipher, void *arg),
|
|
\& void *arg);
|
|
.Ve
|
|
.SH "DESCRIPTION"
|
|
.IX Header "DESCRIPTION"
|
|
The \s-1EVP\s0 cipher routines are a high level interface to certain
|
|
symmetric ciphers.
|
|
.PP
|
|
The \fB\s-1EVP_CIPHER\s0\fR type is a structure for cipher method implementation.
|
|
.PP
|
|
\&\fIEVP_CIPHER_fetch()\fR fetches the cipher implementation for the given
|
|
\&\fBalgorithm\fR from any provider offering it, within the criteria given
|
|
by the \fBproperties\fR.
|
|
See \*(L"Fetching algorithms\*(R" in \fIprovider\fR\|(7) for further information.
|
|
.PP
|
|
The returned value must eventually be freed with \fIEVP_CIPHER_free()\fR.
|
|
.PP
|
|
\&\fIEVP_CIPHER_up_ref()\fR increments the reference count for an \fB\s-1EVP_CIPHER\s0\fR
|
|
structure.
|
|
.PP
|
|
\&\fIEVP_CIPHER_free()\fR decrements the reference count for the \fB\s-1EVP_CIPHER\s0\fR
|
|
structure.
|
|
If the reference count drops to 0 then the structure is freed.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_new()\fR creates a cipher context.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_free()\fR clears all information from a cipher context
|
|
and free up any allocated memory associate with it, including \fBctx\fR
|
|
itself. This function should be called after all operations using a
|
|
cipher are complete so sensitive information does not remain in
|
|
memory.
|
|
.PP
|
|
\&\fIEVP_EncryptInit_ex()\fR sets up cipher context \fBctx\fR for encryption
|
|
with cipher \fBtype\fR. \fBtype\fR is typically supplied by a function such
|
|
as \fIEVP_aes_256_cbc()\fR, or a value explicitly fetched with
|
|
\&\fIEVP_CIPHER_fetch()\fR. If \fBimpl\fR is non-NULL, its implementation of the
|
|
cipher \fBtype\fR is used if there is one, and if not, the default
|
|
implementation is used. \fBkey\fR is the symmetric key to use
|
|
and \fBiv\fR is the \s-1IV\s0 to use (if necessary), the actual number of bytes
|
|
used for the key and \s-1IV\s0 depends on the cipher. It is possible to set
|
|
all parameters to \s-1NULL\s0 except \fBtype\fR in an initial call and supply
|
|
the remaining parameters in subsequent calls, all of which have \fBtype\fR
|
|
set to \s-1NULL\s0. This is done when the default cipher parameters are not
|
|
appropriate.
|
|
For \s-1EVP_CIPH_GCM_MODE\s0 the \s-1IV\s0 will be generated internally if it is not
|
|
specified.
|
|
.PP
|
|
\&\fIEVP_EncryptUpdate()\fR encrypts \fBinl\fR bytes from the buffer \fBin\fR and
|
|
writes the encrypted version to \fBout\fR. This function can be called
|
|
multiple times to encrypt successive blocks of data. The amount
|
|
of data written depends on the block alignment of the encrypted data:
|
|
as a result the amount of data written may be anything from zero bytes
|
|
to (inl + cipher_block_size \- 1) so \fBout\fR should contain sufficient
|
|
room. The actual number of bytes written is placed in \fBoutl\fR. It also
|
|
checks if \fBin\fR and \fBout\fR are partially overlapping, and if they are
|
|
0 is returned to indicate failure.
|
|
.PP
|
|
If padding is enabled (the default) then \fIEVP_EncryptFinal_ex()\fR encrypts
|
|
the \*(L"final\*(R" data, that is any data that remains in a partial block.
|
|
It uses standard block padding (aka \s-1PKCS\s0 padding) as described in
|
|
the \s-1NOTES\s0 section, below. The encrypted
|
|
final data is written to \fBout\fR which should have sufficient space for
|
|
one cipher block. The number of bytes written is placed in \fBoutl\fR. After
|
|
this function is called the encryption operation is finished and no further
|
|
calls to \fIEVP_EncryptUpdate()\fR should be made.
|
|
.PP
|
|
If padding is disabled then \fIEVP_EncryptFinal_ex()\fR will not encrypt any more
|
|
data and it will return an error if any data remains in a partial block:
|
|
that is if the total data length is not a multiple of the block size.
|
|
.PP
|
|
\&\fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptUpdate()\fR and \fIEVP_DecryptFinal_ex()\fR are the
|
|
corresponding decryption operations. \fIEVP_DecryptFinal()\fR will return an
|
|
error code if padding is enabled and the final block is not correctly
|
|
formatted. The parameters and restrictions are identical to the encryption
|
|
operations except that if padding is enabled the decrypted data buffer \fBout\fR
|
|
passed to \fIEVP_DecryptUpdate()\fR should have sufficient room for
|
|
(\fBinl\fR + cipher_block_size) bytes unless the cipher block size is 1 in
|
|
which case \fBinl\fR bytes is sufficient.
|
|
.PP
|
|
\&\fIEVP_CipherInit_ex()\fR, \fIEVP_CipherUpdate()\fR and \fIEVP_CipherFinal_ex()\fR are
|
|
functions that can be used for decryption or encryption. The operation
|
|
performed depends on the value of the \fBenc\fR parameter. It should be set
|
|
to 1 for encryption, 0 for decryption and \-1 to leave the value unchanged
|
|
(the actual value of 'enc' being supplied in a previous call).
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_reset()\fR clears all information from a cipher context
|
|
and free up any allocated memory associate with it, except the \fBctx\fR
|
|
itself. This function should be called anytime \fBctx\fR is to be reused
|
|
for another \fIEVP_CipherInit()\fR / \fIEVP_CipherUpdate()\fR / \fIEVP_CipherFinal()\fR
|
|
series of calls.
|
|
.PP
|
|
\&\fIEVP_EncryptInit()\fR, \fIEVP_DecryptInit()\fR and \fIEVP_CipherInit()\fR behave in a
|
|
similar way to \fIEVP_EncryptInit_ex()\fR, \fIEVP_DecryptInit_ex()\fR and
|
|
\&\fIEVP_CipherInit_ex()\fR except they always use the default cipher implementation.
|
|
.PP
|
|
\&\fIEVP_EncryptFinal()\fR, \fIEVP_DecryptFinal()\fR and \fIEVP_CipherFinal()\fR are
|
|
identical to \fIEVP_EncryptFinal_ex()\fR, \fIEVP_DecryptFinal_ex()\fR and
|
|
\&\fIEVP_CipherFinal_ex()\fR. In previous releases they also cleaned up
|
|
the \fBctx\fR, but this is no longer done and \fIEVP_CIPHER_CTX_clean()\fR
|
|
must be called to free any context resources.
|
|
.PP
|
|
\&\fIEVP_Cipher()\fR encrypts or decrypts a maximum \fIinl\fR amount of bytes from
|
|
\&\fIin\fR and leaves the result in \fIout\fR.
|
|
If the cipher doesn't have the flag \fB\s-1EVP_CIPH_FLAG_CUSTOM_CIPHER\s0\fR set,
|
|
then \fIinl\fR must be a multiple of \fIEVP_CIPHER_block_size()\fR. If it isn't,
|
|
the result is undefined. If the cipher has that flag set, then \fIinl\fR
|
|
can be any size.
|
|
This function is historic and shouldn't be used in an application, please
|
|
consider using \fIEVP_CipherUpdate()\fR and EVP_CipherFinal_ex instead.
|
|
.PP
|
|
\&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
|
|
return an \s-1EVP_CIPHER\s0 structure when passed a cipher name, a \s-1NID\s0 or an
|
|
\&\s-1ASN1_OBJECT\s0 structure.
|
|
.PP
|
|
\&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return the \s-1NID\s0 of a cipher when
|
|
passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR structure. The actual \s-1NID\s0
|
|
value is an internal value which may not have a corresponding \s-1OBJECT\s0
|
|
\&\s-1IDENTIFIER\s0.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_set_padding()\fR enables or disables padding. This
|
|
function should be called after the context is set up for encryption
|
|
or decryption with \fIEVP_EncryptInit_ex()\fR, \fIEVP_DecryptInit_ex()\fR or
|
|
\&\fIEVP_CipherInit_ex()\fR. By default encryption operations are padded using
|
|
standard block padding and the padding is checked and removed when
|
|
decrypting. If the \fBpad\fR parameter is zero then no padding is
|
|
performed, the total amount of data encrypted or decrypted must then
|
|
be a multiple of the block size or an error will occur.
|
|
.PP
|
|
\&\fIEVP_CIPHER_get_params()\fR retrieves the requested list of algorithm
|
|
\&\fBparams\fR from a \fBcipher\fR.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_set_params()\fR Sets the list of operation \fBparams\fR into a \s-1CIPHER\s0
|
|
context \fBctx\fR.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_get_params()\fR retrieves the requested list of operation
|
|
\&\fBparams\fR from \s-1CIPHER\s0 context \fBctx\fR.
|
|
.PP
|
|
\&\fIEVP_CIPHER_gettable_params()\fR, \fIEVP_CIPHER_gettable_ctx_params()\fR, and
|
|
\&\fIEVP_CIPHER_settable_ctx_params()\fR get a constant \fB\s-1OSSL_PARAM\s0\fR array
|
|
that describes the retrievable and settable parameters, i.e. parameters
|
|
that can be used with \fIEVP_CIPHER_get_params()\fR, \fIEVP_CIPHER_CTX_get_params()\fR
|
|
and \fIEVP_CIPHER_CTX_set_params()\fR, respectively.
|
|
See \s-1\fIOSSL_PARAM\s0\fR\|(3) for the use of \fB\s-1OSSL_PARAM\s0\fR as parameter descriptor.
|
|
.PP
|
|
\&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
|
|
length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
|
|
structure. The constant \fB\s-1EVP_MAX_KEY_LENGTH\s0\fR is the maximum key length
|
|
for all ciphers. Note: although \fIEVP_CIPHER_key_length()\fR is fixed for a
|
|
given cipher, the value of \fIEVP_CIPHER_CTX_key_length()\fR may be different
|
|
for variable key length ciphers.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_set_key_length()\fR sets the key length of the cipher ctx.
|
|
If the cipher is a fixed length cipher then attempting to set the key
|
|
length to any value other than the fixed value is an error.
|
|
.PP
|
|
\&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
|
|
length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR.
|
|
It will return zero if the cipher does not use an \s-1IV\s0. The constant
|
|
\&\fB\s-1EVP_MAX_IV_LENGTH\s0\fR is the maximum \s-1IV\s0 length for all ciphers.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_tag_length()\fR returns the tag length of a \s-1AEAD\s0 cipher when passed
|
|
a \fB\s-1EVP_CIPHER_CTX\s0\fR. It will return zero if the cipher does not support a tag.
|
|
It returns a default value if the tag length has not been set.
|
|
.PP
|
|
\&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
|
|
size of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
|
|
structure. The constant \fB\s-1EVP_MAX_BLOCK_LENGTH\s0\fR is also the maximum block
|
|
length for all ciphers.
|
|
.PP
|
|
\&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the type of the passed
|
|
cipher or context. This \*(L"type\*(R" is the actual \s-1NID\s0 of the cipher \s-1OBJECT\s0
|
|
\&\s-1IDENTIFIER\s0 as such it ignores the cipher parameters and 40 bit \s-1RC2\s0 and
|
|
128 bit \s-1RC2\s0 have the same \s-1NID\s0. If the cipher does not have an object
|
|
identifier or does not have \s-1ASN1\s0 support this function will return
|
|
\&\fBNID_undef\fR.
|
|
.PP
|
|
\&\fIEVP_CIPHER_is_a()\fR returns 1 if \fIcipher\fR is an implementation of an
|
|
algorithm that's identifiable with \fIname\fR, otherwise 0.
|
|
If \fIcipher\fR is a legacy cipher (it's the return value from the likes
|
|
of \fIEVP_aes128()\fR rather than the result of an \fIEVP_CIPHER_fetch()\fR), only
|
|
cipher names registered with the default library context (see
|
|
\&\s-1\fIOPENSSL_CTX\s0\fR\|(3)) will be considered.
|
|
.PP
|
|
\&\fIEVP_CIPHER_number()\fR returns the internal dynamic number assigned to
|
|
the \fIcipher\fR. This is only useful with fetched \fB\s-1EVP_CIPHER\s0\fRs.
|
|
.PP
|
|
\&\fIEVP_CIPHER_name()\fR and \fIEVP_CIPHER_CTX_name()\fR return the name of the passed
|
|
cipher or context. For fetched ciphers with multiple names, only one
|
|
of them is returned; it's recommended to use \fIEVP_CIPHER_names_do_all()\fR
|
|
instead.
|
|
.PP
|
|
\&\fIEVP_CIPHER_names_do_all()\fR traverses all names for the \fIcipher\fR, and
|
|
calls \fIfn\fR with each name and \fIdata\fR. This is only useful with
|
|
fetched \fB\s-1EVP_CIPHER\s0\fRs.
|
|
.PP
|
|
\&\fIEVP_CIPHER_provider()\fR returns an \fB\s-1OSSL_PROVIDER\s0\fR pointer to the provider
|
|
that implements the given \fB\s-1EVP_CIPHER\s0\fR.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_cipher()\fR returns the \fB\s-1EVP_CIPHER\s0\fR structure when passed
|
|
an \fB\s-1EVP_CIPHER_CTX\s0\fR structure.
|
|
.PP
|
|
\&\fIEVP_CIPHER_mode()\fR and \fIEVP_CIPHER_CTX_mode()\fR return the block cipher mode:
|
|
\&\s-1EVP_CIPH_ECB_MODE\s0, \s-1EVP_CIPH_CBC_MODE\s0, \s-1EVP_CIPH_CFB_MODE\s0, \s-1EVP_CIPH_OFB_MODE\s0,
|
|
\&\s-1EVP_CIPH_CTR_MODE\s0, \s-1EVP_CIPH_GCM_MODE\s0, \s-1EVP_CIPH_CCM_MODE\s0, \s-1EVP_CIPH_XTS_MODE\s0,
|
|
\&\s-1EVP_CIPH_WRAP_MODE\s0, \s-1EVP_CIPH_OCB_MODE\s0 or \s-1EVP_CIPH_SIV_MODE\s0. If the cipher is a
|
|
stream cipher then \s-1EVP_CIPH_STREAM_CIPHER\s0 is returned.
|
|
.PP
|
|
\&\fIEVP_CIPHER_flags()\fR returns any flags associated with the cipher. See
|
|
\&\fIEVP_CIPHER_meth_set_flags()\fR for a list of currently defined flags.
|
|
.PP
|
|
\&\fIEVP_CIPHER_param_to_asn1()\fR sets the AlgorithmIdentifier \*(L"parameter\*(R" based
|
|
on the passed cipher. This will typically include any parameters and an
|
|
\&\s-1IV\s0. The cipher \s-1IV\s0 (if any) must be set when this call is made. This call
|
|
should be made before the cipher is actually \*(L"used\*(R" (before any
|
|
\&\fIEVP_EncryptUpdate()\fR, \fIEVP_DecryptUpdate()\fR calls for example). This function
|
|
may fail if the cipher does not have any \s-1ASN1\s0 support.
|
|
.PP
|
|
\&\fIEVP_CIPHER_asn1_to_param()\fR sets the cipher parameters based on an \s-1ASN1\s0
|
|
AlgorithmIdentifier \*(L"parameter\*(R". The precise effect depends on the cipher
|
|
In the case of \s-1RC2\s0, for example, it will set the \s-1IV\s0 and effective key length.
|
|
This function should be called after the base cipher type is set but before
|
|
the key is set. For example \fIEVP_CipherInit()\fR will be called with the \s-1IV\s0 and
|
|
key set to \s-1NULL\s0, \fIEVP_CIPHER_asn1_to_param()\fR will be called and finally
|
|
\&\fIEVP_CipherInit()\fR again with all parameters except the key set to \s-1NULL\s0. It is
|
|
possible for this function to fail if the cipher does not have any \s-1ASN1\s0 support
|
|
or the parameters cannot be set (for example the \s-1RC2\s0 effective key length
|
|
is not supported.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_ctrl()\fR allows various cipher specific parameters to be determined
|
|
and set.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_rand_key()\fR generates a random key of the appropriate length
|
|
based on the cipher context. The \s-1EVP_CIPHER\s0 can provide its own random key
|
|
generation routine to support keys of a specific form. \fBKey\fR must point to a
|
|
buffer at least as big as the value returned by \fIEVP_CIPHER_CTX_key_length()\fR.
|
|
.PP
|
|
\&\fIEVP_CIPHER_do_all_provided()\fR traverses all ciphers implemented by all activated
|
|
providers in the given library context \fIlibctx\fR, and for each of the
|
|
implementations, calls the given function \fIfn\fR with the implementation method
|
|
and the given \fIarg\fR as argument.
|
|
.SH "RETURN VALUES"
|
|
.IX Header "RETURN VALUES"
|
|
\&\fIEVP_CIPHER_fetch()\fR returns a pointer to a \fB\s-1EVP_CIPHER\s0\fR for success
|
|
and \fB\s-1NULL\s0\fR for failure.
|
|
.PP
|
|
\&\fIEVP_CIPHER_up_ref()\fR returns 1 for success or 0 otherwise.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_new()\fR returns a pointer to a newly created
|
|
\&\fB\s-1EVP_CIPHER_CTX\s0\fR for success and \fB\s-1NULL\s0\fR for failure.
|
|
.PP
|
|
\&\fIEVP_EncryptInit_ex()\fR, \fIEVP_EncryptUpdate()\fR and \fIEVP_EncryptFinal_ex()\fR
|
|
return 1 for success and 0 for failure.
|
|
.PP
|
|
\&\fIEVP_DecryptInit_ex()\fR and \fIEVP_DecryptUpdate()\fR return 1 for success and 0 for failure.
|
|
\&\fIEVP_DecryptFinal_ex()\fR returns 0 if the decrypt failed or 1 for success.
|
|
.PP
|
|
\&\fIEVP_CipherInit_ex()\fR and \fIEVP_CipherUpdate()\fR return 1 for success and 0 for failure.
|
|
\&\fIEVP_CipherFinal_ex()\fR returns 0 for a decryption failure or 1 for success.
|
|
.PP
|
|
\&\fIEVP_Cipher()\fR returns the amount of encrypted / decrypted bytes, or \-1
|
|
on failure, if the flag \fB\s-1EVP_CIPH_FLAG_CUSTOM_CIPHER\s0\fR is set for the
|
|
cipher. \fIEVP_Cipher()\fR returns 1 on success or 0 on failure, if the flag
|
|
\&\fB\s-1EVP_CIPH_FLAG_CUSTOM_CIPHER\s0\fR is not set for the cipher.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_reset()\fR returns 1 for success and 0 for failure.
|
|
.PP
|
|
\&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
|
|
return an \fB\s-1EVP_CIPHER\s0\fR structure or \s-1NULL\s0 on error.
|
|
.PP
|
|
\&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return a \s-1NID\s0.
|
|
.PP
|
|
\&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
|
|
size.
|
|
.PP
|
|
\&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
|
|
length.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_set_padding()\fR always returns 1.
|
|
.PP
|
|
\&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
|
|
length or zero if the cipher does not use an \s-1IV\s0.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_tag_length()\fR return the tag length or zero if the cipher does not
|
|
use a tag.
|
|
.PP
|
|
\&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the \s-1NID\s0 of the cipher's
|
|
\&\s-1OBJECT\s0 \s-1IDENTIFIER\s0 or NID_undef if it has no defined \s-1OBJECT\s0 \s-1IDENTIFIER\s0.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_cipher()\fR returns an \fB\s-1EVP_CIPHER\s0\fR structure.
|
|
.PP
|
|
\&\fIEVP_CIPHER_param_to_asn1()\fR and \fIEVP_CIPHER_asn1_to_param()\fR return greater
|
|
than zero for success and zero or a negative number on failure.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_rand_key()\fR returns 1 for success.
|
|
.SH "CIPHER LISTING"
|
|
.IX Header "CIPHER LISTING"
|
|
All algorithms have a fixed key length unless otherwise stated.
|
|
.PP
|
|
Refer to \*(L"\s-1SEE\s0 \s-1ALSO\s0\*(R" for the full list of ciphers available through the \s-1EVP\s0
|
|
interface.
|
|
.IP "\fIEVP_enc_null()\fR" 4
|
|
.IX Item "EVP_enc_null()"
|
|
Null cipher: does nothing.
|
|
.SH "AEAD INTERFACE"
|
|
.IX Header "AEAD INTERFACE"
|
|
The \s-1EVP\s0 interface for Authenticated Encryption with Associated Data (\s-1AEAD\s0)
|
|
modes are subtly altered and several additional \fIctrl\fR operations are supported
|
|
depending on the mode specified.
|
|
.PP
|
|
To specify additional authenticated data (\s-1AAD\s0), a call to \fIEVP_CipherUpdate()\fR,
|
|
\&\fIEVP_EncryptUpdate()\fR or \fIEVP_DecryptUpdate()\fR should be made with the output
|
|
parameter \fBout\fR set to \fB\s-1NULL\s0\fR.
|
|
.PP
|
|
When decrypting, the return value of \fIEVP_DecryptFinal()\fR or \fIEVP_CipherFinal()\fR
|
|
indicates whether the operation was successful. If it does not indicate success,
|
|
the authentication operation has failed and any output data \fB\s-1MUST\s0 \s-1NOT\s0\fR be used
|
|
as it is corrupted.
|
|
.SS "\s-1GCM\s0 and \s-1OCB\s0 Modes"
|
|
.IX Subsection "GCM and OCB Modes"
|
|
The following \fIctrl\fRs are supported in \s-1GCM\s0 and \s-1OCB\s0 modes.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_SET_IVLEN\s0, ivlen, \s-1NULL\s0)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)"
|
|
Sets the \s-1IV\s0 length. This call can only be made before specifying an \s-1IV\s0. If
|
|
not called a default \s-1IV\s0 length is used.
|
|
.Sp
|
|
For \s-1GCM\s0 \s-1AES\s0 and \s-1OCB\s0 \s-1AES\s0 the default is 12 (i.e. 96 bits). For \s-1OCB\s0 mode the
|
|
maximum is 15.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_GET_TAG\s0, taglen, tag)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)"
|
|
Writes \f(CW\*(C`taglen\*(C'\fR bytes of the tag value to the buffer indicated by \f(CW\*(C`tag\*(C'\fR.
|
|
This call can only be made when encrypting data and \fBafter\fR all data has been
|
|
processed (e.g. after an \fIEVP_EncryptFinal()\fR call).
|
|
.Sp
|
|
For \s-1OCB\s0, \f(CW\*(C`taglen\*(C'\fR must either be 16 or the value previously set via
|
|
\&\fB\s-1EVP_CTRL_AEAD_SET_TAG\s0\fR.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_SET_TAG\s0, taglen, tag)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)"
|
|
Sets the expected tag to \f(CW\*(C`taglen\*(C'\fR bytes from \f(CW\*(C`tag\*(C'\fR.
|
|
The tag length can only be set before specifying an \s-1IV\s0.
|
|
\&\f(CW\*(C`taglen\*(C'\fR must be between 1 and 16 inclusive.
|
|
.Sp
|
|
For \s-1GCM\s0, this call is only valid when decrypting data.
|
|
.Sp
|
|
For \s-1OCB\s0, this call is valid when decrypting data to set the expected tag,
|
|
and before encryption to set the desired tag length.
|
|
.Sp
|
|
In \s-1OCB\s0 mode, calling this before encryption with \f(CW\*(C`tag\*(C'\fR set to \f(CW\*(C`NULL\*(C'\fR sets the
|
|
tag length. If this is not called prior to encryption, a default tag length is
|
|
used.
|
|
.Sp
|
|
For \s-1OCB\s0 \s-1AES\s0, the default tag length is 16 (i.e. 128 bits). It is also the
|
|
maximum tag length for \s-1OCB\s0.
|
|
.SS "\s-1CCM\s0 Mode"
|
|
.IX Subsection "CCM Mode"
|
|
The \s-1EVP\s0 interface for \s-1CCM\s0 mode is similar to that of the \s-1GCM\s0 mode but with a
|
|
few additional requirements and different \fIctrl\fR values.
|
|
.PP
|
|
For \s-1CCM\s0 mode, the total plaintext or ciphertext length \fB\s-1MUST\s0\fR be passed to
|
|
\&\fIEVP_CipherUpdate()\fR, \fIEVP_EncryptUpdate()\fR or \fIEVP_DecryptUpdate()\fR with the output
|
|
and input parameters (\fBin\fR and \fBout\fR) set to \fB\s-1NULL\s0\fR and the length passed in
|
|
the \fBinl\fR parameter.
|
|
.PP
|
|
The following \fIctrl\fRs are supported in \s-1CCM\s0 mode.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_SET_TAG\s0, taglen, tag)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)"
|
|
This call is made to set the expected \fB\s-1CCM\s0\fR tag value when decrypting or
|
|
the length of the tag (with the \f(CW\*(C`tag\*(C'\fR parameter set to \s-1NULL\s0) when encrypting.
|
|
The tag length is often referred to as \fBM\fR. If not set a default value is
|
|
used (12 for \s-1AES\s0). When decrypting, the tag needs to be set before passing
|
|
in data to be decrypted, but as in \s-1GCM\s0 and \s-1OCB\s0 mode, it can be set after
|
|
passing additional authenticated data (see \*(L"\s-1AEAD\s0 \s-1INTERFACE\s0\*(R").
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_CCM_SET_L\s0, ivlen, \s-1NULL\s0)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)"
|
|
Sets the \s-1CCM\s0 \fBL\fR value. If not set a default is used (8 for \s-1AES\s0).
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_SET_IVLEN\s0, ivlen, \s-1NULL\s0)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)"
|
|
Sets the \s-1CCM\s0 nonce (\s-1IV\s0) length. This call can only be made before specifying an
|
|
nonce value. The nonce length is given by \fB15 \- L\fR so it is 7 by default for
|
|
\&\s-1AES\s0.
|
|
.SS "\s-1SIV\s0 Mode"
|
|
.IX Subsection "SIV Mode"
|
|
For \s-1SIV\s0 mode ciphers the behaviour of the \s-1EVP\s0 interface is subtly
|
|
altered and several additional ctrl operations are supported.
|
|
.PP
|
|
To specify any additional authenticated data (\s-1AAD\s0) and/or a Nonce, a call to
|
|
\&\fIEVP_CipherUpdate()\fR, \fIEVP_EncryptUpdate()\fR or \fIEVP_DecryptUpdate()\fR should be made
|
|
with the output parameter \fBout\fR set to \fB\s-1NULL\s0\fR.
|
|
.PP
|
|
\&\s-1RFC5297\s0 states that the Nonce is the last piece of \s-1AAD\s0 before the actual
|
|
encrypt/decrypt takes place. The \s-1API\s0 does not differentiate the Nonce from
|
|
other \s-1AAD\s0.
|
|
.PP
|
|
When decrypting the return value of \fIEVP_DecryptFinal()\fR or \fIEVP_CipherFinal()\fR
|
|
indicates if the operation was successful. If it does not indicate success
|
|
the authentication operation has failed and any output data \fB\s-1MUST\s0 \s-1NOT\s0\fR
|
|
be used as it is corrupted.
|
|
.PP
|
|
The following ctrls are supported in both \s-1SIV\s0 modes.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_GET_TAG\s0, taglen, tag);" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);"
|
|
Writes \fBtaglen\fR bytes of the tag value to the buffer indicated by \fBtag\fR.
|
|
This call can only be made when encrypting data and \fBafter\fR all data has been
|
|
processed (e.g. after an \fIEVP_EncryptFinal()\fR call). For \s-1SIV\s0 mode the taglen must
|
|
be 16.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_SET_TAG\s0, taglen, tag);" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);"
|
|
Sets the expected tag to \fBtaglen\fR bytes from \fBtag\fR. This call is only legal
|
|
when decrypting data and must be made \fBbefore\fR any data is processed (e.g.
|
|
before any \fIEVP_DecryptUpdate()\fR call). For \s-1SIV\s0 mode the taglen must be 16.
|
|
.PP
|
|
\&\s-1SIV\s0 mode makes two passes over the input data, thus, only one call to
|
|
\&\fIEVP_CipherUpdate()\fR, \fIEVP_EncryptUpdate()\fR or \fIEVP_DecryptUpdate()\fR should be made
|
|
with \fBout\fR set to a non\-\fB\s-1NULL\s0\fR value. A call to \fIEVP_Decrypt_Final()\fR or
|
|
\&\fIEVP_CipherFinal()\fR is not required, but will indicate if the update
|
|
operation succeeded.
|
|
.SS "ChaCha20\-Poly1305"
|
|
.IX Subsection "ChaCha20-Poly1305"
|
|
The following \fIctrl\fRs are supported for the ChaCha20\-Poly1305 \s-1AEAD\s0 algorithm.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_SET_IVLEN\s0, ivlen, \s-1NULL\s0)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)"
|
|
Sets the nonce length. This call can only be made before specifying the nonce.
|
|
If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
|
|
nonce length is 12 bytes (i.e. 96\-bits). If a nonce of less than 12 bytes is set
|
|
then the nonce is automatically padded with leading 0 bytes to make it 12 bytes
|
|
in length.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_GET_TAG\s0, taglen, tag)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)"
|
|
Writes \f(CW\*(C`taglen\*(C'\fR bytes of the tag value to the buffer indicated by \f(CW\*(C`tag\*(C'\fR.
|
|
This call can only be made when encrypting data and \fBafter\fR all data has been
|
|
processed (e.g. after an \fIEVP_EncryptFinal()\fR call).
|
|
.Sp
|
|
\&\f(CW\*(C`taglen\*(C'\fR specified here must be 16 (\fB\s-1POLY1305_BLOCK_SIZE\s0\fR, i.e. 128\-bits) or
|
|
less.
|
|
.IP "EVP_CIPHER_CTX_ctrl(ctx, \s-1EVP_CTRL_AEAD_SET_TAG\s0, taglen, tag)" 4
|
|
.IX Item "EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)"
|
|
Sets the expected tag to \f(CW\*(C`taglen\*(C'\fR bytes from \f(CW\*(C`tag\*(C'\fR.
|
|
The tag length can only be set before specifying an \s-1IV\s0.
|
|
\&\f(CW\*(C`taglen\*(C'\fR must be between 1 and 16 (\fB\s-1POLY1305_BLOCK_SIZE\s0\fR) inclusive.
|
|
This call is only valid when decrypting data.
|
|
.SH "NOTES"
|
|
.IX Header "NOTES"
|
|
Where possible the \fB\s-1EVP\s0\fR interface to symmetric ciphers should be used in
|
|
preference to the low level interfaces. This is because the code then becomes
|
|
transparent to the cipher used and much more flexible. Additionally, the
|
|
\&\fB\s-1EVP\s0\fR interface will ensure the use of platform specific cryptographic
|
|
acceleration such as AES-NI (the low level interfaces do not provide the
|
|
guarantee).
|
|
.PP
|
|
\&\s-1PKCS\s0 padding works by adding \fBn\fR padding bytes of value \fBn\fR to make the total
|
|
length of the encrypted data a multiple of the block size. Padding is always
|
|
added so if the data is already a multiple of the block size \fBn\fR will equal
|
|
the block size. For example if the block size is 8 and 11 bytes are to be
|
|
encrypted then 5 padding bytes of value 5 will be added.
|
|
.PP
|
|
When decrypting the final block is checked to see if it has the correct form.
|
|
.PP
|
|
Although the decryption operation can produce an error if padding is enabled,
|
|
it is not a strong test that the input data or key is correct. A random block
|
|
has better than 1 in 256 chance of being of the correct format and problems with
|
|
the input data earlier on will not produce a final decrypt error.
|
|
.PP
|
|
If padding is disabled then the decryption operation will always succeed if
|
|
the total amount of data decrypted is a multiple of the block size.
|
|
.PP
|
|
The functions \fIEVP_EncryptInit()\fR, \fIEVP_EncryptFinal()\fR, \fIEVP_DecryptInit()\fR,
|
|
\&\fIEVP_CipherInit()\fR and \fIEVP_CipherFinal()\fR are obsolete but are retained for
|
|
compatibility with existing code. New code should use \fIEVP_EncryptInit_ex()\fR,
|
|
\&\fIEVP_EncryptFinal_ex()\fR, \fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptFinal_ex()\fR,
|
|
\&\fIEVP_CipherInit_ex()\fR and \fIEVP_CipherFinal_ex()\fR because they can reuse an
|
|
existing context without allocating and freeing it up on each call.
|
|
.PP
|
|
There are some differences between functions \fIEVP_CipherInit()\fR and
|
|
\&\fIEVP_CipherInit_ex()\fR, significant in some circumstances. \fIEVP_CipherInit()\fR fills
|
|
the passed context object with zeros. As a consequence, \fIEVP_CipherInit()\fR does
|
|
not allow step-by-step initialization of the ctx when the \fIkey\fR and \fIiv\fR are
|
|
passed in separate calls. It also means that the flags set for the \s-1CTX\s0 are
|
|
removed, and it is especially important for the
|
|
\&\fB\s-1EVP_CIPHER_CTX_FLAG_WRAP_ALLOW\s0\fR flag treated specially in
|
|
\&\fIEVP_CipherInit_ex()\fR.
|
|
.PP
|
|
\&\fIEVP_get_cipherbynid()\fR, and \fIEVP_get_cipherbyobj()\fR are implemented as macros.
|
|
.SH "BUGS"
|
|
.IX Header "BUGS"
|
|
\&\fB\s-1EVP_MAX_KEY_LENGTH\s0\fR and \fB\s-1EVP_MAX_IV_LENGTH\s0\fR only refer to the internal
|
|
ciphers with default key lengths. If custom ciphers exceed these values the
|
|
results are unpredictable. This is because it has become standard practice to
|
|
define a generic key as a fixed unsigned char array containing
|
|
\&\fB\s-1EVP_MAX_KEY_LENGTH\s0\fR bytes.
|
|
.PP
|
|
The \s-1ASN1\s0 code is incomplete (and sometimes inaccurate) it has only been tested
|
|
for certain common S/MIME ciphers (\s-1RC2\s0, \s-1DES\s0, triple \s-1DES\s0) in \s-1CBC\s0 mode.
|
|
.SH "EXAMPLES"
|
|
.IX Header "EXAMPLES"
|
|
Encrypt a string using \s-1IDEA:\s0
|
|
.PP
|
|
.Vb 10
|
|
\& int do_crypt(char *outfile)
|
|
\& {
|
|
\& unsigned char outbuf[1024];
|
|
\& int outlen, tmplen;
|
|
\& /*
|
|
\& * Bogus key and IV: we\*(Aqd normally set these from
|
|
\& * another source.
|
|
\& */
|
|
\& unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
|
|
\& unsigned char iv[] = {1,2,3,4,5,6,7,8};
|
|
\& char intext[] = "Some Crypto Text";
|
|
\& EVP_CIPHER_CTX *ctx;
|
|
\& FILE *out;
|
|
\&
|
|
\& ctx = EVP_CIPHER_CTX_new();
|
|
\& EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
|
|
\&
|
|
\& if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
|
|
\& /* Error */
|
|
\& EVP_CIPHER_CTX_free(ctx);
|
|
\& return 0;
|
|
\& }
|
|
\& /*
|
|
\& * Buffer passed to EVP_EncryptFinal() must be after data just
|
|
\& * encrypted to avoid overwriting it.
|
|
\& */
|
|
\& if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
|
|
\& /* Error */
|
|
\& EVP_CIPHER_CTX_free(ctx);
|
|
\& return 0;
|
|
\& }
|
|
\& outlen += tmplen;
|
|
\& EVP_CIPHER_CTX_free(ctx);
|
|
\& /*
|
|
\& * Need binary mode for fopen because encrypted data is
|
|
\& * binary data. Also cannot use strlen() on it because
|
|
\& * it won\*(Aqt be NUL terminated and may contain embedded
|
|
\& * NULs.
|
|
\& */
|
|
\& out = fopen(outfile, "wb");
|
|
\& if (out == NULL) {
|
|
\& /* Error */
|
|
\& return 0;
|
|
\& }
|
|
\& fwrite(outbuf, 1, outlen, out);
|
|
\& fclose(out);
|
|
\& return 1;
|
|
\& }
|
|
.Ve
|
|
.PP
|
|
The ciphertext from the above example can be decrypted using the \fBopenssl\fR
|
|
utility with the command line (shown on two lines for clarity):
|
|
.PP
|
|
.Vb 2
|
|
\& openssl idea \-d \e
|
|
\& \-K 000102030405060708090A0B0C0D0E0F \-iv 0102030405060708 <filename
|
|
.Ve
|
|
.PP
|
|
General encryption and decryption function example using \s-1FILE\s0 I/O and \s-1AES128\s0
|
|
with a 128\-bit key:
|
|
.PP
|
|
.Vb 12
|
|
\& int do_crypt(FILE *in, FILE *out, int do_encrypt)
|
|
\& {
|
|
\& /* Allow enough space in output buffer for additional block */
|
|
\& unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
|
|
\& int inlen, outlen;
|
|
\& EVP_CIPHER_CTX *ctx;
|
|
\& /*
|
|
\& * Bogus key and IV: we\*(Aqd normally set these from
|
|
\& * another source.
|
|
\& */
|
|
\& unsigned char key[] = "0123456789abcdeF";
|
|
\& unsigned char iv[] = "1234567887654321";
|
|
\&
|
|
\& /* Don\*(Aqt set key or IV right away; we want to check lengths */
|
|
\& ctx = EVP_CIPHER_CTX_new();
|
|
\& EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
|
|
\& do_encrypt);
|
|
\& OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
|
|
\& OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
|
|
\&
|
|
\& /* Now we can set key and IV */
|
|
\& EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
|
|
\&
|
|
\& for (;;) {
|
|
\& inlen = fread(inbuf, 1, 1024, in);
|
|
\& if (inlen <= 0)
|
|
\& break;
|
|
\& if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
|
|
\& /* Error */
|
|
\& EVP_CIPHER_CTX_free(ctx);
|
|
\& return 0;
|
|
\& }
|
|
\& fwrite(outbuf, 1, outlen, out);
|
|
\& }
|
|
\& if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
|
|
\& /* Error */
|
|
\& EVP_CIPHER_CTX_free(ctx);
|
|
\& return 0;
|
|
\& }
|
|
\& fwrite(outbuf, 1, outlen, out);
|
|
\&
|
|
\& EVP_CIPHER_CTX_free(ctx);
|
|
\& return 1;
|
|
\& }
|
|
.Ve
|
|
.SH "SEE ALSO"
|
|
.IX Header "SEE ALSO"
|
|
\&\fIevp\fR\|(7)
|
|
.PP
|
|
Supported ciphers are listed in:
|
|
.PP
|
|
\&\fIEVP_aes_128_gcm\fR\|(3),
|
|
\&\fIEVP_aria_128_gcm\fR\|(3),
|
|
\&\fIEVP_bf_cbc\fR\|(3),
|
|
\&\fIEVP_camellia_128_ecb\fR\|(3),
|
|
\&\fIEVP_cast5_cbc\fR\|(3),
|
|
\&\fIEVP_chacha20\fR\|(3),
|
|
\&\fIEVP_des_cbc\fR\|(3),
|
|
\&\fIEVP_desx_cbc\fR\|(3),
|
|
\&\fIEVP_idea_cbc\fR\|(3),
|
|
\&\fIEVP_rc2_cbc\fR\|(3),
|
|
\&\fIEVP_rc4\fR\|(3),
|
|
\&\fIEVP_rc5_32_12_16_cbc\fR\|(3),
|
|
\&\fIEVP_seed_cbc\fR\|(3),
|
|
\&\fIEVP_sm4_cbc\fR\|(3)
|
|
.SH "HISTORY"
|
|
.IX Header "HISTORY"
|
|
Support for \s-1OCB\s0 mode was added in OpenSSL 1.1.0.
|
|
.PP
|
|
\&\fB\s-1EVP_CIPHER_CTX\s0\fR was made opaque in OpenSSL 1.1.0. As a result,
|
|
\&\fIEVP_CIPHER_CTX_reset()\fR appeared and \fIEVP_CIPHER_CTX_cleanup()\fR
|
|
disappeared. \fIEVP_CIPHER_CTX_init()\fR remains as an alias for
|
|
\&\fIEVP_CIPHER_CTX_reset()\fR.
|
|
.PP
|
|
The \fIEVP_CIPHER_fetch()\fR, \fIEVP_CIPHER_free()\fR, \fIEVP_CIPHER_up_ref()\fR,
|
|
\&\fIEVP_CIPHER_CTX_set_params()\fR and \fIEVP_CIPHER_CTX_get_params()\fR functions
|
|
were added in 3.0.
|
|
.SH "COPYRIGHT"
|
|
.IX Header "COPYRIGHT"
|
|
Copyright 2000\-2018 The OpenSSL Project Authors. All Rights Reserved.
|
|
.PP
|
|
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use
|
|
this file except in compliance with the License. You can obtain a copy
|
|
in the file \s-1LICENSE\s0 in the source distribution or at
|
|
<https://www.openssl.org/source/license.html>.
|