368 lines
15 KiB
Groff
368 lines
15 KiB
Groff
.\" Automatically generated by Pod::Man version 1.02
|
|
.\" Sun Apr 8 15:40:21 2001
|
|
.\"
|
|
.\" Standard preamble:
|
|
.\" ======================================================================
|
|
.de Sh \" Subsection heading
|
|
.br
|
|
.if t .Sp
|
|
.ne 5
|
|
.PP
|
|
\fB\\$1\fR
|
|
.PP
|
|
..
|
|
.de Sp \" Vertical space (when we can't use .PP)
|
|
.if t .sp .5v
|
|
.if n .sp
|
|
..
|
|
.de Ip \" List item
|
|
.br
|
|
.ie \\n(.$>=3 .ne \\$3
|
|
.el .ne 3
|
|
.IP "\\$1" \\$2
|
|
..
|
|
.de Vb \" Begin verbatim text
|
|
.ft CW
|
|
.nf
|
|
.ne \\$1
|
|
..
|
|
.de Ve \" End verbatim text
|
|
.ft R
|
|
|
|
.fi
|
|
..
|
|
.\" Set up some character translations and predefined strings. \*(-- will
|
|
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
|
|
.\" double quote, and \*(R" will give a right double quote. | will give a
|
|
.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used
|
|
.\" to do unbreakable dashes and therefore won't be available. \*(C` and
|
|
.\" \*(C' expand to `' in nroff, nothing in troff, for use with C<>
|
|
.tr \(*W-|\(bv\*(Tr
|
|
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
|
|
.ie n \{\
|
|
. ds -- \(*W-
|
|
. ds PI pi
|
|
. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
|
|
. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
|
|
. ds L" ""
|
|
. ds R" ""
|
|
. ds C` `
|
|
. ds C' '
|
|
'br\}
|
|
.el\{\
|
|
. ds -- \|\(em\|
|
|
. ds PI \(*p
|
|
. ds L" ``
|
|
. ds R" ''
|
|
'br\}
|
|
.\"
|
|
.\" If the F register is turned on, we'll generate index entries on stderr
|
|
.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and
|
|
.\" index entries marked with X<> in POD. Of course, you'll have to process
|
|
.\" the output yourself in some meaningful fashion.
|
|
.if \nF \{\
|
|
. de IX
|
|
. tm Index:\\$1\t\\n%\t"\\$2"
|
|
. .
|
|
. nr % 0
|
|
. rr F
|
|
.\}
|
|
.\"
|
|
.\" For nroff, turn off justification. Always turn off hyphenation; it
|
|
.\" makes way too many mistakes in technical documents.
|
|
.hy 0
|
|
.if n .na
|
|
.\"
|
|
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
|
|
.\" Fear. Run. Save yourself. No user-serviceable parts.
|
|
.bd B 3
|
|
. \" fudge factors for nroff and troff
|
|
.if n \{\
|
|
. ds #H 0
|
|
. ds #V .8m
|
|
. ds #F .3m
|
|
. ds #[ \f1
|
|
. ds #] \fP
|
|
.\}
|
|
.if t \{\
|
|
. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
|
|
. ds #V .6m
|
|
. ds #F 0
|
|
. ds #[ \&
|
|
. ds #] \&
|
|
.\}
|
|
. \" simple accents for nroff and troff
|
|
.if n \{\
|
|
. ds ' \&
|
|
. ds ` \&
|
|
. ds ^ \&
|
|
. ds , \&
|
|
. ds ~ ~
|
|
. ds /
|
|
.\}
|
|
.if t \{\
|
|
. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
|
|
. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
|
|
. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
|
|
. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
|
|
. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
|
|
. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
|
|
.\}
|
|
. \" troff and (daisy-wheel) nroff accents
|
|
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
|
|
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
|
|
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
|
|
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
|
|
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
|
|
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
|
|
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
|
|
.ds ae a\h'-(\w'a'u*4/10)'e
|
|
.ds Ae A\h'-(\w'A'u*4/10)'E
|
|
. \" corrections for vroff
|
|
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
|
|
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
|
|
. \" for low resolution devices (crt and lpr)
|
|
.if \n(.H>23 .if \n(.V>19 \
|
|
\{\
|
|
. ds : e
|
|
. ds 8 ss
|
|
. ds o a
|
|
. ds d- d\h'-1'\(ga
|
|
. ds D- D\h'-1'\(hy
|
|
. ds th \o'bp'
|
|
. ds Th \o'LP'
|
|
. ds ae ae
|
|
. ds Ae AE
|
|
.\}
|
|
.rm #[ #] #H #V #F C
|
|
.\" ======================================================================
|
|
.\"
|
|
.IX Title "EVP_EncryptInit 3"
|
|
.TH EVP_EncryptInit 3 "0.9.5a" "2000-07-23" "OpenSSL"
|
|
.UC
|
|
.SH "NAME"
|
|
EVP_EncryptInit, EVP_EncryptUpdate, EVP_EncryptFinal \- \s-1EVP\s0 cipher routines
|
|
.SH "LIBRARY"
|
|
libcrypto, -lcrypto
|
|
.SH "SYNOPSIS"
|
|
.IX Header "SYNOPSIS"
|
|
.Vb 1
|
|
\& #include <openssl/evp.h>
|
|
.Ve
|
|
.Vb 6
|
|
\& void EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& unsigned char *key, unsigned char *iv);
|
|
\& void EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& int *outl, unsigned char *in, int inl);
|
|
\& void EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& int *outl);
|
|
.Ve
|
|
.Vb 6
|
|
\& void EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& unsigned char *key, unsigned char *iv);
|
|
\& void EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& int *outl, unsigned char *in, int inl);
|
|
\& int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
|
|
\& int *outl);
|
|
.Ve
|
|
.Vb 6
|
|
\& void EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
\& unsigned char *key, unsigned char *iv, int enc);
|
|
\& void EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
\& int *outl, unsigned char *in, int inl);
|
|
\& int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
|
|
\& int *outl);
|
|
.Ve
|
|
.Vb 1
|
|
\& void EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
|
|
.Ve
|
|
.Vb 3
|
|
\& const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
|
|
\& #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
|
|
\& #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
|
|
.Ve
|
|
.Vb 4
|
|
\& #define EVP_CIPHER_nid(e) ((e)->nid)
|
|
\& #define EVP_CIPHER_block_size(e) ((e)->block_size)
|
|
\& #define EVP_CIPHER_key_length(e) ((e)->key_len)
|
|
\& #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
|
|
.Ve
|
|
.Vb 7
|
|
\& int EVP_CIPHER_type(const EVP_CIPHER *ctx);
|
|
\& #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher)
|
|
\& #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid)
|
|
\& #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size)
|
|
\& #define EVP_CIPHER_CTX_key_length(e) ((e)->cipher->key_len)
|
|
\& #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len)
|
|
\& #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
|
|
.Ve
|
|
.Vb 2
|
|
\& 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);
|
|
.Ve
|
|
.SH "DESCRIPTION"
|
|
.IX Header "DESCRIPTION"
|
|
The \s-1EVP\s0 cipher routines are a high level interface to certain
|
|
symmetric ciphers.
|
|
.PP
|
|
\&\fIEVP_EncryptInit()\fR initialises a cipher context \fBctx\fR for encryption
|
|
with cipher \fBtype\fR. \fBtype\fR is normally supplied by a function such
|
|
as \fIEVP_des_cbc()\fR . \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. This is normally done when the
|
|
\&\fIEVP_CIPHER_asn1_to_param()\fR function is called to set the cipher
|
|
parameters from an \s-1ASN1\s0 AlgorithmIdentifier and the key from a
|
|
different source.
|
|
.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 \fBoutl\fR should contain sufficient
|
|
room. The actual number of bytes written is placed in \fBoutl\fR.
|
|
.PP
|
|
\&\fIEVP_EncryptFinal()\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). 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
|
|
\&\fIEVP_DecryptInit()\fR, \fIEVP_DecryptUpdate()\fR and \fIEVP_DecryptFinal()\fR are the
|
|
corresponding decryption operations. \fIEVP_DecryptFinal()\fR will return an
|
|
error code if the final block is not correctly formatted. The parameters
|
|
and restrictions are identical to the encryption operations except that
|
|
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()\fR, \fIEVP_CipherUpdate()\fR and \fIEVP_CipherFinal()\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 and 0 for decryption.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_cleanup()\fR clears all information from a cipher context.
|
|
It should be called after all operations using a cipher are complete
|
|
so sensitive information does not remain in memory.
|
|
.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_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.
|
|
.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_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_IV_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_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_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
|
|
does not have an \fB\s-1EVP_CIPHER\s0\fR structure).
|
|
.SH "RETURN VALUES"
|
|
.IX Header "RETURN VALUES"
|
|
\&\fIEVP_EncryptInit()\fR, \fIEVP_EncryptUpdate()\fR and \fIEVP_EncryptFinal()\fR do not return
|
|
values.
|
|
.PP
|
|
\&\fIEVP_DecryptInit()\fR and \fIEVP_DecryptUpdate()\fR do not return values.
|
|
\&\fIEVP_DecryptFinal()\fR returns 0 if the decrypt failed or 1 for success.
|
|
.PP
|
|
\&\fIEVP_CipherInit()\fR and \fIEVP_CipherUpdate()\fR do not return values.
|
|
\&\fIEVP_CipherFinal()\fR returns 1 for a decryption failure or 1 for success, if
|
|
the operation is encryption then it always returns 1.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_cleanup()\fR does not return a value.
|
|
.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_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_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 1 for
|
|
success or zero for failure.
|
|
.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.
|
|
.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, 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.
|
|
.SH "BUGS"
|
|
.IX Header "BUGS"
|
|
The current \fB\s-1EVP\s0\fR cipher interface is not as flexible as it should be. Only
|
|
certain \*(L"spot\*(R" encryption algorithms can be used for ciphers which have various
|
|
parameters associated with them (\s-1RC2\s0, \s-1RC5\s0 for example) this is inadequate.
|
|
.PP
|
|
Several of the functions do not return error codes because the software versions
|
|
can never fail. This is not true of hardware versions.
|
|
.SH "SEE ALSO"
|
|
.IX Header "SEE ALSO"
|
|
evp(3)
|
|
.SH "HISTORY"
|
|
.IX Header "HISTORY"
|