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New docs for EVP_Digest{Sign,Verify}*() function. Update existing docs.

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This commit is contained in:
Dr. Stephen Henson 2006-07-12 12:31:30 +00:00
parent e454929558
commit 29cf84c692
8 changed files with 203 additions and 17 deletions
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10
crypto/evp/bio_md.c
View File

@ -192,13 +192,9 @@ static long md_ctrl(BIO *b, int cmd, long num, void *ptr)
ret=0;
break;
case BIO_C_GET_MD_CTX:
if (b->init)
{
pctx=ptr;
*pctx=ctx;
}
else
ret=0;
pctx=ptr;
*pctx=ctx;
b->init = 1;
break;
case BIO_C_DO_STATE_MACHINE:
BIO_clear_retry_flags(b);

7
crypto/evp/evp.h
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@ -453,11 +453,8 @@ typedef int (EVP_PBE_KEYGEN)(EVP_CIPHER_CTX *ctx, const char *pass, int passlen,
#define EVP_VerifyUpdate(a,b,c) EVP_DigestUpdate(a,b,c)
#define EVP_OpenUpdate(a,b,c,d,e) EVP_DecryptUpdate(a,b,c,d,e)
#define EVP_SealUpdate(a,b,c,d,e) EVP_EncryptUpdate(a,b,c,d,e)
#define EVP_SignDigestUpdate(a,b,c) EVP_DigestUpdate(a,b,c)
#define EVP_VerifyDigestUpdate(a,b,c) EVP_DigestUpdate(a,b,c)
#define EVP_DigestSignUpdate(a,b,c) EVP_DigestUpdate(a,b,c)
#define EVP_DigestVerifyUpdate(a,b,c) EVP_DigestUpdate(a,b,c)
#define EVP_DigestSignUpdate(a,b,c) EVP_DigestUpdate(a,b,c)
#define EVP_DigestVerifyUpdate(a,b,c) EVP_DigestUpdate(a,b,c)
#ifdef CONST_STRICT
void BIO_set_md(BIO *,const EVP_MD *md);

6
doc/crypto/BIO_f_md.pod
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@ -58,6 +58,12 @@ If an application needs to call BIO_gets() or BIO_puts() through
a chain containing digest BIOs then this can be done by prepending
a buffering BIO.
Before OpenSSL 0.9.9 the call to BIO_get_md_ctx() would only work if the BIO
had been initialized for example by calling BIO_set_md() ). In OpenSSL
0.9.9 and later the context is always returned and the BIO is state is set
to initialized. This allows applications to initialize the context externally
if the standard calls such as BIO_set_md() are not sufficiently flexible.
=head1 RETURN VALUES
BIO_f_md() returns the digest BIO method.

87
doc/crypto/EVP_DigestSignInit.pod Normal file
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@ -0,0 +1,87 @@
=pod
=head1 NAME
EVP_DigestSignInit, EVP_DigestSignUpdate, EVP_DigestSignFinal - EVP signing functions
=head1 SYNOPSIS
#include <openssl/evp.h>
int EVP_DigestSignInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
int EVP_DigestSignFinal(EVP_MD_CTX *ctx, unsigned char *sig, size_t *siglen);
=head1 DESCRIPTION
The EVP signature routines are a high level interface to digital signatures.
EVP_DigestSignInit() sets up signing context B<ctx> to use digest B<type> from
ENGINE B<impl> and private key B<pkey>. B<ctx> must be initialized with
EVP_MD_CTX_init() before calling this function. If B<pctx> is not NULL the
EVP_PKEY_CTX of the signing operation will be written to B<*pctx>: this can
be used to set alternative signing options.
EVP_DigestSignUpdate() hashes B<cnt> bytes of data at B<d> into the
signature context B<ctx>. This function can be called several times on the
same B<ctx> to include additional data. This function is currently implemented
usig a macro.
EVP_DigestSignFinal() signs the data in B<ctx> places the signature in B<sig>.
If B<sig> is B<NULL> then the maximum size of the output buffer is written to
the B<siglen> parameter. If B<sig> is not B<NULL> then before the call the
B<siglen> parameter should contain the length of the B<sig> buffer, if the
call is successful the signature is written to B<sig> and the amount of data
written to B<siglen>.
=head1 RETURN VALUES
EVP_DigestSignInit() EVP_DigestSignUpdate() and EVP_DigestSignaFinal() return
1 for success and 0 or a negative value for failure. In particular a return
value of -2 indicates the operation is not supported by the public key
algorithm.
The error codes can be obtained from L<ERR_get_error(3)|ERR_get_error(3)>.
=head1 NOTES
The B<EVP> interface to digital signatures should almost always be used in
preference to the low level interfaces. This is because the code then becomes
transparent to the algorithm used and much more flexible.
In previous versions of OpenSSL there was a link between message digest types
and public key algorithms. This meant that "clone" digests such as EVP_dss1()
needed to be used to sign using SHA1 and DSA. This is no longer necessary and
the use of clone digest is now discouraged.
For some key types and parameters the random number generator must be seeded
or the operation will fail.
The call to EVP_DigestSignFinal() internally finalizes a copy of the digest
context. This means that calls to EVP_DigestSignUpdate() and
EVP_DigestSignFinal() can be called later to digest and sign additional data.
Since only a copy of the digest context is ever finalized the context must
be cleaned up after use by calling EVP_MD_CTX_cleanup() or a memory leak
will occur.
The use of EVP_PKEY_size() with these functions is discouraged because some
signature operations may have a signature length which depends on the
parameters set. As a result EVP_PKEY_size() would have to return a value
which indicates the maximum possible signature for any set of parameters.
=head1 SEE ALSO
L<EVP_DigestVerifyInit(3)|EVP_DigestVerifyInit(3)>,
L<EVP_DigestInit(3)|EVP_DigestInit(3)>, L<err(3)|err(3)>,
L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,
L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)>
=head1 HISTORY
EVP_DigestSignInit(), EVP_DigestSignUpdate() and EVP_DigestSignFinal()
were first added to OpenSSL 0.9.9.
=cut

82
doc/crypto/EVP_DigestVerifyInit.pod Normal file
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@ -0,0 +1,82 @@
=pod
=head1 NAME
EVP_DigestVerifyInit, EVP_DigestVerifyUpdate, EVP_DigestVerifyFinal - EVP signature verification functions
=head1 SYNOPSIS
#include <openssl/evp.h>
int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, unsigned char *sig, size_t siglen);
=head1 DESCRIPTION
The EVP signature routines are a high level interface to digital signatures.
EVP_DigestVerifyInit() sets up verification context B<ctx> to use digest
B<type> from ENGINE B<impl> and public key B<pkey>. B<ctx> must be initialized
with EVP_MD_CTX_init() before calling this function. If B<pctx> is not NULL the
EVP_PKEY_CTX of the verification operation will be written to B<*pctx>: this
can be used to set alternative verification options.
EVP_DigestVerifyUpdate() hashes B<cnt> bytes of data at B<d> into the
verification context B<ctx>. This function can be called several times on the
same B<ctx> to include additional data. This function is currently implemented
using a macro.
EVP_DigestVerifyFinal() verifies the data in B<ctx> against the signature in
B<sig> of length B<siglen>.
=head1 RETURN VALUES
EVP_DigestVerifyInit() and EVP_DigestVerifyUpdate() return 1 for success and 0
or a negative value for failure. In particular a return value of -2 indicates
the operation is not supported by the public key algorithm.
Unlike other functions the return value 0 from EVP_DigestVerifyFinal() only
indicates that the signature did not not verify successfully (that is tbs did
not match the original data or the signature was of invalid form) it is not an
indication of a more serious error.
The error codes can be obtained from L<ERR_get_error(3)|ERR_get_error(3)>.
=head1 NOTES
The B<EVP> interface to digital signatures should almost always be used in
preference to the low level interfaces. This is because the code then becomes
transparent to the algorithm used and much more flexible.
In previous versions of OpenSSL there was a link between message digest types
and public key algorithms. This meant that "clone" digests such as EVP_dss1()
needed to be used to sign using SHA1 and DSA. This is no longer necessary and
the use of clone digest is now discouraged.
For some key types and parameters the random number generator must be seeded
or the operation will fail.
The call to EVP_DigestVerifyFinal() internally finalizes a copy of the digest
context. This means that calls to EVP_VerifyUpdate() and EVP_VerifyFinal() can
be called later to digest and verify additional data.
Since only a copy of the digest context is ever finalized the context must
be cleaned up after use by calling EVP_MD_CTX_cleanup() or a memory leak
will occur.
=head1 SEE ALSO
L<EVP_DigestSignInit(3)|EVP_DigestSignInit(3)>,
L<EVP_DigestInit(3)|EVP_DigestInit(3)>, L<err(3)|err(3)>,
L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,
L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)>
=head1 HISTORY
EVP_DigestVerifyInit(), EVP_DigestVerifyUpdate() and EVP_DigestVerifyFinal()
were first added to OpenSSL 0.9.9.
=cut

10
doc/crypto/EVP_PKEY_verify.pod
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@ -34,11 +34,11 @@ context if several operations are performed using the same parameters.
=head1 RETURN VALUES
EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification
was successful and 0 if it failed. Unlike other functions the return value
0 only indicates that the signature did not not verify successfully (that is
tbs did not match the original data or the signature was of invalid form)
it is not an indication of a more serious error.
EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was
successful and 0 if it failed. Unlike other functions the return value 0 from
EVP_PKEY_verify() only indicates that the signature did not not verify
successfully (that is tbs did not match the original data or the signature was
of invalid form) it is not an indication of a more serious error.
A negative value indicates an error other that signature verification failure.
In particular a return value of -2 indicates the operation is not supported by

9
doc/crypto/EVP_SignInit.pod
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@ -77,6 +77,15 @@ will occur.
Older versions of this documentation wrongly stated that calls to
EVP_SignUpdate() could not be made after calling EVP_SignFinal().
Since the private key is passed in the call to EVP_SignFinal() any error
relating to the private key (for example an unsuitable key and digest
combination) will not be indicated until after potentially large amounts of
data have been passed through EVP_SignUpdate().
It is not possible to change the signing parameters using these function.
The previous two bugs are fixed in the newer EVP_SignDigest*() function.
=head1 SEE ALSO
L<EVP_VerifyInit(3)|EVP_VerifyInit(3)>,

9
doc/crypto/EVP_VerifyInit.pod
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@ -67,6 +67,15 @@ will occur.
Older versions of this documentation wrongly stated that calls to
EVP_VerifyUpdate() could not be made after calling EVP_VerifyFinal().
Since the public key is passed in the call to EVP_SignFinal() any error
relating to the private key (for example an unsuitable key and digest
combination) will not be indicated until after potentially large amounts of
data have been passed through EVP_SignUpdate().
It is not possible to change the signing parameters using these function.
The previous two bugs are fixed in the newer EVP_VerifyDigest*() function.
=head1 SEE ALSO
L<evp(3)|evp(3)>,