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Diffstat (limited to 'secure/lib/libcrypto/man/BIO_f_md.3')
| -rw-r--r-- | secure/lib/libcrypto/man/BIO_f_md.3 | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/secure/lib/libcrypto/man/BIO_f_md.3 b/secure/lib/libcrypto/man/BIO_f_md.3 new file mode 100644 index 0000000..39688fb --- /dev/null +++ b/secure/lib/libcrypto/man/BIO_f_md.3 @@ -0,0 +1,282 @@ +.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.28) +.\" +.\" Standard preamble: +.\" ======================================================================== +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.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. \*(C+ will +.\" give a nicer C++. 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Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.if n .ad l +.nh +.SH "NAME" +BIO_f_md, BIO_set_md, BIO_get_md, BIO_get_md_ctx \- message digest BIO filter +.SH "SYNOPSIS" +.IX Header "SYNOPSIS" +.Vb 2 +\& #include <openssl/bio.h> +\& #include <openssl/evp.h> +\& +\& BIO_METHOD * BIO_f_md(void); +\& int BIO_set_md(BIO *b,EVP_MD *md); +\& int BIO_get_md(BIO *b,EVP_MD **mdp); +\& int BIO_get_md_ctx(BIO *b,EVP_MD_CTX **mdcp); +.Ve +.SH "DESCRIPTION" +.IX Header "DESCRIPTION" +\&\fIBIO_f_md()\fR returns the message digest \s-1BIO\s0 method. This is a filter +\&\s-1BIO\s0 that digests any data passed through it, it is a \s-1BIO\s0 wrapper +for the digest routines \fIEVP_DigestInit()\fR, \fIEVP_DigestUpdate()\fR +and \fIEVP_DigestFinal()\fR. +.PP +Any data written or read through a digest \s-1BIO\s0 using \fIBIO_read()\fR and +\&\fIBIO_write()\fR is digested. +.PP +\&\fIBIO_gets()\fR, if its \fBsize\fR parameter is large enough finishes the +digest calculation and returns the digest value. \fIBIO_puts()\fR is +not supported. +.PP +\&\fIBIO_reset()\fR reinitialises a digest \s-1BIO.\s0 +.PP +\&\fIBIO_set_md()\fR sets the message digest of \s-1BIO \s0\fBb\fR to \fBmd\fR: this +must be called to initialize a digest \s-1BIO\s0 before any data is +passed through it. It is a \fIBIO_ctrl()\fR macro. +.PP +\&\fIBIO_get_md()\fR places the a pointer to the digest BIOs digest method +in \fBmdp\fR, it is a \fIBIO_ctrl()\fR macro. +.PP +\&\fIBIO_get_md_ctx()\fR returns the digest BIOs context into \fBmdcp\fR. +.SH "NOTES" +.IX Header "NOTES" +The context returned by \fIBIO_get_md_ctx()\fR can be used in calls +to \fIEVP_DigestFinal()\fR and also the signature routines \fIEVP_SignFinal()\fR +and \fIEVP_VerifyFinal()\fR. +.PP +The context returned by \fIBIO_get_md_ctx()\fR is an internal context +structure. Changes made to this context will affect the digest +\&\s-1BIO\s0 itself and the context pointer will become invalid when the digest +\&\s-1BIO\s0 is freed. +.PP +After the digest has been retrieved from a digest \s-1BIO\s0 it must be +reinitialized by calling \fIBIO_reset()\fR, or \fIBIO_set_md()\fR before any more +data is passed through it. +.PP +If an application needs to call \fIBIO_gets()\fR or \fIBIO_puts()\fR through +a chain containing digest BIOs then this can be done by prepending +a buffering \s-1BIO.\s0 +.PP +Before OpenSSL 1.0.0 the call to \fIBIO_get_md_ctx()\fR would only work if the \s-1BIO\s0 +had been initialized for example by calling \fIBIO_set_md()\fR ). In OpenSSL +1.0.0 and later the context is always returned and the \s-1BIO\s0 is state is set +to initialized. This allows applications to initialize the context externally +if the standard calls such as \fIBIO_set_md()\fR are not sufficiently flexible. +.SH "RETURN VALUES" +.IX Header "RETURN VALUES" +\&\fIBIO_f_md()\fR returns the digest \s-1BIO\s0 method. +.PP +\&\fIBIO_set_md()\fR, \fIBIO_get_md()\fR and \fIBIO_md_ctx()\fR return 1 for success and +0 for failure. +.SH "EXAMPLES" +.IX Header "EXAMPLES" +The following example creates a \s-1BIO\s0 chain containing an \s-1SHA1\s0 and \s-1MD5\s0 +digest \s-1BIO\s0 and passes the string \*(L"Hello World\*(R" through it. Error +checking has been omitted for clarity. +.PP +.Vb 10 +\& BIO *bio, *mdtmp; +\& char message[] = "Hello World"; +\& bio = BIO_new(BIO_s_null()); +\& mdtmp = BIO_new(BIO_f_md()); +\& BIO_set_md(mdtmp, EVP_sha1()); +\& /* For BIO_push() we want to append the sink BIO and keep a note of +\& * the start of the chain. +\& */ +\& bio = BIO_push(mdtmp, bio); +\& mdtmp = BIO_new(BIO_f_md()); +\& BIO_set_md(mdtmp, EVP_md5()); +\& bio = BIO_push(mdtmp, bio); +\& /* Note: mdtmp can now be discarded */ +\& BIO_write(bio, message, strlen(message)); +.Ve +.PP +The next example digests data by reading through a chain instead: +.PP +.Vb 10 +\& BIO *bio, *mdtmp; +\& char buf[1024]; +\& int rdlen; +\& bio = BIO_new_file(file, "rb"); +\& mdtmp = BIO_new(BIO_f_md()); +\& BIO_set_md(mdtmp, EVP_sha1()); +\& bio = BIO_push(mdtmp, bio); +\& mdtmp = BIO_new(BIO_f_md()); +\& BIO_set_md(mdtmp, EVP_md5()); +\& bio = BIO_push(mdtmp, bio); +\& do { +\& rdlen = BIO_read(bio, buf, sizeof(buf)); +\& /* Might want to do something with the data here */ +\& } while(rdlen > 0); +.Ve +.PP +This next example retrieves the message digests from a \s-1BIO\s0 chain and +outputs them. This could be used with the examples above. +.PP +.Vb 10 +\& BIO *mdtmp; +\& unsigned char mdbuf[EVP_MAX_MD_SIZE]; +\& int mdlen; +\& int i; +\& mdtmp = bio; /* Assume bio has previously been set up */ +\& do { +\& EVP_MD *md; +\& mdtmp = BIO_find_type(mdtmp, BIO_TYPE_MD); +\& if(!mdtmp) break; +\& BIO_get_md(mdtmp, &md); +\& printf("%s digest", OBJ_nid2sn(EVP_MD_type(md))); +\& mdlen = BIO_gets(mdtmp, mdbuf, EVP_MAX_MD_SIZE); +\& for(i = 0; i < mdlen; i++) printf(":%02X", mdbuf[i]); +\& printf("\en"); +\& mdtmp = BIO_next(mdtmp); +\& } while(mdtmp); +\& +\& BIO_free_all(bio); +.Ve +.SH "BUGS" +.IX Header "BUGS" +The lack of support for \fIBIO_puts()\fR and the non standard behaviour of +\&\fIBIO_gets()\fR could be regarded as anomalous. It could be argued that \fIBIO_gets()\fR +and \fIBIO_puts()\fR should be passed to the next \s-1BIO\s0 in the chain and digest +the data passed through and that digests should be retrieved using a +separate \fIBIO_ctrl()\fR call. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +\&\s-1TBA\s0 |
