netinet{,6}: Assert in{,6}_inithead() are only used for system routing tables.
[dragonfly.git] / secure / lib / libcrypto / man / EVP_VerifyInit.3
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133.\" ========================================================================
134.\"
135.IX Title "EVP_VerifyInit 3"
7dc78669 136.TH EVP_VerifyInit 3 "2015-07-09" "1.0.1p" "OpenSSL"
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137.\" For nroff, turn off justification. Always turn off hyphenation; it makes
138.\" way too many mistakes in technical documents.
139.if n .ad l
140.nh
984263bc 141.SH "NAME"
74dab6c2 142EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal \- EVP signature verification functions
984263bc 143.SH "SYNOPSIS"
8b0cefbb 144.IX Header "SYNOPSIS"
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145.Vb 1
146\& #include <openssl/evp.h>
e257b235 147\&
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148\& int EVP_VerifyInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
149\& int EVP_VerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
150\& int EVP_VerifyFinal(EVP_MD_CTX *ctx,unsigned char *sigbuf, unsigned int siglen,EVP_PKEY *pkey);
e257b235 151\&
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152\& int EVP_VerifyInit(EVP_MD_CTX *ctx, const EVP_MD *type);
153.Ve
154.SH "DESCRIPTION"
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155.IX Header "DESCRIPTION"
156The \s-1EVP\s0 signature verification routines are a high level interface to digital
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157signatures.
158.PP
8b0cefbb 159\&\fIEVP_VerifyInit_ex()\fR sets up verification context \fBctx\fR to use digest
5a44c043 160\&\fBtype\fR from \s-1ENGINE \s0\fBimpl\fR. \fBctx\fR must be initialized by calling
8b0cefbb 161\&\fIEVP_MD_CTX_init()\fR before calling this function.
984263bc 162.PP
8b0cefbb 163\&\fIEVP_VerifyUpdate()\fR hashes \fBcnt\fR bytes of data at \fBd\fR into the
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164verification context \fBctx\fR. This function can be called several times on the
165same \fBctx\fR to include additional data.
166.PP
8b0cefbb 167\&\fIEVP_VerifyFinal()\fR verifies the data in \fBctx\fR using the public key \fBpkey\fR
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168and against the \fBsiglen\fR bytes at \fBsigbuf\fR.
169.PP
8b0cefbb 170\&\fIEVP_VerifyInit()\fR initializes verification context \fBctx\fR to use the default
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171implementation of digest \fBtype\fR.
172.SH "RETURN VALUES"
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173.IX Header "RETURN VALUES"
174\&\fIEVP_VerifyInit_ex()\fR and \fIEVP_VerifyUpdate()\fR return 1 for success and 0 for
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175failure.
176.PP
8b0cefbb 177\&\fIEVP_VerifyFinal()\fR returns 1 for a correct signature, 0 for failure and \-1 if some
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178other error occurred.
179.PP
8b0cefbb 180The error codes can be obtained by \fIERR_get_error\fR\|(3).
984263bc 181.SH "NOTES"
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182.IX Header "NOTES"
183The \fB\s-1EVP\s0\fR interface to digital signatures should almost always be used in
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184preference to the low level interfaces. This is because the code then becomes
185transparent to the algorithm used and much more flexible.
186.PP
187Due to the link between message digests and public key algorithms the correct
188digest algorithm must be used with the correct public key type. A list of
189algorithms and associated public key algorithms appears in
8b0cefbb 190\&\fIEVP_DigestInit\fR\|(3).
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191.PP
192The call to \fIEVP_VerifyFinal()\fR internally finalizes a copy of the digest context.
193This means that calls to \fIEVP_VerifyUpdate()\fR and \fIEVP_VerifyFinal()\fR can be called
194later to digest and verify additional data.
195.PP
196Since only a copy of the digest context is ever finalized the context must
197be cleaned up after use by calling \fIEVP_MD_CTX_cleanup()\fR or a memory leak
198will occur.
199.SH "BUGS"
8b0cefbb 200.IX Header "BUGS"
984263bc 201Older versions of this documentation wrongly stated that calls to
8b0cefbb 202\&\fIEVP_VerifyUpdate()\fR could not be made after calling \fIEVP_VerifyFinal()\fR.
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203.PP
204Since the public key is passed in the call to \fIEVP_SignFinal()\fR any error
205relating to the private key (for example an unsuitable key and digest
206combination) will not be indicated until after potentially large amounts of
207data have been passed through \fIEVP_SignUpdate()\fR.
208.PP
209It is not possible to change the signing parameters using these function.
210.PP
211The previous two bugs are fixed in the newer EVP_VerifyDigest*() function.
984263bc 212.SH "SEE ALSO"
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213.IX Header "SEE ALSO"
214\&\fIevp\fR\|(3),
215\&\fIEVP_SignInit\fR\|(3),
216\&\fIEVP_DigestInit\fR\|(3), \fIerr\fR\|(3),
217\&\fIevp\fR\|(3), \fIhmac\fR\|(3), \fImd2\fR\|(3),
218\&\fImd5\fR\|(3), \fImdc2\fR\|(3), \fIripemd\fR\|(3),
219\&\fIsha\fR\|(3), \fIdgst\fR\|(1)
984263bc 220.SH "HISTORY"
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221.IX Header "HISTORY"
222\&\fIEVP_VerifyInit()\fR, \fIEVP_VerifyUpdate()\fR and \fIEVP_VerifyFinal()\fR are
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223available in all versions of SSLeay and OpenSSL.
224.PP
8b0cefbb 225\&\fIEVP_VerifyInit_ex()\fR was added in OpenSSL 0.9.7