Merge branch 'vendor/OPENSSL'
[dragonfly.git] / secure / lib / libcrypto / man / EVP_VerifyInit.3
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132.\" ========================================================================
133.\"
134.IX Title "EVP_VerifyInit 3"
fc468453 135.TH EVP_VerifyInit 3 "2010-02-27" "0.9.8m" "OpenSSL"
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136.\" For nroff, turn off justification. Always turn off hyphenation; it makes
137.\" way too many mistakes in technical documents.
138.if n .ad l
139.nh
984263bc 140.SH "NAME"
74dab6c2 141EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal \- EVP signature verification functions
984263bc 142.SH "SYNOPSIS"
8b0cefbb 143.IX Header "SYNOPSIS"
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144.Vb 1
145\& #include <openssl/evp.h>
e257b235 146\&
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147\& int EVP_VerifyInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
148\& int EVP_VerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
149\& int EVP_VerifyFinal(EVP_MD_CTX *ctx,unsigned char *sigbuf, unsigned int siglen,EVP_PKEY *pkey);
e257b235 150\&
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151\& int EVP_VerifyInit(EVP_MD_CTX *ctx, const EVP_MD *type);
152.Ve
153.SH "DESCRIPTION"
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154.IX Header "DESCRIPTION"
155The \s-1EVP\s0 signature verification routines are a high level interface to digital
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156signatures.
157.PP
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158\&\fIEVP_VerifyInit_ex()\fR sets up verification context \fBctx\fR to use digest
159\&\fBtype\fR from \s-1ENGINE\s0 \fBimpl\fR. \fBctx\fR must be initialized by calling
160\&\fIEVP_MD_CTX_init()\fR before calling this function.
984263bc 161.PP
8b0cefbb 162\&\fIEVP_VerifyUpdate()\fR hashes \fBcnt\fR bytes of data at \fBd\fR into the
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163verification context \fBctx\fR. This function can be called several times on the
164same \fBctx\fR to include additional data.
165.PP
8b0cefbb 166\&\fIEVP_VerifyFinal()\fR verifies the data in \fBctx\fR using the public key \fBpkey\fR
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167and against the \fBsiglen\fR bytes at \fBsigbuf\fR.
168.PP
8b0cefbb 169\&\fIEVP_VerifyInit()\fR initializes verification context \fBctx\fR to use the default
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170implementation of digest \fBtype\fR.
171.SH "RETURN VALUES"
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172.IX Header "RETURN VALUES"
173\&\fIEVP_VerifyInit_ex()\fR and \fIEVP_VerifyUpdate()\fR return 1 for success and 0 for
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174failure.
175.PP
8b0cefbb 176\&\fIEVP_VerifyFinal()\fR returns 1 for a correct signature, 0 for failure and \-1 if some
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177other error occurred.
178.PP
8b0cefbb 179The error codes can be obtained by \fIERR_get_error\fR\|(3).
984263bc 180.SH "NOTES"
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181.IX Header "NOTES"
182The \fB\s-1EVP\s0\fR interface to digital signatures should almost always be used in
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183preference to the low level interfaces. This is because the code then becomes
184transparent to the algorithm used and much more flexible.
185.PP
186Due to the link between message digests and public key algorithms the correct
187digest algorithm must be used with the correct public key type. A list of
188algorithms and associated public key algorithms appears in
8b0cefbb 189\&\fIEVP_DigestInit\fR\|(3).
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190.PP
191The call to \fIEVP_VerifyFinal()\fR internally finalizes a copy of the digest context.
192This means that calls to \fIEVP_VerifyUpdate()\fR and \fIEVP_VerifyFinal()\fR can be called
193later to digest and verify additional data.
194.PP
195Since only a copy of the digest context is ever finalized the context must
196be cleaned up after use by calling \fIEVP_MD_CTX_cleanup()\fR or a memory leak
197will occur.
198.SH "BUGS"
8b0cefbb 199.IX Header "BUGS"
984263bc 200Older versions of this documentation wrongly stated that calls to
8b0cefbb 201\&\fIEVP_VerifyUpdate()\fR could not be made after calling \fIEVP_VerifyFinal()\fR.
984263bc 202.SH "SEE ALSO"
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203.IX Header "SEE ALSO"
204\&\fIevp\fR\|(3),
205\&\fIEVP_SignInit\fR\|(3),
206\&\fIEVP_DigestInit\fR\|(3), \fIerr\fR\|(3),
207\&\fIevp\fR\|(3), \fIhmac\fR\|(3), \fImd2\fR\|(3),
208\&\fImd5\fR\|(3), \fImdc2\fR\|(3), \fIripemd\fR\|(3),
209\&\fIsha\fR\|(3), \fIdgst\fR\|(1)
984263bc 210.SH "HISTORY"
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211.IX Header "HISTORY"
212\&\fIEVP_VerifyInit()\fR, \fIEVP_VerifyUpdate()\fR and \fIEVP_VerifyFinal()\fR are
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213available in all versions of SSLeay and OpenSSL.
214.PP
8b0cefbb 215\&\fIEVP_VerifyInit_ex()\fR was added in OpenSSL 0.9.7