'\" te .\" Automatically generated by Pod::Man 2.23 (Pod::Simple 3.14) .\" .\" 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" EVP_PKEY_verify_recover_init, EVP_PKEY_verify_recover \- recover signature using a public key algorithm .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include \& \& int EVP_PKEY_verify_recover_init(EVP_PKEY_CTX *ctx); \& int EVP_PKEY_verify_recover(EVP_PKEY_CTX *ctx, \& unsigned char *rout, size_t *routlen, \& const unsigned char *sig, size_t siglen); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \fIEVP_PKEY_verify_recover_init()\fR function initializes a public key algorithm context using key \fBpkey\fR for a verify recover operation. .PP The \fIEVP_PKEY_verify_recover()\fR function recovers signed data using \fBctx\fR. The signature is specified using the \fBsig\fR and \&\fBsiglen\fR parameters. If \fBrout\fR is \fB\s-1NULL\s0\fR then the maximum size of the output buffer is written to the \fBroutlen\fR parameter. If \fBrout\fR is not \fB\s-1NULL\s0\fR then before the call the \fBroutlen\fR parameter should contain the length of the \&\fBrout\fR buffer, if the call is successful recovered data is written to \&\fBrout\fR and the amount of data written to \fBroutlen\fR. .\" Oracle has added the ARC stability level to this manual page .SH ATTRIBUTES See .BR attributes (5) for descriptions of the following attributes: .sp .TS box; cbp-1 | cbp-1 l | l . ATTRIBUTE TYPE ATTRIBUTE VALUE = Availability library/security/openssl = Stability Uncommitted .TE .PP .SH "NOTES" .IX Header "NOTES" Normally an application is only interested in whether a signature verification operation is successful in those cases the \fIEVP_verify()\fR function should be used. .PP Sometimes however it is useful to obtain the data originally signed using a signing operation. Only certain public key algorithms can recover a signature in this way (for example \s-1RSA\s0 in \s-1PKCS\s0 padding mode). .PP After the call to \fIEVP_PKEY_verify_recover_init()\fR algorithm specific control operations can be performed to set any appropriate parameters for the operation. .PP The function \fIEVP_PKEY_verify_recover()\fR can be called more than once on the same context if several operations are performed using the same parameters. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fIEVP_PKEY_verify_recover_init()\fR and \fIEVP_PKEY_verify_recover()\fR 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. .SH "EXAMPLE" .IX Header "EXAMPLE" Recover digest originally signed using PKCS#1 and \s-1SHA256\s0 digest: .PP .Vb 2 \& #include \& #include \& \& EVP_PKEY_CTX *ctx; \& unsigned char *rout, *sig; \& size_t routlen, siglen; \& EVP_PKEY *verify_key; \& /* NB: assumes verify_key, sig and siglen are already set up \& * and that verify_key is an RSA public key \& */ \& ctx = EVP_PKEY_CTX_new(verify_key); \& if (!ctx) \& /* Error occurred */ \& if (EVP_PKEY_verify_recover_init(ctx) <= 0) \& /* Error */ \& if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) \& /* Error */ \& if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) \& /* Error */ \& \& /* Determine buffer length */ \& if (EVP_PKEY_verify_recover(ctx, NULL, &routlen, sig, siglen) <= 0) \& /* Error */ \& \& rout = OPENSSL_malloc(routlen); \& \& if (!rout) \& /* malloc failure */ \& \& if (EVP_PKEY_verify_recover(ctx, rout, &routlen, sig, siglen) <= 0) \& /* Error */ \& \& /* Recovered data is routlen bytes written to buffer rout */ .Ve .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fIEVP_PKEY_CTX_new\fR\|(3), \&\fIEVP_PKEY_encrypt\fR\|(3), \&\fIEVP_PKEY_decrypt\fR\|(3), \&\fIEVP_PKEY_sign\fR\|(3), \&\fIEVP_PKEY_verify\fR\|(3), \&\fIEVP_PKEY_derive\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" These functions were first added to OpenSSL 1.0.0. .\" Oracle has added source availability information to this manual page This software was built from source available at https://java.net/projects/solaris-userland. The original community source was downloaded from http://www.openssl.org/source/openssl-1.0.1t.tar.gz Further information about this software can be found on the open source community website at http://www.openssl.org/.