Regenerate the manual pages after the OpenSSL update to 0.9.7e.
[dragonfly.git] / secure / lib / libcrypto / man / EVP_SealInit.3
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129.\" ========================================================================
130.\"
131.IX Title "EVP_SealInit 3"
132.TH EVP_SealInit 3 "2004-12-18" "0.9.7e" "OpenSSL"
984263bc 133.SH "NAME"
74dab6c2 134EVP_SealInit, EVP_SealUpdate, EVP_SealFinal \- EVP envelope encryption
984263bc 135.SH "SYNOPSIS"
8b0cefbb 136.IX Header "SYNOPSIS"
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137.Vb 1
138\& #include <openssl/evp.h>
139.Ve
8b0cefbb 140.PP
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141.Vb 6
142\& int EVP_SealInit(EVP_CIPHER_CTX *ctx, EVP_CIPHER *type, unsigned char **ek,
143\& int *ekl, unsigned char *iv,EVP_PKEY **pubk, int npubk);
144\& int EVP_SealUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
145\& int *outl, unsigned char *in, int inl);
146\& int EVP_SealFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
147\& int *outl);
148.Ve
149.SH "DESCRIPTION"
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150.IX Header "DESCRIPTION"
151The \s-1EVP\s0 envelope routines are a high level interface to envelope
152encryption. They generate a random key and \s-1IV\s0 (if required) then
153\&\*(L"envelope\*(R" it by using public key encryption. Data can then be
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154encrypted using this key.
155.PP
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156\&\fIEVP_SealInit()\fR initializes a cipher context \fBctx\fR for encryption
157with cipher \fBtype\fR using a random secret key and \s-1IV\s0. \fBtype\fR is normally
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158supplied by a function such as \fIEVP_des_cbc()\fR. The secret key is encrypted
159using one or more public keys, this allows the same encrypted data to be
160decrypted using any of the corresponding private keys. \fBek\fR is an array of
161buffers where the public key encrypted secret key will be written, each buffer
162must contain enough room for the corresponding encrypted key: that is
8b0cefbb 163\&\fBek[i]\fR must have room for \fBEVP_PKEY_size(pubk[i])\fR bytes. The actual
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164size of each encrypted secret key is written to the array \fBekl\fR. \fBpubk\fR is
165an array of \fBnpubk\fR public keys.
166.PP
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167The \fBiv\fR parameter is a buffer where the generated \s-1IV\s0 is written to. It must
168contain enough room for the corresponding cipher's \s-1IV\s0, as determined by (for
169example) EVP_CIPHER_iv_length(type).
984263bc 170.PP
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171If the cipher does not require an \s-1IV\s0 then the \fBiv\fR parameter is ignored
172and can be \fB\s-1NULL\s0\fR.
984263bc 173.PP
8b0cefbb 174\&\fIEVP_SealUpdate()\fR and \fIEVP_SealFinal()\fR have exactly the same properties
984263bc 175as the \fIEVP_EncryptUpdate()\fR and \fIEVP_EncryptFinal()\fR routines, as
8b0cefbb 176documented on the \fIEVP_EncryptInit\fR\|(3) manual
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177page.
178.SH "RETURN VALUES"
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179.IX Header "RETURN VALUES"
180\&\fIEVP_SealInit()\fR returns 0 on error or \fBnpubk\fR if successful.
984263bc 181.PP
8b0cefbb 182\&\fIEVP_SealUpdate()\fR and \fIEVP_SealFinal()\fR return 1 for success and 0 for
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183failure.
184.SH "NOTES"
8b0cefbb 185.IX Header "NOTES"
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186Because a random secret key is generated the random number generator
187must be seeded before calling \fIEVP_SealInit()\fR.
188.PP
8b0cefbb 189The public key must be \s-1RSA\s0 because it is the only OpenSSL public key
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190algorithm that supports key transport.
191.PP
192Envelope encryption is the usual method of using public key encryption
193on large amounts of data, this is because public key encryption is slow
194but symmetric encryption is fast. So symmetric encryption is used for
195bulk encryption and the small random symmetric key used is transferred
196using public key encryption.
197.PP
198It is possible to call \fIEVP_SealInit()\fR twice in the same way as
8b0cefbb 199\&\fIEVP_EncryptInit()\fR. The first call should have \fBnpubk\fR set to 0
984263bc 200and (after setting any cipher parameters) it should be called again
8b0cefbb 201with \fBtype\fR set to \s-1NULL\s0.
984263bc 202.SH "SEE ALSO"
74dab6c2 203.IX Header "SEE ALSO"
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204\&\fIevp\fR\|(3), \fIrand\fR\|(3),
205\&\fIEVP_EncryptInit\fR\|(3),
206\&\fIEVP_OpenInit\fR\|(3)
207.SH "HISTORY"
984263bc 208.IX Header "HISTORY"
8b0cefbb 209\&\fIEVP_SealFinal()\fR did not return a value before OpenSSL 0.9.7.