- update OpenSSL to 0.9.8
[dragonfly.git] / secure / lib / libcrypto / man / BIO_f_cipher.3
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129.\" ========================================================================
130.\"
131.IX Title "BIO_f_cipher 3"
a561f9ff 132.TH BIO_f_cipher 3 "2005-07-06" "0.9.8" "OpenSSL"
984263bc 133.SH "NAME"
74dab6c2 134BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx \- cipher BIO filter
984263bc 135.SH "SYNOPSIS"
8b0cefbb 136.IX Header "SYNOPSIS"
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137.Vb 2
138\& #include <openssl/bio.h>
139\& #include <openssl/evp.h>
140.Ve
8b0cefbb 141.PP
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142.Vb 5
143\& BIO_METHOD * BIO_f_cipher(void);
144\& void BIO_set_cipher(BIO *b,const EVP_CIPHER *cipher,
145\& unsigned char *key, unsigned char *iv, int enc);
146\& int BIO_get_cipher_status(BIO *b)
147\& int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx)
148.Ve
149.SH "DESCRIPTION"
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150.IX Header "DESCRIPTION"
151\&\fIBIO_f_cipher()\fR returns the cipher \s-1BIO\s0 method. This is a filter
152\&\s-1BIO\s0 that encrypts any data written through it, and decrypts any data
153read from it. It is a \s-1BIO\s0 wrapper for the cipher routines
154\&\fIEVP_CipherInit()\fR, \fIEVP_CipherUpdate()\fR and \fIEVP_CipherFinal()\fR.
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155.PP
156Cipher BIOs do not support \fIBIO_gets()\fR or \fIBIO_puts()\fR.
157.PP
8b0cefbb 158\&\fIBIO_flush()\fR on an encryption \s-1BIO\s0 that is being written through is
984263bc 159used to signal that no more data is to be encrypted: this is used
8b0cefbb 160to flush and possibly pad the final block through the \s-1BIO\s0.
984263bc 161.PP
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162\&\fIBIO_set_cipher()\fR sets the cipher of \s-1BIO\s0 \fBb\fR to \fBcipher\fR using key \fBkey\fR
163and \s-1IV\s0 \fBiv\fR. \fBenc\fR should be set to 1 for encryption and zero for
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164decryption.
165.PP
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166When reading from an encryption \s-1BIO\s0 the final block is automatically
167decrypted and checked when \s-1EOF\s0 is detected. \fIBIO_get_cipher_status()\fR
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168is a \fIBIO_ctrl()\fR macro which can be called to determine whether the
169decryption operation was successful.
170.PP
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171\&\fIBIO_get_cipher_ctx()\fR is a \fIBIO_ctrl()\fR macro which retrieves the internal
172\&\s-1BIO\s0 cipher context. The retrieved context can be used in conjunction
984263bc 173with the standard cipher routines to set it up. This is useful when
8b0cefbb 174\&\fIBIO_set_cipher()\fR is not flexible enough for the applications needs.
984263bc 175.SH "NOTES"
8b0cefbb 176.IX Header "NOTES"
984263bc 177When encrypting \fIBIO_flush()\fR \fBmust\fR be called to flush the final block
8b0cefbb 178through the \s-1BIO\s0. If it is not then the final block will fail a subsequent
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179decrypt.
180.PP
181When decrypting an error on the final block is signalled by a zero
182return value from the read operation. A successful decrypt followed
8b0cefbb 183by \s-1EOF\s0 will also return zero for the final read. \fIBIO_get_cipher_status()\fR
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184should be called to determine if the decrypt was successful.
185.PP
186As always, if \fIBIO_gets()\fR or \fIBIO_puts()\fR support is needed then it can
8b0cefbb 187be achieved by preceding the cipher \s-1BIO\s0 with a buffering \s-1BIO\s0.
984263bc 188.SH "RETURN VALUES"
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189.IX Header "RETURN VALUES"
190\&\fIBIO_f_cipher()\fR returns the cipher \s-1BIO\s0 method.
984263bc 191.PP
8b0cefbb 192\&\fIBIO_set_cipher()\fR does not return a value.
984263bc 193.PP
8b0cefbb 194\&\fIBIO_get_cipher_status()\fR returns 1 for a successful decrypt and 0
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195for failure.
196.PP
8b0cefbb 197\&\fIBIO_get_cipher_ctx()\fR currently always returns 1.
984263bc 198.SH "EXAMPLES"
74dab6c2 199.IX Header "EXAMPLES"
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200\&\s-1TBA\s0
201.SH "SEE ALSO"
984263bc 202.IX Header "SEE ALSO"
8b0cefbb 203\&\s-1TBA\s0