Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / BIO_f_cipher.3
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124.\" ========================================================================
125.\"
126.IX Title "BIO_f_cipher 3"
e3261593 127.TH BIO_f_cipher 3 "2012-01-04" "1.0.0f" "OpenSSL"
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128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
984263bc 132.SH "NAME"
74dab6c2 133BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx \- cipher BIO filter
984263bc 134.SH "SYNOPSIS"
8b0cefbb 135.IX Header "SYNOPSIS"
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136.Vb 2
137\& #include <openssl/bio.h>
138\& #include <openssl/evp.h>
e257b235 139\&
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140\& BIO_METHOD * BIO_f_cipher(void);
141\& void BIO_set_cipher(BIO *b,const EVP_CIPHER *cipher,
142\& unsigned char *key, unsigned char *iv, int enc);
143\& int BIO_get_cipher_status(BIO *b)
144\& int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx)
145.Ve
146.SH "DESCRIPTION"
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147.IX Header "DESCRIPTION"
148\&\fIBIO_f_cipher()\fR returns the cipher \s-1BIO\s0 method. This is a filter
149\&\s-1BIO\s0 that encrypts any data written through it, and decrypts any data
150read from it. It is a \s-1BIO\s0 wrapper for the cipher routines
151\&\fIEVP_CipherInit()\fR, \fIEVP_CipherUpdate()\fR and \fIEVP_CipherFinal()\fR.
984263bc 152.PP
e257b235 153Cipher BIOs do not support \fIBIO_gets()\fR or \fIBIO_puts()\fR.
984263bc 154.PP
8b0cefbb 155\&\fIBIO_flush()\fR on an encryption \s-1BIO\s0 that is being written through is
984263bc 156used to signal that no more data is to be encrypted: this is used
8b0cefbb 157to flush and possibly pad the final block through the \s-1BIO\s0.
984263bc 158.PP
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159\&\fIBIO_set_cipher()\fR sets the cipher of \s-1BIO\s0 \fBb\fR to \fBcipher\fR using key \fBkey\fR
160and \s-1IV\s0 \fBiv\fR. \fBenc\fR should be set to 1 for encryption and zero for
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161decryption.
162.PP
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163When reading from an encryption \s-1BIO\s0 the final block is automatically
164decrypted and checked when \s-1EOF\s0 is detected. \fIBIO_get_cipher_status()\fR
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165is a \fIBIO_ctrl()\fR macro which can be called to determine whether the
166decryption operation was successful.
167.PP
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168\&\fIBIO_get_cipher_ctx()\fR is a \fIBIO_ctrl()\fR macro which retrieves the internal
169\&\s-1BIO\s0 cipher context. The retrieved context can be used in conjunction
984263bc 170with the standard cipher routines to set it up. This is useful when
8b0cefbb 171\&\fIBIO_set_cipher()\fR is not flexible enough for the applications needs.
984263bc 172.SH "NOTES"
8b0cefbb 173.IX Header "NOTES"
984263bc 174When encrypting \fIBIO_flush()\fR \fBmust\fR be called to flush the final block
8b0cefbb 175through the \s-1BIO\s0. If it is not then the final block will fail a subsequent
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176decrypt.
177.PP
178When decrypting an error on the final block is signalled by a zero
179return value from the read operation. A successful decrypt followed
8b0cefbb 180by \s-1EOF\s0 will also return zero for the final read. \fIBIO_get_cipher_status()\fR
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181should be called to determine if the decrypt was successful.
182.PP
183As always, if \fIBIO_gets()\fR or \fIBIO_puts()\fR support is needed then it can
8b0cefbb 184be achieved by preceding the cipher \s-1BIO\s0 with a buffering \s-1BIO\s0.
984263bc 185.SH "RETURN VALUES"
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186.IX Header "RETURN VALUES"
187\&\fIBIO_f_cipher()\fR returns the cipher \s-1BIO\s0 method.
984263bc 188.PP
8b0cefbb 189\&\fIBIO_set_cipher()\fR does not return a value.
984263bc 190.PP
8b0cefbb 191\&\fIBIO_get_cipher_status()\fR returns 1 for a successful decrypt and 0
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192for failure.
193.PP
8b0cefbb 194\&\fIBIO_get_cipher_ctx()\fR currently always returns 1.
984263bc 195.SH "EXAMPLES"
74dab6c2 196.IX Header "EXAMPLES"
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197\&\s-1TBA\s0
198.SH "SEE ALSO"
984263bc 199.IX Header "SEE ALSO"
8b0cefbb 200\&\s-1TBA\s0