Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / rc4.3
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124.\" ========================================================================
125.\"
126.IX Title "rc4 3"
e3261593 127.TH rc4 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 133RC4_set_key, RC4 \- RC4 encryption
984263bc 134.SH "SYNOPSIS"
8b0cefbb 135.IX Header "SYNOPSIS"
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136.Vb 1
137\& #include <openssl/rc4.h>
e257b235 138\&
984263bc 139\& void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);
e257b235 140\&
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141\& void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
142\& unsigned char *outdata);
143.Ve
144.SH "DESCRIPTION"
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145.IX Header "DESCRIPTION"
146This library implements the Alleged \s-1RC4\s0 cipher, which is described for
984263bc 147example in \fIApplied Cryptography\fR. It is believed to be compatible
8b0cefbb 148with RC4[\s-1TM\s0], a proprietary cipher of \s-1RSA\s0 Security Inc.
984263bc 149.PP
8b0cefbb 150\&\s-1RC4\s0 is a stream cipher with variable key length. Typically, 128 bit
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151(16 byte) keys are used for strong encryption, but shorter insecure
152key sizes have been widely used due to export restrictions.
153.PP
8b0cefbb 154\&\s-1RC4\s0 consists of a key setup phase and the actual encryption or
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155decryption phase.
156.PP
8b0cefbb 157\&\fIRC4_set_key()\fR sets up the \fB\s-1RC4_KEY\s0\fR \fBkey\fR using the \fBlen\fR bytes long
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158key at \fBdata\fR.
159.PP
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160\&\s-1\fIRC4\s0()\fR encrypts or decrypts the \fBlen\fR bytes of data at \fBindata\fR using
161\&\fBkey\fR and places the result at \fBoutdata\fR. Repeated \s-1\fIRC4\s0()\fR calls with
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162the same \fBkey\fR yield a continuous key stream.
163.PP
8b0cefbb 164Since \s-1RC4\s0 is a stream cipher (the input is XORed with a pseudo-random
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165key stream to produce the output), decryption uses the same function
166calls as encryption.
167.PP
168Applications should use the higher level functions
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169\&\fIEVP_EncryptInit\fR\|(3)
170etc. instead of calling the \s-1RC4\s0 functions directly.
984263bc 171.SH "RETURN VALUES"
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172.IX Header "RETURN VALUES"
173\&\fIRC4_set_key()\fR and \s-1\fIRC4\s0()\fR do not return values.
984263bc 174.SH "NOTE"
8b0cefbb 175.IX Header "NOTE"
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176Certain conditions have to be observed to securely use stream ciphers.
177It is not permissible to perform multiple encryptions using the same
178key stream.
179.SH "SEE ALSO"
74dab6c2 180.IX Header "SEE ALSO"
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181\&\fIblowfish\fR\|(3), \fIdes\fR\|(3), \fIrc2\fR\|(3)
182.SH "HISTORY"
984263bc 183.IX Header "HISTORY"
8b0cefbb 184\&\fIRC4_set_key()\fR and \s-1\fIRC4\s0()\fR are available in all versions of SSLeay and OpenSSL.