2000-02-05 10:41:05 +00:00
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=pod
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=head1 NAME
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RC4_set_key, RC4 - RC4 encryption
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=head1 SYNOPSIS
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#include <openssl/rc4.h>
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void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);
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void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
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unsigned char *outdata);
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=head1 DESCRIPTION
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This library implements the Alleged RC4 cipher, which is described for
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example in I<Applied Cryptography>. It is believed to be compatible
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with RC4[TM], a proprietary cipher of RSA Security Inc.
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RC4 is a stream cipher with variable key length. Typically, 128 bit
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(16 byte) keys are used for strong encryption, but shorter insecure
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key sizes have been widely used due to export restrictions.
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RC4 consists of a key setup phase and the actual encryption or
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decryption phase.
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RC4_set_key() sets up the B<RC4_KEY> B<key> using the B<len> bytes long
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key at B<data>.
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RC4() encrypts or decrypts the B<len> bytes of data at B<indata> using
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B<key> and places the result at B<outdata>. Repeated RC4() calls with
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the same B<key> yield a continuous key stream.
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Since RC4 is a stream cipher (the input is XORed with a pseudo-random
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key stream to produce the output), decryption uses the same function
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calls as encryption.
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2000-02-25 16:00:24 +00:00
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Applications should use the higher level functions
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L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>
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2000-02-24 11:55:57 +00:00
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etc. instead of calling the RC4 functions directly.
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2000-02-05 10:41:05 +00:00
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=head1 RETURN VALUES
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RC4_set_key() and RC4() do not return values.
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=head1 NOTE
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Certain conditions have to be observed to securely use stream ciphers.
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It is not permissible to perform multiple encryptions using the same
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key stream.
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=head1 SEE ALSO
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L<blowfish(3)|blowfish(3)>, L<des(3)|des(3)>, L<rc2(3)|rc2(3)>
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=head1 HISTORY
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RC4_set_key() and RC4() are available in all versions of SSLeay and OpenSSL.
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=cut
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