69 lines
2 KiB
Text
69 lines
2 KiB
Text
=pod
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=head1 NAME
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RSA_private_encrypt, RSA_public_decrypt - low level signature operations
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=head1 SYNOPSIS
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#include <openssl/rsa.h>
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int RSA_private_encrypt(int flen, unsigned char *from,
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unsigned char *to, RSA *rsa, int padding);
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int RSA_public_decrypt(int flen, unsigned char *from,
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unsigned char *to, RSA *rsa, int padding);
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=head1 DESCRIPTION
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These functions handle RSA signatures at a low level.
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RSA_private_encrypt() signs the B<flen> bytes at B<from> (usually a
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message digest with an algorithm identifier) using the private key
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B<rsa> and stores the signature in B<to>. B<to> must point to
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B<RSA_size(rsa)> bytes of memory.
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B<padding> denotes one of the following modes:
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=over 4
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=item RSA_PKCS1_PADDING
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PKCS #1 v1.5 padding. This function does not handle the
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B<algorithmIdentifier> specified in PKCS #1. When generating or
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verifying PKCS #1 signatures, L<RSA_sign(3)|RSA_sign(3)> and L<RSA_verify(3)|RSA_verify(3)> should be
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used.
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=item RSA_NO_PADDING
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Raw RSA signature. This mode should I<only> be used to implement
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cryptographically sound padding modes in the application code.
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Signing user data directly with RSA is insecure.
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=back
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RSA_public_decrypt() recovers the message digest from the B<flen>
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bytes long signature at B<from> using the signer's public key
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B<rsa>. B<to> must point to a memory section large enough to hold the
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message digest (which is smaller than B<RSA_size(rsa) -
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11>). B<padding> is the padding mode that was used to sign the data.
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=head1 RETURN VALUES
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RSA_private_encrypt() returns the size of the signature (i.e.,
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RSA_size(rsa)). RSA_public_decrypt() returns the size of the
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recovered message digest.
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On error, -1 is returned; the error codes can be
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obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
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=head1 SEE ALSO
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L<err(3)|err(3)>, L<rsa(3)|rsa(3)>, L<RSA_sign(3)|RSA_sign(3)>, L<RSA_verify(3)|RSA_verify(3)>
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=head1 HISTORY
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The B<padding> argument was added in SSLeay 0.8. RSA_NO_PADDING is
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available since SSLeay 0.9.0.
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=cut
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