a528d4f0a9
If something was "present in all versions" of SSLeay, or if it was added to a version of SSLeay (and therefore predates OpenSSL), remove mention of it. Documentation history now starts with OpenSSL. Remove mention of all history before OpenSSL 0.9.8, inclusive. Remove all AUTHOR sections. Reviewed-by: Tim Hudson <tjh@openssl.org>
48 lines
1.3 KiB
Text
48 lines
1.3 KiB
Text
=pod
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=head1 NAME
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BN_CTX_start, BN_CTX_get, BN_CTX_end - use temporary BIGNUM variables
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=head1 SYNOPSIS
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#include <openssl/bn.h>
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void BN_CTX_start(BN_CTX *ctx);
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BIGNUM *BN_CTX_get(BN_CTX *ctx);
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void BN_CTX_end(BN_CTX *ctx);
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=head1 DESCRIPTION
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These functions are used to obtain temporary B<BIGNUM> variables from
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a B<BN_CTX> (which can been created by using L<BN_CTX_new(3)>)
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in order to save the overhead of repeatedly creating and
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freeing B<BIGNUM>s in functions that are called from inside a loop.
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A function must call BN_CTX_start() first. Then, BN_CTX_get() may be
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called repeatedly to obtain temporary B<BIGNUM>s. All BN_CTX_get()
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calls must be made before calling any other functions that use the
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B<ctx> as an argument.
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Finally, BN_CTX_end() must be called before returning from the function.
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When BN_CTX_end() is called, the B<BIGNUM> pointers obtained from
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BN_CTX_get() become invalid.
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=head1 RETURN VALUES
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BN_CTX_start() and BN_CTX_end() return no values.
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BN_CTX_get() returns a pointer to the B<BIGNUM>, or B<NULL> on error.
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Once BN_CTX_get() has failed, the subsequent calls will return B<NULL>
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as well, so it is sufficient to check the return value of the last
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BN_CTX_get() call. In case of an error, an error code is set, which
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can be obtained by L<ERR_get_error(3)>.
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=head1 SEE ALSO
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L<BN_CTX_new(3)>
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=cut
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