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76 lines
2.4 KiB
76 lines
2.4 KiB
=pod |
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=head1 NAME |
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BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx - cipher BIO filter |
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=head1 SYNOPSIS |
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#include <openssl/bio.h> |
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#include <openssl/evp.h> |
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BIO_METHOD * BIO_f_cipher(void); |
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void BIO_set_cipher(BIO *b,const EVP_CIPHER *cipher, |
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unsigned char *key, unsigned char *iv, int enc); |
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int BIO_get_cipher_status(BIO *b) |
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int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx) |
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=head1 DESCRIPTION |
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BIO_f_cipher() returns the cipher BIO method. This is a filter |
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BIO that encrypts any data written through it, and decrypts any data |
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read from it. It is a BIO wrapper for the cipher routines |
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EVP_CipherInit(), EVP_CipherUpdate() and EVP_CipherFinal(). |
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Cipher BIOs do not support BIO_gets() or BIO_puts(). |
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BIO_flush() on an encryption BIO that is being written through is |
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used to signal that no more data is to be encrypted: this is used |
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to flush and possibly pad the final block through the BIO. |
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BIO_set_cipher() sets the cipher of BIO B<b> to B<cipher> using key B<key> |
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and IV B<iv>. B<enc> should be set to 1 for encryption and zero for |
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decryption. |
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When reading from an encryption BIO the final block is automatically |
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decrypted and checked when EOF is detected. BIO_get_cipher_status() |
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is a BIO_ctrl() macro which can be called to determine whether the |
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decryption operation was successful. |
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BIO_get_cipher_ctx() is a BIO_ctrl() macro which retrieves the internal |
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BIO cipher context. The retrieved context can be used in conjunction |
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with the standard cipher routines to set it up. This is useful when |
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BIO_set_cipher() is not flexible enough for the applications needs. |
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=head1 NOTES |
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When encrypting BIO_flush() B<must> be called to flush the final block |
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through the BIO. If it is not then the final block will fail a subsequent |
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decrypt. |
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When decrypting an error on the final block is signalled by a zero |
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return value from the read operation. A successful decrypt followed |
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by EOF will also return zero for the final read. BIO_get_cipher_status() |
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should be called to determine if the decrypt was successful. |
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As always, if BIO_gets() or BIO_puts() support is needed then it can |
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be achieved by preceding the cipher BIO with a buffering BIO. |
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=head1 RETURN VALUES |
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BIO_f_cipher() returns the cipher BIO method. |
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BIO_set_cipher() does not return a value. |
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BIO_get_cipher_status() returns 1 for a successful decrypt and 0 |
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for failure. |
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BIO_get_cipher_ctx() currently always returns 1. |
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=head1 EXAMPLES |
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TBA |
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=head1 SEE ALSO |
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TBA
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