491 lines
22 KiB
Groff
491 lines
22 KiB
Groff
.\" $NetBSD: EVP_EncryptInit.3,v 1.11 2002/08/09 16:15:39 itojun Exp $
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.\" ======================================================================
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.\"
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.IX Title "EVP_EncryptInit 3"
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.TH EVP_EncryptInit 3 "0.9.6g" "2002-06-10" "OpenSSL"
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.UC
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.SH "NAME"
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EVP_EncryptInit, EVP_EncryptUpdate, EVP_EncryptFinal, EVP_DecryptInit,
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EVP_DecryptUpdate, EVP_DecryptFinal, EVP_CipherInit, EVP_CipherUpdate,
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EVP_CipherFinal, EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl,
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EVP_CIPHER_CTX_cleanup, EVP_get_cipherbyname, EVP_get_cipherbynid,
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EVP_get_cipherbyobj, EVP_CIPHER_nid, EVP_CIPHER_block_size,
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EVP_CIPHER_key_length, EVP_CIPHER_iv_length, EVP_CIPHER_flags,
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EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher, EVP_CIPHER_CTX_nid,
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EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length, EVP_CIPHER_CTX_iv_length,
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EVP_CIPHER_CTX_get_app_data, EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type,
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EVP_CIPHER_CTX_flags, EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1,
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EVP_CIPHER_asn1_to_param \- \s-1EVP\s0 cipher routines
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.SH "LIBRARY"
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libcrypto, -lcrypto
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.SH "SYNOPSIS"
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.IX Header "SYNOPSIS"
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.Vb 1
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\& #include <openssl/evp.h>
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.Ve
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.Vb 6
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\& int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
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\& unsigned char *key, unsigned char *iv);
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\& int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
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\& int *outl, unsigned char *in, int inl);
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\& int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
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\& int *outl);
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.Ve
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.Vb 6
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\& int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
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\& unsigned char *key, unsigned char *iv);
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\& int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
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\& int *outl, unsigned char *in, int inl);
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\& int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
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\& int *outl);
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.Ve
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.Vb 6
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\& int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
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\& unsigned char *key, unsigned char *iv, int enc);
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\& int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
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\& int *outl, unsigned char *in, int inl);
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\& int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
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\& int *outl);
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.Ve
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.Vb 3
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\& int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
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\& int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
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\& int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
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.Ve
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.Vb 3
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\& const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
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\& #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
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\& #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
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.Ve
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.Vb 7
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\& #define EVP_CIPHER_nid(e) ((e)->nid)
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\& #define EVP_CIPHER_block_size(e) ((e)->block_size)
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\& #define EVP_CIPHER_key_length(e) ((e)->key_len)
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\& #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
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\& #define EVP_CIPHER_flags(e) ((e)->flags)
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\& #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE)
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\& int EVP_CIPHER_type(const EVP_CIPHER *ctx);
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.Ve
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.Vb 10
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\& #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher)
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\& #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid)
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\& #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size)
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\& #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len)
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\& #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len)
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\& #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
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\& #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d))
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\& #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
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\& #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags)
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\& #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE)
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.Ve
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.Vb 2
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\& int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
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\& int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
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.Ve
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.SH "DESCRIPTION"
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.IX Header "DESCRIPTION"
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The \s-1EVP\s0 cipher routines are a high level interface to certain
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symmetric ciphers.
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.PP
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\&\fIEVP_EncryptInit()\fR initializes a cipher context \fBctx\fR for encryption
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with cipher \fBtype\fR. \fBtype\fR is normally supplied by a function such
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as \fIEVP_des_cbc()\fR . \fBkey\fR is the symmetric key to use and \fBiv\fR is the
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\&\s-1IV\s0 to use (if necessary), the actual number of bytes used for the
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key and \s-1IV\s0 depends on the cipher. It is possible to set all parameters
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to \s-1NULL\s0 except \fBtype\fR in an initial call and supply the remaining
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parameters in subsequent calls, all of which have \fBtype\fR set to \s-1NULL\s0.
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This is done when the default cipher parameters are not appropriate.
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.PP
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\&\fIEVP_EncryptUpdate()\fR encrypts \fBinl\fR bytes from the buffer \fBin\fR and
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writes the encrypted version to \fBout\fR. This function can be called
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multiple times to encrypt successive blocks of data. The amount
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of data written depends on the block alignment of the encrypted data:
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as a result the amount of data written may be anything from zero bytes
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to (inl + cipher_block_size \- 1) so \fBoutl\fR should contain sufficient
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room. The actual number of bytes written is placed in \fBoutl\fR.
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.PP
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\&\fIEVP_EncryptFinal()\fR encrypts the \*(L"final\*(R" data, that is any data that
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remains in a partial block. It uses standard block padding (aka \s-1PKCS\s0
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padding). The encrypted final data is written to \fBout\fR which should
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have sufficient space for one cipher block. The number of bytes written
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is placed in \fBoutl\fR. After this function is called the encryption operation
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is finished and no further calls to \fIEVP_EncryptUpdate()\fR should be made.
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.PP
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\&\fIEVP_DecryptInit()\fR, \fIEVP_DecryptUpdate()\fR and \fIEVP_DecryptFinal()\fR are the
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corresponding decryption operations. \fIEVP_DecryptFinal()\fR will return an
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error code if the final block is not correctly formatted. The parameters
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and restrictions are identical to the encryption operations except that
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the decrypted data buffer \fBout\fR passed to \fIEVP_DecryptUpdate()\fR should
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have sufficient room for (\fBinl\fR + cipher_block_size) bytes unless the
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cipher block size is 1 in which case \fBinl\fR bytes is sufficient.
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.PP
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\&\fIEVP_CipherInit()\fR, \fIEVP_CipherUpdate()\fR and \fIEVP_CipherFinal()\fR are functions
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that can be used for decryption or encryption. The operation performed
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depends on the value of the \fBenc\fR parameter. It should be set to 1 for
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encryption, 0 for decryption and \-1 to leave the value unchanged (the
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actual value of 'enc' being supplied in a previous call).
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.PP
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\&\fIEVP_CIPHER_CTX_cleanup()\fR clears all information from a cipher context.
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It should be called after all operations using a cipher are complete
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so sensitive information does not remain in memory.
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.PP
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\&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
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return an \s-1EVP_CIPHER\s0 structure when passed a cipher name, a \s-1NID\s0 or an
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\&\s-1ASN1_OBJECT\s0 structure.
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.PP
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\&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return the \s-1NID\s0 of a cipher when
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passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR structure. The actual \s-1NID\s0
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value is an internal value which may not have a corresponding \s-1OBJECT\s0
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\&\s-1IDENTIFIER\s0.
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.PP
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\&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
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length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
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structure. The constant \fB\s-1EVP_MAX_KEY_LENGTH\s0\fR is the maximum key length
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for all ciphers. Note: although \fIEVP_CIPHER_key_length()\fR is fixed for a
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given cipher, the value of \fIEVP_CIPHER_CTX_key_length()\fR may be different
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for variable key length ciphers.
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.PP
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\&\fIEVP_CIPHER_CTX_set_key_length()\fR sets the key length of the cipher ctx.
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If the cipher is a fixed length cipher then attempting to set the key
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length to any value other than the fixed value is an error.
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.PP
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\&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
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length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR.
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It will return zero if the cipher does not use an \s-1IV\s0. The constant
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\&\fB\s-1EVP_MAX_IV_LENGTH\s0\fR is the maximum \s-1IV\s0 length for all ciphers.
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.PP
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\&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
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size of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
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structure. The constant \fB\s-1EVP_MAX_IV_LENGTH\s0\fR is also the maximum block
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length for all ciphers.
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.PP
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\&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the type of the passed
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cipher or context. This \*(L"type\*(R" is the actual \s-1NID\s0 of the cipher \s-1OBJECT\s0
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\&\s-1IDENTIFIER\s0 as such it ignores the cipher parameters and 40 bit \s-1RC2\s0 and
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128 bit \s-1RC2\s0 have the same \s-1NID\s0. If the cipher does not have an object
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identifier or does not have \s-1ASN1\s0 support this function will return
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\&\fBNID_undef\fR.
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.PP
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\&\fIEVP_CIPHER_CTX_cipher()\fR returns the \fB\s-1EVP_CIPHER\s0\fR structure when passed
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an \fB\s-1EVP_CIPHER_CTX\s0\fR structure.
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.PP
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\&\fIEVP_CIPHER_mode()\fR and \fIEVP_CIPHER_CTX_mode()\fR return the block cipher mode:
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\&\s-1EVP_CIPH_ECB_MODE\s0, \s-1EVP_CIPH_CBC_MODE\s0, \s-1EVP_CIPH_CFB_MODE\s0 or
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\&\s-1EVP_CIPH_OFB_MODE\s0. If the cipher is a stream cipher then
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\&\s-1EVP_CIPH_STREAM_CIPHER\s0 is returned.
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.PP
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\&\fIEVP_CIPHER_param_to_asn1()\fR sets the AlgorithmIdentifier \*(L"parameter\*(R" based
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on the passed cipher. This will typically include any parameters and an
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\&\s-1IV\s0. The cipher \s-1IV\s0 (if any) must be set when this call is made. This call
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should be made before the cipher is actually \*(L"used\*(R" (before any
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\&\fIEVP_EncryptUpdate()\fR, \fIEVP_DecryptUpdate()\fR calls for example). This function
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may fail if the cipher does not have any \s-1ASN1\s0 support.
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.PP
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\&\fIEVP_CIPHER_asn1_to_param()\fR sets the cipher parameters based on an \s-1ASN1\s0
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AlgorithmIdentifier \*(L"parameter\*(R". The precise effect depends on the cipher
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In the case of \s-1RC2\s0, for example, it will set the \s-1IV\s0 and effective key length.
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This function should be called after the base cipher type is set but before
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the key is set. For example \fIEVP_CipherInit()\fR will be called with the \s-1IV\s0 and
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key set to \s-1NULL\s0, \fIEVP_CIPHER_asn1_to_param()\fR will be called and finally
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\&\fIEVP_CipherInit()\fR again with all parameters except the key set to \s-1NULL\s0. It is
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possible for this function to fail if the cipher does not have any \s-1ASN1\s0 support
|
|
or the parameters cannot be set (for example the \s-1RC2\s0 effective key length
|
|
is not supported.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_ctrl()\fR allows various cipher specific parameters to be determined
|
|
and set. Currently only the \s-1RC2\s0 effective key length and the number of rounds of
|
|
\&\s-1RC5\s0 can be set.
|
|
.SH "RETURN VALUES"
|
|
.IX Header "RETURN VALUES"
|
|
\&\fIEVP_EncryptInit()\fR, \fIEVP_EncryptUpdate()\fR and \fIEVP_EncryptFinal()\fR return 1 for success
|
|
and 0 for failure.
|
|
.PP
|
|
\&\fIEVP_DecryptInit()\fR and \fIEVP_DecryptUpdate()\fR return 1 for success and 0 for failure.
|
|
\&\fIEVP_DecryptFinal()\fR returns 0 if the decrypt failed or 1 for success.
|
|
.PP
|
|
\&\fIEVP_CipherInit()\fR and \fIEVP_CipherUpdate()\fR return 1 for success and 0 for failure.
|
|
\&\fIEVP_CipherFinal()\fR returns 0 for a decryption failure or 1 for success.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_cleanup()\fR returns 1 for success and 0 for failure.
|
|
.PP
|
|
\&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
|
|
return an \fB\s-1EVP_CIPHER\s0\fR structure or \s-1NULL\s0 on error.
|
|
.PP
|
|
\&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return a \s-1NID\s0.
|
|
.PP
|
|
\&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
|
|
size.
|
|
.PP
|
|
\&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
|
|
length.
|
|
.PP
|
|
\&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
|
|
length or zero if the cipher does not use an \s-1IV\s0.
|
|
.PP
|
|
\&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the \s-1NID\s0 of the cipher's
|
|
\&\s-1OBJECT\s0 \s-1IDENTIFIER\s0 or NID_undef if it has no defined \s-1OBJECT\s0 \s-1IDENTIFIER\s0.
|
|
.PP
|
|
\&\fIEVP_CIPHER_CTX_cipher()\fR returns an \fB\s-1EVP_CIPHER\s0\fR structure.
|
|
.PP
|
|
\&\fIEVP_CIPHER_param_to_asn1()\fR and \fIEVP_CIPHER_asn1_to_param()\fR return 1 for
|
|
success or zero for failure.
|
|
.SH "CIPHER LISTING"
|
|
.IX Header "CIPHER LISTING"
|
|
All algorithms have a fixed key length unless otherwise stated.
|
|
.Ip "\fIEVP_enc_null()\fR" 4
|
|
.IX Item "EVP_enc_null()"
|
|
Null cipher: does nothing.
|
|
.Ip "EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)" 4
|
|
.IX Item "EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)"
|
|
\&\s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
|
|
.Ip "EVP_des_ede_cbc(void), \fIEVP_des_ede()\fR, EVP_des_ede_ofb(void), EVP_des_ede_cfb(void)" 4
|
|
.IX Item "EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void), EVP_des_ede_cfb(void)"
|
|
Two key triple \s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
|
|
.Ip "EVP_des_ede3_cbc(void), \fIEVP_des_ede3()\fR, EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void)" 4
|
|
.IX Item "EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void)"
|
|
Three key triple \s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
|
|
.Ip "EVP_desx_cbc(void)" 4
|
|
.IX Item "EVP_desx_cbc(void)"
|
|
\&\s-1DESX\s0 algorithm in \s-1CBC\s0 mode.
|
|
.Ip "EVP_rc4(void)" 4
|
|
.IX Item "EVP_rc4(void)"
|
|
\&\s-1RC4\s0 stream cipher. This is a variable key length cipher with default key length 128 bits.
|
|
.Ip "EVP_rc4_40(void)" 4
|
|
.IX Item "EVP_rc4_40(void)"
|
|
\&\s-1RC4\s0 stream cipher with 40 bit key length. This is obsolete and new code should use \fIEVP_rc4()\fR
|
|
and the \fIEVP_CIPHER_CTX_set_key_length()\fR function.
|
|
.Ip "\fIEVP_idea_cbc()\fR EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)" 4
|
|
.IX Item "EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)"
|
|
\&\s-1IDEA\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
|
|
.Ip "EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void)" 4
|
|
.IX Item "EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void)"
|
|
\&\s-1RC2\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
|
|
length cipher with an additional parameter called \*(L"effective key bits\*(R" or \*(L"effective key length\*(R".
|
|
By default both are set to 128 bits.
|
|
.Ip "EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)" 4
|
|
.IX Item "EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)"
|
|
\&\s-1RC2\s0 algorithm in \s-1CBC\s0 mode with a default key length and effective key length of 40 and 64 bits.
|
|
These are obsolete and new code should use \fIEVP_rc2_cbc()\fR, \fIEVP_CIPHER_CTX_set_key_length()\fR and
|
|
\&\fIEVP_CIPHER_CTX_ctrl()\fR to set the key length and effective key length.
|
|
.Ip "EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);" 4
|
|
.IX Item "EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);"
|
|
Blowfish encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
|
|
length cipher.
|
|
.Ip "EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void)" 4
|
|
.IX Item "EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void)"
|
|
\&\s-1CAST\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
|
|
length cipher.
|
|
.Ip "EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)" 4
|
|
.IX Item "EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)"
|
|
\&\s-1RC5\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key length
|
|
cipher with an additional \*(L"number of rounds\*(R" parameter. By default the key length is set to 128
|
|
bits and 12 rounds.
|
|
.SH "NOTES"
|
|
.IX Header "NOTES"
|
|
Where possible the \fB\s-1EVP\s0\fR interface to symmetric ciphers should be used in
|
|
preference to the low level interfaces. This is because the code then becomes
|
|
transparent to the cipher used and much more flexible.
|
|
.PP
|
|
\&\s-1PKCS\s0 padding works by adding \fBn\fR padding bytes of value \fBn\fR to make the total
|
|
length of the encrypted data a multiple of the block size. Padding is always
|
|
added so if the data is already a multiple of the block size \fBn\fR will equal
|
|
the block size. For example if the block size is 8 and 11 bytes are to be
|
|
encrypted then 5 padding bytes of value 5 will be added.
|
|
.PP
|
|
When decrypting the final block is checked to see if it has the correct form.
|
|
.PP
|
|
Although the decryption operation can produce an error, it is not a strong
|
|
test that the input data or key is correct. A random block has better than
|
|
1 in 256 chance of being of the correct format and problems with the
|
|
input data earlier on will not produce a final decrypt error.
|
|
.PP
|
|
The functions \fIEVP_EncryptInit()\fR, \fIEVP_EncryptUpdate()\fR, \fIEVP_EncryptFinal()\fR,
|
|
\&\fIEVP_DecryptInit()\fR, \fIEVP_DecryptUpdate()\fR, \fIEVP_CipherInit()\fR and \fIEVP_CipherUpdate()\fR
|
|
and \fIEVP_CIPHER_CTX_cleanup()\fR did not return errors in OpenSSL version 0.9.5a or
|
|
earlier. Software only versions of encryption algorithms will never return
|
|
error codes for these functions, unless there is a programming error (for example
|
|
and attempt to set the key before the cipher is set in \fIEVP_EncryptInit()\fR ).
|
|
.SH "BUGS"
|
|
.IX Header "BUGS"
|
|
For \s-1RC5\s0 the number of rounds can currently only be set to 8, 12 or 16. This is
|
|
a limitation of the current \s-1RC5\s0 code rather than the \s-1EVP\s0 interface.
|
|
.PP
|
|
It should be possible to disable \s-1PKCS\s0 padding: currently it isn't.
|
|
.PP
|
|
\&\s-1EVP_MAX_KEY_LENGTH\s0 and \s-1EVP_MAX_IV_LENGTH\s0 only refer to the internal ciphers with
|
|
default key lengths. If custom ciphers exceed these values the results are
|
|
unpredictable. This is because it has become standard practice to define a
|
|
generic key as a fixed unsigned char array containing \s-1EVP_MAX_KEY_LENGTH\s0 bytes.
|
|
.PP
|
|
The \s-1ASN1\s0 code is incomplete (and sometimes inaccurate) it has only been tested
|
|
for certain common S/MIME ciphers (\s-1RC2\s0, \s-1DES\s0, triple \s-1DES\s0) in \s-1CBC\s0 mode.
|
|
.SH "EXAMPLES"
|
|
.IX Header "EXAMPLES"
|
|
Get the number of rounds used in \s-1RC5:\s0
|
|
.PP
|
|
.Vb 2
|
|
\& int nrounds;
|
|
\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &i);
|
|
.Ve
|
|
Get the \s-1RC2\s0 effective key length:
|
|
.PP
|
|
.Vb 2
|
|
\& int key_bits;
|
|
\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC2_KEY_BITS, 0, &i);
|
|
.Ve
|
|
Set the number of rounds used in \s-1RC5:\s0
|
|
.PP
|
|
.Vb 2
|
|
\& int nrounds;
|
|
\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, i, NULL);
|
|
.Ve
|
|
Set the number of rounds used in \s-1RC2:\s0
|
|
.PP
|
|
.Vb 2
|
|
\& int nrounds;
|
|
\& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, i, NULL);
|
|
.Ve
|
|
.SH "SEE ALSO"
|
|
.IX Header "SEE ALSO"
|
|
openssl_evp(3)
|
|
.SH "HISTORY"
|
|
.IX Header "HISTORY"
|