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author | William Joye <wjoye@cfa.harvard.edu> | 2017-05-02 16:40:01 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2017-05-02 16:40:01 (GMT) |
commit | 0a2b8b8e0bc2e91a9f10659b30e2e4f5b79ce692 (patch) | |
tree | 3d0871d05cfd11f60b86829d2d93704034dad24e /openssl/doc/crypto/EVP_EncryptInit.pod | |
parent | e9abe0dba896d2b0fc22301588336e89ff246ba7 (diff) | |
download | blt-0a2b8b8e0bc2e91a9f10659b30e2e4f5b79ce692.zip blt-0a2b8b8e0bc2e91a9f10659b30e2e4f5b79ce692.tar.gz blt-0a2b8b8e0bc2e91a9f10659b30e2e4f5b79ce692.tar.bz2 |
reinstall
Diffstat (limited to 'openssl/doc/crypto/EVP_EncryptInit.pod')
-rw-r--r-- | openssl/doc/crypto/EVP_EncryptInit.pod | 594 |
1 files changed, 0 insertions, 594 deletions
diff --git a/openssl/doc/crypto/EVP_EncryptInit.pod b/openssl/doc/crypto/EVP_EncryptInit.pod deleted file mode 100644 index d951333..0000000 --- a/openssl/doc/crypto/EVP_EncryptInit.pod +++ /dev/null @@ -1,594 +0,0 @@ -=pod - -=head1 NAME - -EVP_CIPHER_CTX_init, EVP_EncryptInit_ex, EVP_EncryptUpdate, -EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptUpdate, -EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherUpdate, -EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length, -EVP_CIPHER_CTX_ctrl, EVP_CIPHER_CTX_cleanup, EVP_EncryptInit, -EVP_EncryptFinal, EVP_DecryptInit, EVP_DecryptFinal, -EVP_CipherInit, EVP_CipherFinal, EVP_get_cipherbyname, -EVP_get_cipherbynid, EVP_get_cipherbyobj, EVP_CIPHER_nid, -EVP_CIPHER_block_size, EVP_CIPHER_key_length, EVP_CIPHER_iv_length, -EVP_CIPHER_flags, EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher, -EVP_CIPHER_CTX_nid, EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length, -EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_get_app_data, -EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_flags, -EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1, EVP_CIPHER_asn1_to_param, -EVP_CIPHER_CTX_set_padding, EVP_enc_null, EVP_des_cbc, EVP_des_ecb, -EVP_des_cfb, EVP_des_ofb, EVP_des_ede_cbc, EVP_des_ede, EVP_des_ede_ofb, -EVP_des_ede_cfb, EVP_des_ede3_cbc, EVP_des_ede3, EVP_des_ede3_ofb, -EVP_des_ede3_cfb, EVP_desx_cbc, EVP_rc4, EVP_rc4_40, EVP_idea_cbc, -EVP_idea_ecb, EVP_idea_cfb, EVP_idea_ofb, EVP_idea_cbc, EVP_rc2_cbc, -EVP_rc2_ecb, EVP_rc2_cfb, EVP_rc2_ofb, EVP_rc2_40_cbc, EVP_rc2_64_cbc, -EVP_bf_cbc, EVP_bf_ecb, EVP_bf_cfb, EVP_bf_ofb, EVP_cast5_cbc, -EVP_cast5_ecb, EVP_cast5_cfb, EVP_cast5_ofb, EVP_rc5_32_12_16_cbc, -EVP_rc5_32_12_16_ecb, EVP_rc5_32_12_16_cfb, EVP_rc5_32_12_16_ofb, -EVP_aes_128_gcm, EVP_aes_192_gcm, EVP_aes_256_gcm, EVP_aes_128_ccm, -EVP_aes_192_ccm, EVP_aes_256_ccm - EVP cipher routines - -=head1 SYNOPSIS - - #include <openssl/evp.h> - - void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a); - - int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, - ENGINE *impl, unsigned char *key, unsigned char *iv); - int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, - int *outl, unsigned char *in, int inl); - int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, - int *outl); - - int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, - ENGINE *impl, unsigned char *key, unsigned char *iv); - int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, - int *outl, unsigned char *in, int inl); - int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, - int *outl); - - int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, - ENGINE *impl, unsigned char *key, unsigned char *iv, int enc); - int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, - int *outl, unsigned char *in, int inl); - int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, - int *outl); - - int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, - unsigned char *key, unsigned char *iv); - int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, - int *outl); - - int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, - unsigned char *key, unsigned char *iv); - int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, - int *outl); - - int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, - unsigned char *key, unsigned char *iv, int enc); - int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, - int *outl); - - int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding); - int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen); - int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr); - int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a); - - const EVP_CIPHER *EVP_get_cipherbyname(const char *name); - #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a)) - #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a)) - - #define EVP_CIPHER_nid(e) ((e)->nid) - #define EVP_CIPHER_block_size(e) ((e)->block_size) - #define EVP_CIPHER_key_length(e) ((e)->key_len) - #define EVP_CIPHER_iv_length(e) ((e)->iv_len) - #define EVP_CIPHER_flags(e) ((e)->flags) - #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE) - int EVP_CIPHER_type(const EVP_CIPHER *ctx); - - #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher) - #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid) - #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size) - #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len) - #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len) - #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data) - #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d)) - #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c)) - #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags) - #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE) - - int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type); - int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type); - -=head1 DESCRIPTION - -The EVP cipher routines are a high level interface to certain -symmetric ciphers. - -EVP_CIPHER_CTX_init() initializes cipher contex B<ctx>. - -EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption -with cipher B<type> from ENGINE B<impl>. B<ctx> must be initialized -before calling this function. B<type> is normally supplied -by a function such as EVP_aes_256_cbc(). If B<impl> is NULL then the -default implementation is used. B<key> is the symmetric key to use -and B<iv> is the IV to use (if necessary), the actual number of bytes -used for the key and IV depends on the cipher. It is possible to set -all parameters to NULL except B<type> in an initial call and supply -the remaining parameters in subsequent calls, all of which have B<type> -set to NULL. This is done when the default cipher parameters are not -appropriate. - -EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and -writes the encrypted version to B<out>. This function can be called -multiple times to encrypt successive blocks of data. The amount -of data written depends on the block alignment of the encrypted data: -as a result the amount of data written may be anything from zero bytes -to (inl + cipher_block_size - 1) so B<out> should contain sufficient -room. The actual number of bytes written is placed in B<outl>. - -If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts -the "final" data, that is any data that remains in a partial block. -It uses L<standard block padding|/NOTES> (aka PKCS padding). The encrypted -final data is written to B<out> which should have sufficient space for -one cipher block. The number of bytes written is placed in B<outl>. After -this function is called the encryption operation is finished and no further -calls to EVP_EncryptUpdate() should be made. - -If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more -data and it will return an error if any data remains in a partial block: -that is if the total data length is not a multiple of the block size. - -EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the -corresponding decryption operations. EVP_DecryptFinal() will return an -error code if padding is enabled and the final block is not correctly -formatted. The parameters and restrictions are identical to the encryption -operations except that if padding is enabled the decrypted data buffer B<out> -passed to EVP_DecryptUpdate() should have sufficient room for -(B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in -which case B<inl> bytes is sufficient. - -EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are -functions that can be used for decryption or encryption. The operation -performed depends on the value of the B<enc> parameter. It should be set -to 1 for encryption, 0 for decryption and -1 to leave the value unchanged -(the actual value of 'enc' being supplied in a previous call). - -EVP_CIPHER_CTX_cleanup() clears all information from a cipher context -and free up any allocated memory associate with it. It should be called -after all operations using a cipher are complete so sensitive information -does not remain in memory. - -EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a -similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex and -EVP_CipherInit_ex() except the B<ctx> parameter does not need to be -initialized and they always use the default cipher implementation. - -EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are -identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and -EVP_CipherFinal_ex(). In previous releases they also cleaned up -the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean() -must be called to free any context resources. - -EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() -return an EVP_CIPHER structure when passed a cipher name, a NID or an -ASN1_OBJECT structure. - -EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when -passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID -value is an internal value which may not have a corresponding OBJECT -IDENTIFIER. - -EVP_CIPHER_CTX_set_padding() enables or disables padding. By default -encryption operations are padded using standard block padding and the -padding is checked and removed when decrypting. If the B<pad> parameter -is zero then no padding is performed, the total amount of data encrypted -or decrypted must then be a multiple of the block size or an error will -occur. - -EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key -length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> -structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length -for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a -given cipher, the value of EVP_CIPHER_CTX_key_length() may be different -for variable key length ciphers. - -EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx. -If the cipher is a fixed length cipher then attempting to set the key -length to any value other than the fixed value is an error. - -EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV -length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>. -It will return zero if the cipher does not use an IV. The constant -B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers. - -EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block -size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> -structure. The constant B<EVP_MAX_IV_LENGTH> is also the maximum block -length for all ciphers. - -EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed -cipher or context. This "type" is the actual NID of the cipher OBJECT -IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and -128 bit RC2 have the same NID. If the cipher does not have an object -identifier or does not have ASN1 support this function will return -B<NID_undef>. - -EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed -an B<EVP_CIPHER_CTX> structure. - -EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode: -EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE or -EVP_CIPH_OFB_MODE. If the cipher is a stream cipher then -EVP_CIPH_STREAM_CIPHER is returned. - -EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based -on the passed cipher. This will typically include any parameters and an -IV. The cipher IV (if any) must be set when this call is made. This call -should be made before the cipher is actually "used" (before any -EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function -may fail if the cipher does not have any ASN1 support. - -EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1 -AlgorithmIdentifier "parameter". The precise effect depends on the cipher -In the case of RC2, for example, it will set the IV and effective key length. -This function should be called after the base cipher type is set but before -the key is set. For example EVP_CipherInit() will be called with the IV and -key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally -EVP_CipherInit() again with all parameters except the key set to NULL. It is -possible for this function to fail if the cipher does not have any ASN1 support -or the parameters cannot be set (for example the RC2 effective key length -is not supported. - -EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined -and set. - -=head1 RETURN VALUES - -EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex() -return 1 for success and 0 for failure. - -EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure. -EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success. - -EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure. -EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success. - -EVP_CIPHER_CTX_cleanup() returns 1 for success and 0 for failure. - -EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() -return an B<EVP_CIPHER> structure or NULL on error. - -EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID. - -EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block -size. - -EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key -length. - -EVP_CIPHER_CTX_set_padding() always returns 1. - -EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV -length or zero if the cipher does not use an IV. - -EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's -OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER. - -EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure. - -EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for -success or zero for failure. - -=head1 CIPHER LISTING - -All algorithms have a fixed key length unless otherwise stated. - -=over 4 - -=item EVP_enc_null() - -Null cipher: does nothing. - -=item EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void) - -DES in CBC, ECB, CFB and OFB modes respectively. - -=item EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void), EVP_des_ede_cfb(void) - -Two key triple DES in CBC, ECB, CFB and OFB modes respectively. - -=item EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void) - -Three key triple DES in CBC, ECB, CFB and OFB modes respectively. - -=item EVP_desx_cbc(void) - -DESX algorithm in CBC mode. - -=item EVP_rc4(void) - -RC4 stream cipher. This is a variable key length cipher with default key length 128 bits. - -=item EVP_rc4_40(void) - -RC4 stream cipher with 40 bit key length. This is obsolete and new code should use EVP_rc4() -and the EVP_CIPHER_CTX_set_key_length() function. - -=item EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void) - -IDEA encryption algorithm in CBC, ECB, CFB and OFB modes respectively. - -=item EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void) - -RC2 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key -length cipher with an additional parameter called "effective key bits" or "effective key length". -By default both are set to 128 bits. - -=item EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void) - -RC2 algorithm in CBC mode with a default key length and effective key length of 40 and 64 bits. -These are obsolete and new code should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and -EVP_CIPHER_CTX_ctrl() to set the key length and effective key length. - -=item EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void); - -Blowfish encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key -length cipher. - -=item EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void) - -CAST encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key -length cipher. - -=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) - -RC5 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key length -cipher with an additional "number of rounds" parameter. By default the key length is set to 128 -bits and 12 rounds. - -=item EVP_aes_128_gcm(void), EVP_aes_192_gcm(void), EVP_aes_256_gcm(void) - -AES Galois Counter Mode (GCM) for 128, 192 and 256 bit keys respectively. -These ciphers require additional control operations to function correctly: see -L<GCM mode> section below for details. - -=item EVP_aes_128_ccm(void), EVP_aes_192_ccm(void), EVP_aes_256_ccm(void) - -AES Counter with CBC-MAC Mode (CCM) for 128, 192 and 256 bit keys respectively. -These ciphers require additional control operations to function correctly: see -CCM mode section below for details. - -=back - -=head1 GCM Mode - -For GCM mode ciphers the behaviour of the EVP interface is subtly altered and -several GCM specific ctrl operations are supported. - -To specify any additional authenticated data (AAD) a call to EVP_CipherUpdate(), -EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output -parameter B<out> set to B<NULL>. - -When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal() -indicates if the operation was successful. If it does not indicate success -the authentication operation has failed and any output data B<MUST NOT> -be used as it is corrupted. - -The following ctrls are supported in GCM mode: - - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, ivlen, NULL); - -Sets the GCM IV length: this call can only be made before specifying an IV. If -not called a default IV length is used (96 bits for AES). - - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, taglen, tag); - -Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>. -This call can only be made when encrypting data and B<after> all data has been -processed (e.g. after an EVP_EncryptFinal() call). - - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, taglen, tag); - -Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal -when decrypting data and must be made B<before> any data is processed (e.g. -before any EVP_DecryptUpdate() call). - -See L<EXAMPLES> below for an example of the use of GCM mode. - -=head1 CCM Mode - -The behaviour of CCM mode ciphers is similar to CCM mode but with a few -additional requirements and different ctrl values. - -Like GCM mode any additional authenticated data (AAD) is passed by calling -EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output -parameter B<out> set to B<NULL>. Additionally the total plaintext or ciphertext -length B<MUST> be passed to EVP_CipherUpdate(), EVP_EncryptUpdate() or -EVP_DecryptUpdate() with the output and input parameters (B<in> and B<out>) -set to B<NULL> and the length passed in the B<inl> parameter. - -The following ctrls are supported in CCM mode: - - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_TAG, taglen, tag); - -This call is made to set the expected B<CCM> tag value when decrypting or -the length of the tag (with the B<tag> parameter set to NULL) when encrypting. -The tag length is often referred to as B<M>. If not set a default value is -used (12 for AES). - - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL); - -Sets the CCM B<L> value. If not set a default is used (8 for AES). - - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_IVLEN, ivlen, NULL); - -Sets the CCM nonce (IV) length: this call can only be made before specifying -an nonce value. The nonce length is given by B<15 - L> so it is 7 by default -for AES. - - - -=head1 NOTES - -Where possible the B<EVP> 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. Additionally, the -B<EVP> interface will ensure the use of platform specific cryptographic -acceleration such as AES-NI (the low level interfaces do not provide the -guarantee). - -PKCS padding works by adding B<n> padding bytes of value B<n> 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 B<n> 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. - -When decrypting the final block is checked to see if it has the correct form. - -Although the decryption operation can produce an error if padding is enabled, -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. - -If padding is disabled then the decryption operation will always succeed if -the total amount of data decrypted is a multiple of the block size. - -The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(), -EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for -compatibility with existing code. New code should use EVP_EncryptInit_ex(), -EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(), -EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an -existing context without allocating and freeing it up on each call. - -=head1 BUGS - -For RC5 the number of rounds can currently only be set to 8, 12 or 16. This is -a limitation of the current RC5 code rather than the EVP interface. - -EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH 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 EVP_MAX_KEY_LENGTH bytes. - -The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested -for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode. - -=head1 EXAMPLES - -Encrypt a string using IDEA: - - int do_crypt(char *outfile) - { - unsigned char outbuf[1024]; - int outlen, tmplen; - /* Bogus key and IV: we'd normally set these from - * another source. - */ - unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}; - unsigned char iv[] = {1,2,3,4,5,6,7,8}; - char intext[] = "Some Crypto Text"; - EVP_CIPHER_CTX ctx; - FILE *out; - - EVP_CIPHER_CTX_init(&ctx); - EVP_EncryptInit_ex(&ctx, EVP_idea_cbc(), NULL, key, iv); - - if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext))) - { - /* Error */ - return 0; - } - /* Buffer passed to EVP_EncryptFinal() must be after data just - * encrypted to avoid overwriting it. - */ - if(!EVP_EncryptFinal_ex(&ctx, outbuf + outlen, &tmplen)) - { - /* Error */ - return 0; - } - outlen += tmplen; - EVP_CIPHER_CTX_cleanup(&ctx); - /* Need binary mode for fopen because encrypted data is - * binary data. Also cannot use strlen() on it because - * it wont be null terminated and may contain embedded - * nulls. - */ - out = fopen(outfile, "wb"); - fwrite(outbuf, 1, outlen, out); - fclose(out); - return 1; - } - -The ciphertext from the above example can be decrypted using the B<openssl> -utility with the command line (shown on two lines for clarity): - - openssl idea -d <filename - -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 - -General encryption and decryption function example using FILE I/O and AES128 -with a 128-bit key: - - int do_crypt(FILE *in, FILE *out, int do_encrypt) - { - /* Allow enough space in output buffer for additional block */ - unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH]; - int inlen, outlen; - EVP_CIPHER_CTX ctx; - /* Bogus key and IV: we'd normally set these from - * another source. - */ - unsigned char key[] = "0123456789abcdeF"; - unsigned char iv[] = "1234567887654321"; - - /* Don't set key or IV right away; we want to check lengths */ - EVP_CIPHER_CTX_init(&ctx); - EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL, - do_encrypt); - OPENSSL_assert(EVP_CIPHER_CTX_key_length(&ctx) == 16); - OPENSSL_assert(EVP_CIPHER_CTX_iv_length(&ctx) == 16); - - /* Now we can set key and IV */ - EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt); - - for(;;) - { - inlen = fread(inbuf, 1, 1024, in); - if(inlen <= 0) break; - if(!EVP_CipherUpdate(&ctx, outbuf, &outlen, inbuf, inlen)) - { - /* Error */ - EVP_CIPHER_CTX_cleanup(&ctx); - return 0; - } - fwrite(outbuf, 1, outlen, out); - } - if(!EVP_CipherFinal_ex(&ctx, outbuf, &outlen)) - { - /* Error */ - EVP_CIPHER_CTX_cleanup(&ctx); - return 0; - } - fwrite(outbuf, 1, outlen, out); - - EVP_CIPHER_CTX_cleanup(&ctx); - return 1; - } - - -=head1 SEE ALSO - -L<evp(3)|evp(3)> - -=head1 HISTORY - -EVP_CIPHER_CTX_init(), EVP_EncryptInit_ex(), EVP_EncryptFinal_ex(), -EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(), EVP_CipherInit_ex(), -EVP_CipherFinal_ex() and EVP_CIPHER_CTX_set_padding() appeared in -OpenSSL 0.9.7. - -IDEA appeared in OpenSSL 0.9.7 but was often disabled due to -patent concerns; the last patents expired in 2012. - -=cut |